6. ACCOUNTS RECEIVABLE AND RESERVES FOR PRODUCT SALES

The Company’s accounts receivable arise from product sales, government research contracts and other grants. They are generally stated at the invoiced amount and do not bear interest.

The accounts receivable from product sales represents receivables due from the Company’s specialty distributor and specialty pharmacies. The Company monitors the financial performance and creditworthiness of its customers so that it can properly assess and respond to changes in the customers’ credit profiles. The Company provides reserves against trade receivables for estimated losses that may result from a customer’s inability to pay. Amounts determined to be uncollectible are written-off against the established reserve. As of March 31, 2017, the credit profiles for the Company’s customers are deemed to be in good standing and write-offs of accounts receivable are not considered necessary. Historically, no accounts receivable amounts related to government research contracts and other grants have been written off and, thus, an allowance for doubtful accounts receivable related to government research contracts and other grants is not considered necessary.

The following table summarizes the components of the Company’s accounts receivable for the periods indicated:

	As of March 31, 2017		As of December 31, 2016
	(in thousands)
Trade receivables	$	11,349	$	4,002
Unbilled receivables		929		1,226
Total accounts receivable	$	12,278	$	5,228

The balance for unbilled receivables for both periods presented is subject to government audit and will not be collected until the completion of the audit. The decrease in unbilled receivables is related to contract finalization and subsequent collection of the European Union SKIP-NMD Agreement related to the Company’s exon 53 product candidate.

The following table summarizes an analysis of the change in reserves for discounts and allowances for the periods indicated:

	Chargebacks			Rebates			Other Accruals			Total
	(in thousands)
Balance, as of December 31, 2016	$	1		$	238		$	67		$	306
Provision		256			608			132			996
Payments/credits		(152	)		(88	)		(82	)		(322	)
Balance, as of March 31, 2017	$	105		$	758		$	117		$	980

The following table summarizes the total reserves above included in the Company’s unaudited condensed consolidated balance sheets for the periods indicated:

	As of March 31, 2017		As of December 31, 2016
	(in thousands)
Reduction to accounts receivable	$	105	$	1
Component of accrued expenses		875		305
Total reserves	$	980	$	306