<SEC-DOCUMENT>0001144204-18-006967.txt : 20180209
<SEC-HEADER>0001144204-18-006967.hdr.sgml : 20180209
<ACCEPTANCE-DATETIME>20180209163014
ACCESSION NUMBER:		0001144204-18-006967
CONFORMED SUBMISSION TYPE:	SC 13D
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20180209
DATE AS OF CHANGE:		20180209
GROUP MEMBERS:		PETER KOLCHINSKY

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Solid Biosciences Inc.
		CENTRAL INDEX KEY:			0001707502
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		IRS NUMBER:				900943402

	FILING VALUES:
		FORM TYPE:		SC 13D
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-90280
		FILM NUMBER:		18592187

	BUSINESS ADDRESS:	
		STREET 1:		161 FIRST STREET, THIRD FLOOR
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142
		BUSINESS PHONE:		617-337-4682

	MAIL ADDRESS:	
		STREET 1:		161 FIRST STREET, THIRD FLOOR
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Solid Biosciences, LLC
		DATE OF NAME CHANGE:	20170524

FILED BY:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			RA CAPITAL MANAGEMENT, LLC
		CENTRAL INDEX KEY:			0001346824
		IRS NUMBER:				830406777
		STATE OF INCORPORATION:			MA
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13D

	BUSINESS ADDRESS:	
		STREET 1:		20 PARK PLAZA, SUITE 1200
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
		BUSINESS PHONE:		617-778-2500

	MAIL ADDRESS:	
		STREET 1:		20 PARK PLAZA, SUITE 1200
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
</SEC-HEADER>
<DOCUMENT>
<TYPE>SC 13D
<SEQUENCE>1
<FILENAME>tv485500_sc13d.htm
<DESCRIPTION>SC 13D
<TEXT>
<HTML>
<HEAD>
     <TITLE></TITLE>
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<P STYLE="margin: 0">&nbsp;</P>

<P STYLE="margin: 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR>
    <TD ROWSPAN="3" STYLE="vertical-align: top; width: 21%; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: justify">&nbsp;</TD>
    <TD ROWSPAN="3" STYLE="vertical-align: top; width: 53%; border-right: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">UNITED STATES</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SECURITIES AND EXCHANGE COMMISSION</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Washington, D.C. 20549</B></P></TD>
    <TD STYLE="vertical-align: top; width: 25%; border-top: Black 1pt solid; border-right: Black 1pt solid; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt">OMB APPROVAL</FONT></TD>
    <TD STYLE="width: 1%">&nbsp;</TD></TR>
<TR>
    <TD ROWSPAN="2" STYLE="vertical-align: top; border-right: Black 1pt solid; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">OMB Number:&#9;3235-0145</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Expires: &#9;February 28, 2009</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Estimated average burden</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">hours per response&hellip;&#9;10.4</P></TD>
    <TD>&nbsp;</TD></TR>
<TR>
    <TD>&nbsp;</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SCHEDULE 13D</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Under the Securities Exchange Act of
1934</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>(Amendment No. ___)*</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; border-bottom: Black 1pt solid">Solid
Biosciences Inc.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Name of Issuer)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; text-indent: 0.25in; border-bottom: Black 1pt solid">Common Stock, par
value $0.001 per share</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Title of Class of Securities)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center;  border-bottom: Black 1pt solid">83422E105</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(CUSIP Number)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">RA Capital Management, LLC</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">20 Park Plaza, Suite 1200</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Boston, MA 02116</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Telephone: 617.778.2512</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; border-bottom: Black 1pt solid">Attn: Peter Kolchinsky</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Name, Address and Telephone Number of Person
Authorized to<BR>
Receive Notices and Communications)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center; border-bottom: Black 1pt solid">January 30, 2018</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Date of Event Which Requires Filing of
this Statement)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 9.35pt 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 9.35pt 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">If the filing person has previously filed a statement on Schedule&nbsp;13G
to report the acquisition that is the subject of this Schedule&nbsp;13D, and is filing this schedule because of &sect;&sect;240.13d-1(e),
240.13d-1(f) or 240.13d-1(g), check the following box. [ ]</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Note: </B>Schedules filed in paper format shall include a
signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for other parties to whom copies are to
be sent.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">* The remainder of this cover page shall be filled out for a
reporting person&rsquo;s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment
containing information which would alter disclosures provided in a prior cover page.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">The information required on the remainder of this cover page
shall not be deemed to be &ldquo;filed&rdquo; for the purpose of Section 18 of the Securities Exchange Act of 1934 (&ldquo;Act&rdquo;)
or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however,
see the Notes).</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>


