Starting in March 2018, SNP variation features will no longer be in RefSeq genome assembly records – chromosome and contig records with NC_, NT_, NW_ and AC_ accession prefixes. This change affects both the ASN.1 and flatfile records. Because the number of variants is already enormous and still growing, removing SNP features from these large genomic records will significantly reduce the size of RefSeq FTP files and make downloading and processing easier. We will continue to include SNPs on NG_-prefixed genomic records, and transcript (NM_, NR_, XM_, XR_) and protein (NP_, XP_, YP_) sequences.
Reminder: As of September 2017, NCBI has stopped accepting submissions for non-human SNPs in dbSNP and dbVar. RefSeq flatfiles will stop presenting non-human variant data in November 2017.
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