Major Customers and Concentration of Credit Risk

12 Months Ended

Dec. 31, 2019

Major Customers and Concentration of Credit Risk



Customer	2019 Revenue		% of Total Revenue		2018 Revenue		% of Total Revenue		2017 Revenue		% of Total Revenue
ApolloBio	$	—	—	%	$	23,000,000	75	%	$	—	—	%
AstraZeneca	3,194,877		78		6,850,424		23		22,269,773		53
DARPA	—		—		—		—		9,983,927		24
Roche	—		—		—		—		6,107,254		14
All other, including affiliated entities	917,053		22		631,473		2		3,859,132		9
Total revenue	$	4,111,930	100	%	$	30,481,897	100	%	$	42,220,086	100	%

During the years ended December 31, 2019 and 2018, the Company recognized revenue from various license fees and collaborative research and development agreements. The Company has determined that as of January 1, 2018, accounting for the Company’s various grant agreements falls under the contributions guidance under Subtopic 958-605, Not-for-Profit Entities-Revenue Recognition, which is outside the scope of Topic 606. Beginning on January 1, 2018, all contributions received from current grant agreements have been recorded as a contra-expense as opposed to revenue on the consolidated statements of operations, as discussed in Note 2. During the year ended December 31, 2017, the Company recognized revenue from various license fees, collaborative research and development agreements, grants and government contracts. As of December 31, 2019, $469,000, or 67%, and $161,000, or 23%, of the Company's accounts receivable was attributable to MCDC and AstraZeneca, respectively. As of December 31, 2018, $3.2 million, or 98%, of the Company's accounts receivable was attributable to AstraZeneca.

There is minimal credit risk with these customers based upon collection history, their size and financial condition. Accordingly, the Company does not consider it necessary to record a reserve for uncollectible accounts receivable.