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    <DIV STYLE="margin-top: 12pt; margin-bottom: 6pt; border-bottom: Black 1pt solid"><P STYLE="margin: 0pt">&nbsp;</P></DIV>
    <DIV STYLE="page-break-before: always; margin-top: 6pt; margin-bottom: 12pt"><P STYLE="margin: 0pt"></P><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">CUSIP No. 83422E105</P><P STYLE="margin: 0pt"></P></DIV>
    <!-- Field: /Page -->

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="border-top: Black 1pt solid; border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">1</TD>
    <TD COLSPAN="3" STYLE="border-top: Black 1pt solid; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Names of Reporting Persons.</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left"><B>RA Capital Management, LLC</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">2</TD>
    <TD COLSPAN="3" STYLE="padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: justify">Check the Appropriate Box if a Member of a Group (See Instructions)</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">&nbsp;</TD>
    <TD COLSPAN="3" STYLE="padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: justify">(a)&#9;[ ]</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">&nbsp;</TD>
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: justify">(b)&#9;[ ] </TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">3</TD>
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: justify">SEC Use Only</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">4</TD>
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Source of Funds (See Instructions):</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">AF</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">5</TD>
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Check if disclosure of legal proceedings
        is required pursuant to Items 2(d) or 2(e):</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">[ ]</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">6</TD>
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Citizenship or Place of Organization. <B>Massachusetts</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><B>&nbsp;</B></P></TD></TR>
<TR>
    <TD COLSPAN="2" ROWSPAN="4" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Number</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">of Shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Beneficially</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Owned by</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Each</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Reporting</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Person With</P></TD>
    <TD COLSPAN="2" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">7&nbsp;&nbsp;&nbsp;Sole Voting Power <B>0 shares</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 15pt; text-align: justify; text-indent: 0.5in">&nbsp;</P></TD></TR>
<TR>
    <TD COLSPAN="2" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">8&nbsp;&nbsp;&nbsp;Shared Voting Power <B>2,689,444 shares</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 15pt; text-align: justify; text-indent: 0.5in">&nbsp;</P></TD></TR>
<TR>
    <TD COLSPAN="2" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">9&nbsp;&nbsp;&nbsp;Sole Dispositive Power <B>0 shares</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 15pt; text-align: justify; text-indent: 0.5in">&nbsp;</P></TD></TR>
<TR>
    <TD COLSPAN="2" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">10&nbsp;&nbsp;Shared
        Dispositive Power <B>2,689,444 shares</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 15pt; text-align: justify; text-indent: 0.5in">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">11</TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Aggregate Amount Beneficially Owned by
        Each Reporting Person</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.05in; text-align: justify"><B>2,689,444 shares</B></P></TD>
    <TD STYLE="font-size: 10pt; text-align: justify">&nbsp;</TD></TR>
<TR>
    <TD STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">12</TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: justify">Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[ ] </TD>
    <TD STYLE="font-size: 10pt; text-align: justify">&nbsp;</TD></TR>
<TR>
    <TD STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">13</TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Percent of Class Represented by Amount
        in Row (11)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><B>7.9%<FONT STYLE="font-size: 10pt"><U><SUP>1</SUP></U></FONT></B></P></TD>
    <TD STYLE="font-size: 10pt; text-align: justify">&nbsp;</TD></TR>
<TR>
    <TD STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">14</TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Type of Reporting Person (See Instructions)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><B>IA, OO (Limited Liability Company)</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 15pt; text-align: justify">&nbsp;</P></TD>
    <TD STYLE="font-size: 10pt; text-align: justify">&nbsp;</TD></TR>
<TR>
    <TD STYLE="width: 6%">&nbsp;</TD>
    <TD STYLE="width: 10%">&nbsp;</TD>
    <TD STYLE="width: 83%">&nbsp;</TD>
    <TD STYLE="width: 1%">&nbsp;</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><U><SUP>1</SUP></U> The reporting person is the beneficial
owner of 2,689,444 shares of the Issuer&rsquo;s Common Stock which constitute approximately 7.87% of the class outstanding. The
percentage calculation assumes that there are currently 34,151,022 outstanding shares of Common Stock of the Issuer, based upon
the closing of the Issuer&rsquo;s initial public offering, as reported in the Issuer&rsquo;s prospectus filed with the Securities
and Exchange Commission (&ldquo;SEC&rdquo;) on January 29, 2018.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>


