D13S317 frequency distribution by population of the nine flanking region motifs identified in N = 1036. The first row of 5’ and 3’ flanking sequence is consistent with GRCh38, and is the most common sequence found in this data set. Dots in subsequent rows represent bases matching the first row. Flanking polymorphisms are identified by numbers one through eight in the bottom row: 1) rs73250432 C>T, 2) rs146621667 G>A, 3) rs9546005 A>T, 4) rs202043589 A>T, 5) rs1442523705 delATCT, 6) ss2137543825 A>G, 7) rs561167308 delTCTG, and 8) rs768323113 C>T. Variation in repeat region length, combined with these flanking region polymorphisms, results in 32 sequence-based alleles at this locus. Three additional D13S317 alleles in this data set result from repeat region sequence variants, each observed once, and have been excluded from this figure.