Analysis of 21 autosomal STRs in Saudi Arabia reveals population structure and the influence of consanguinity

•GlobalFiler (21-STR) genotypes reported for 523 Saudi Arabian males.•Significant differences in allele frequencies among five geographical sub-regions.•Heterozygote deficiency observed at nearly all loci in all regions, likely reflecting history of consanguineous marriage.•Autosomal sub-regional pattern contrasts with previously described pattern of Y-STR variation in the same samples.•Population structure and heterozygote deficiency should be accounted for in forensic interpretation of Saudi STR profiles.