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    <DIV STYLE="page-break-before: always; margin-top: 6pt; margin-bottom: 12pt"><P STYLE="margin: 0pt"></P><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">CUSIP No. 83422E105</P><P STYLE="margin: 0pt"></P></DIV>
    <!-- Field: /Page -->

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="border-top: Black 1pt solid; border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">1</TD>
    <TD COLSPAN="3" STYLE="border-top: Black 1pt solid; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Names of Reporting Persons.</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><B>&nbsp;</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><B>Peter Kolchinsky</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">2</TD>
    <TD COLSPAN="3" STYLE="padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: justify">Check the Appropriate Box if a Member of a Group (See Instructions)</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">&nbsp;</TD>
    <TD COLSPAN="3" STYLE="padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: justify">(a)&#9;[ ]</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">&nbsp;</TD>
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: justify">(b)&#9;[ ]</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">3</TD>
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: justify">SEC Use Only</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">4</TD>
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Source of Funds (See Instructions):</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">AF</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">5</TD>
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Check if disclosure of legal proceedings
        is required pursuant to Items 2(d) or 2(e):</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">[ ]</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">6</TD>
    <TD COLSPAN="3" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Citizenship or Place of Organization. <B>United
        States</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><B>&nbsp;</B></P></TD></TR>
<TR>
    <TD COLSPAN="2" ROWSPAN="4" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Number</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">of Shares</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Beneficially</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Owned by</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Each</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Reporting</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Person With</P></TD>
    <TD COLSPAN="2" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">7&nbsp;&nbsp;&nbsp;Sole Voting Power <B>0 shares</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 15pt; text-align: justify; text-indent: 0.5in">&nbsp;</P></TD></TR>
<TR>
    <TD COLSPAN="2" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">8&nbsp;&nbsp;&nbsp;Shared Voting Power <B>2,689,444 shares</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 15pt; text-align: justify; text-indent: 0.5in">&nbsp;</P></TD></TR>
<TR>
    <TD COLSPAN="2" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">9&nbsp;&nbsp;&nbsp;Sole Dispositive Power <B>0 shares</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 15pt; text-align: justify; text-indent: 0.5in">&nbsp;</P></TD></TR>
<TR>
    <TD COLSPAN="2" STYLE="border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">10&nbsp;&nbsp;Shared
        Dispositive Power <B>2,689,444 shares</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 15pt; text-align: justify; text-indent: 0.5in">&nbsp;</P></TD></TR>
<TR>
    <TD STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">11</TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Aggregate Amount Beneficially Owned by
        Each Reporting Person</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.05in; text-align: justify"><B>2,689,444 shares</B></P></TD>
    <TD STYLE="font-size: 10pt; text-align: justify">&nbsp;</TD></TR>
<TR>
    <TD STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">12</TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: justify">Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[ ] </TD>
    <TD STYLE="font-size: 10pt; text-align: justify">&nbsp;</TD></TR>
<TR>
    <TD STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">13</TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Percent of Class Represented by Amount
        in Row (11)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><B>7.9%<FONT STYLE="font-size: 10pt"><U><SUP>2</SUP></U></FONT></B></P></TD>
    <TD STYLE="font-size: 10pt; text-align: justify">&nbsp;</TD></TR>
<TR>
    <TD STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-top: 3pt; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">14</TD>
    <TD COLSPAN="2" STYLE="vertical-align: top; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Type of Reporting Person (See Instructions)</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><B>HC, IN</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 15pt; text-align: justify">&nbsp;</P></TD>
    <TD STYLE="font-size: 10pt; text-align: justify">&nbsp;</TD></TR>
<TR>
    <TD STYLE="width: 6%">&nbsp;</TD>
    <TD STYLE="width: 10%">&nbsp;</TD>
    <TD STYLE="width: 83%">&nbsp;</TD>
    <TD STYLE="width: 1%">&nbsp;</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><U><SUP>2</SUP></U> The reporting person is the beneficial
owner of 2,689,444 shares of the Issuer&rsquo;s Common Stock which constitute approximately 7.87% of the class outstanding. The
percentage calculation assumes that there are currently 34,151,022 outstanding shares of Common Stock of the Issuer, based upon
the closing of the Issuer&rsquo;s initial public offering, as reported in the Issuer&rsquo;s prospectus filed with the SEC on
January 29, 2018.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>


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    <DIV STYLE="page-break-before: always; margin-top: 6pt; margin-bottom: 12pt"><P STYLE="margin: 0pt"></P><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">CUSIP No. 83422E105</P><P STYLE="margin: 0pt"></P></DIV>
    <!-- Field: /Page -->

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><B><U>SCHEDULE 13D</U></B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" WIDTH="100%" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0"></TD><TD STYLE="width: 1in"><B>Item 1.</B></TD><TD STYLE="text-align: justify"><B>Security and Issuer</B></TD></TR></TABLE>

<P STYLE="margin-top: 0pt; margin-bottom: 0pt; font: 10pt Times New Roman, Times, Serif">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">This Schedule&nbsp;13D relates to common
stock, par value $0.001 per share (the &ldquo;Common Stock&rdquo;), of Solid Biosciences Inc., a Delaware corporation (the &ldquo;Issuer&rdquo;).&nbsp;&nbsp;The
address of the principal executive offices of the Issuer is: 161 First Street, Third Floor, Cambridge, MA 02142.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" WIDTH="100%" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0"></TD><TD STYLE="width: 1in"><B>Item 2.</B></TD><TD STYLE="text-align: justify"><B>Identity and Background</B></TD></TR></TABLE>

<P STYLE="margin-top: 0pt; margin-bottom: 0pt; font: 10pt Times New Roman, Times, Serif">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">(a)&nbsp;This Schedule&nbsp;13D is being
filed on behalf of (i)&nbsp;RA Capital Management, LLC (&ldquo;RA Capital&rdquo;) and (ii)&nbsp;Peter Kolchinsky and together with
each of the foregoing, the &ldquo;Reporting Persons&rdquo;).</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Common Stock reported herein for RA Capital
represent shares reported for RA Capital Healthcare Fund, L.P. (the &ldquo;Fund&rdquo;) as well as shares held in a separately
managed account (the &ldquo;Account&rdquo;). RA Capital is the general partner of the Fund and serves as investment adviser for
the Account. Peter Kolchinsky is the manager of RA Capital. As the investment adviser to the Fund and the Account, RA Capital may
be deemed a beneficial owner, for purposes of Section 13(d) of the Securities Exchange Act of 1934 (the &ldquo;Act&rdquo;), of
any securities of the Issuer owned by the Fund or the Account. As the manager of RA Capital, Mr. Kolchinsky may be deemed a beneficial
owner, for purposes of Section 13(d) of the Act, of any securities of the Issuer beneficially owned by RA Capital. RA Capital is
a registered investment adviser within the meaning of Rule 13d-1(b)(1)(ii)(E) and Rule 16a-1(a)(v), and Mr. Kolchinsky is a parent
or control person of RA Capital within the meaning of Rule 13d-1(b)(1)(ii)(G) and Rule 16a-1(a)(1)(vii). RA Capital and Mr. Kolchinsky
disclaim beneficial ownership of the securities reported in this Schedule 13D Statement (the &ldquo;Statement&rdquo;) other than
for the purpose of determining their obligations under Section 13(d) of the Act, and neither the filing of the Statement nor the
filing of this Amendment shall be deemed an admission that either RA Capital or Mr. Kolchinsky is the beneficial owner of such
securities for any other purpose.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">(b)&nbsp;The business address of each of
the Reporting Persons is: 20 Park Plaza, Suite 1200, Boston, MA 02116.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">(c)&nbsp;The Fund is a private investment
vehicle. RA Capital provides investment management services to the Fund and the Account. The principal occupation of Mr. Kolchinsky
is investment management.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">(d)&nbsp;None of the Reporting Persons
has, during the last five years, been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">(e)&nbsp;None of the Reporting Persons
has, during the last five years, been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction
and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting
or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">(f)&nbsp;See Item 6 of the cover pages.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" WIDTH="100%" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0"></TD><TD STYLE="width: 1in"><B>Item 3.</B></TD><TD STYLE="text-align: justify"><B>Source and Amount of Funds or Other Consideration</B></TD></TR></TABLE>

<P STYLE="margin-top: 0pt; margin-bottom: 0pt; font: 10pt Times New Roman, Times, Serif">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Prior to the Issuer&rsquo;s initial public
offering (the &ldquo;IPO&rdquo;), the Reporting Persons acquired <FONT STYLE="font-size: 10pt">equity interests in </FONT>the Issuer&rsquo;s
predecessor in a private placement, and those interests converted into 1,689,444 shares of Common Stock prior to consummation of
the IPO. The Reporting Persons purchased 1,000,000 shares of Common Stock from the underwriters of the IPO. All purchases were
for cash and were funded by working capital of the Fund and the Account.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>


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    <DIV STYLE="page-break-before: always; margin-top: 6pt; margin-bottom: 12pt"><P STYLE="margin: 0pt"></P><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">CUSIP No. 83422E105</P><P STYLE="margin: 0pt"></P></DIV>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" WIDTH="100%" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0"></TD><TD STYLE="width: 1in"><B>Item 4.</B></TD><TD STYLE="text-align: justify"><B>Purpose of Transaction</B></TD></TR></TABLE>

<P STYLE="margin-top: 0pt; margin-bottom: 0pt; font: 10pt Times New Roman, Times, Serif">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">The Reporting Persons acquired the Common
Stock reported herein for investment purposes and not with an intent, purpose or effect of changing control of the Issuer. Although
the Reporting Persons currently have no plan or proposal to acquire any additional Common Stock or to dispose of any of the Common
Stock reported herein, the Reporting Persons may acquire additional Common Stock from time to time or dispose of Common Stock they
beneficially own, consistent with their investment purposes and in amounts to be determined by the Reporting Persons based upon
a number of factors, including, without limitation, their ongoing assessment of the Issuer's business prospects, prevailing market
conditions, the availability of other investment opportunities, and/or other considerations.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">In addition, consistent with their investment
purpose, the Reporting Persons may engage in communications with persons associated with the Issuer, including shareholders of
the Issuer, officers of the Issuer and/or members of the board of directors of the Issuer, to discuss matters regarding the Issuer,
including but not limited to its operations and strategic direction. Mr. Rajeev Shah, a portfolio manager and managing director
of RA Capital, currently serves as a director of the Issuer and therefore will engage in regular discussions with the Issuer&rsquo;s
board of directors and management as part of his duties as a director.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">The Reporting Persons have no plans or
proposals that relate to, or could result in, any of the matters referred to in paragraphs (a) through (j), inclusive, of the instructions
to Item 4 of Schedule 13D.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">The Reporting Persons may, however, change
their purpose and formulate and implement plans or proposals with respect to the Issuer at any time and from time to time. Any
such action may be made by the Reporting Persons alone or in conjunction with other shareholders, potential acquirers, financing
sources and/or other third parties and could include one or more purposes, plans or proposals that relate to or would result in
actions required to be reported herein in accordance with Item 4 of Schedule 13D.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" WIDTH="100%" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0"></TD><TD STYLE="width: 1in"><B>Item 5.</B></TD><TD STYLE="text-align: justify"><B>Interest in Securities of the Issuer</B></TD></TR></TABLE>

<P STYLE="margin-top: 0pt; margin-bottom: 0pt; font: 10pt Times New Roman, Times, Serif">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">(a) and (b) See Items 7-11 of the cover
pages and Item 2 above.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">(c) The following table lists the Reporting
Persons&rsquo; transactions in Common Stock that were effected during the sixty day period prior to the filing of this Schedule
13D:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font: 10pt Times New Roman, Times, Serif; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 24%; border: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: center"><B>Transaction</B></TD>
    <TD STYLE="width: 24%; border-top: Black 1pt solid; border-right: Black 1pt solid; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: center"><B>Date</B></TD>
    <TD STYLE="width: 33%; border-top: Black 1pt solid; border-right: Black 1pt solid; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: center"><B>No. Shares</B></TD>
    <TD STYLE="width: 19%; border-top: Black 1pt solid; border-right: Black 1pt solid; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: center"><B>Price</B></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-right: Black 1pt solid; border-bottom: Black 1pt solid; border-left: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: left">Conversion</TD>
    <TD STYLE="border-right: Black 1pt solid; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">30-Jan-2018</TD>
    <TD STYLE="border-right: Black 1pt solid; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">1,368,981* and 320,463</TD>
    <TD STYLE="border-right: Black 1pt solid; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">(1) </TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-right: Black 1pt solid; border-bottom: Black 1pt solid; border-left: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: left">Purchase</TD>
    <TD STYLE="border-right: Black 1pt solid; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">30-Jan-2018</TD>
    <TD STYLE="border-right: Black 1pt solid; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">808,990* and 191,010 </TD>
    <TD STYLE="border-right: Black 1pt solid; border-bottom: Black 1pt solid; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; text-align: right">$16.00 </TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>


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    <DIV STYLE="page-break-before: always; margin-top: 6pt; margin-bottom: 12pt"><P STYLE="margin: 0pt"></P><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">CUSIP No. 83422E105</P><P STYLE="margin: 0pt"></P></DIV>
    <!-- Field: /Page -->

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">(1) The Reporting Persons acquired Series
1 Senior Preferred Units, Series C Common Units, and Series 2 Senior Preferred Units of the Issuer&rsquo;s predecessor more than
60 days prior to the IPO. All units converted automatically on a 1-for-.8485 basis into Common Stock prior to the IPO.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Shares marked with an * were acquired by
the Fund. The remaining shares were acquired for the Account.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">(d) Not applicable.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">(e) Not applicable.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" WIDTH="100%" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0"></TD><TD STYLE="width: 1in"><B>Item 6.</B></TD><TD STYLE="text-align: justify"><B>Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer</B></TD></TR></TABLE>

<P STYLE="margin-top: 0pt; margin-bottom: 0pt; font: 10pt Times New Roman, Times, Serif">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">The Reporting Persons have entered into
a standard lock-up agreement with the Issuer and the underwriters of the IPO, prohibiting any sale of the Common Stock reported
herein during the 180 days following the closing of the offering. The Reporting Persons may be released from lock-up prior to the
expiration of the lock-up period at the sole discretion of the underwriters.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" WIDTH="100%" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0"></TD><TD STYLE="width: 1in"><B>Item 7.</B></TD><TD STYLE="text-align: justify"><B>Material to Be Filed as Exhibits</B></TD></TR></TABLE>

<P STYLE="margin-top: 0pt; margin-bottom: 0pt; font: 10pt Times New Roman, Times, Serif">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Exhibit 1&#9;Joint Filing Agreement by
and among the Reporting Persons.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>


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    <DIV STYLE="page-break-before: always; margin-top: 6pt; margin-bottom: 12pt"><P STYLE="margin: 0pt"></P><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">CUSIP No. 83422E105</P><P STYLE="margin: 0pt"></P></DIV>
    <!-- Field: /Page -->

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SIGNATURE</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 45pt">After reasonable inquiry
and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 45pt">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Date:&#9;February 9, 2018</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">RA CAPITAL MANAGEMENT, LLC</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">By: /s/ Peter Kolchinsky</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">-------------------------------------------------</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">Peter Kolchinsky</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">Manager</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">PETER KOLCHINSKY</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">/s/ Peter Kolchinsky</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">-------------------------------------------------</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>


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    <DIV STYLE="page-break-before: always; margin-top: 6pt; margin-bottom: 12pt"><P STYLE="margin: 0pt"></P><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">CUSIP No. 83422E105</P><P STYLE="margin: 0pt"></P></DIV>
    <!-- Field: /Page -->

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><U>Exhibit 1</U></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><U>JOINT FILING AGREEMENT</U></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">This Joint Filing Agreement,
dated as of February 9, 2018, is by and among RA Capital Management, LLC and Peter
Kolchinsky (the foregoing are collectively referred to herein as the &ldquo;Filers&rdquo;).</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">Each of the Filers
may be required to file with the United States Securities and Exchange Commission a statement on Schedule 13G and/or 13D with respect
to Common Stock of Solid Biosciences Inc. beneficially owned by them from time to time.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">Pursuant to and in
accordance with Rule 13(d)(1)(k) promulgated under the Securities Exchange Act of 1934, as amended, the Filers hereby agree to
file a single statement on Schedule 13G and/or 13D (and any amendments thereto) on behalf of each of such parties, and hereby further
agree to file this Joint Filing Agreement as an exhibit to such statement, as required by such rule.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">This Joint Filing Agreement
may be terminated by any of the Filers upon one week&rsquo;s prior written notice or such lesser period of notice as the Filers
may mutually agree.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">Executed and delivered
as of the date first above written.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">RA CAPITAL MANAGEMENT, LLC</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">By: /s/ Peter Kolchinsky</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">-------------------------------------------------</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">Peter Kolchinsky</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">Manager</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">PETER KOLCHINSKY</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">/s/ Peter Kolchinsky</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3.5in; text-align: justify">-------------------------------------------------</P>



<P STYLE="margin: 0"></P>

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