Sequence analysis and population data of short tandem repeat polymorphisms at loci D8S639 and D11S488

Abstract

Short tandem repeat loci are ideal markers for forensic and paternity case work. A high degree of polymorphism, as determined by gross length measurement, is very often due to complex underlying sequence variation. In the present study, we have studied the sequence structure and population genetics of two short tandem repeat polymorphisms at loci D8S639 and D11S488 in German Caucasians from the region of Hesse. Sequence data revealed a considerable polymorphism at both loci. Locus D8S639 is characterized by a tetranucleotide (AGAT)n repeat pattern with (GAT) and (AGGT) repeats dispersed throughout several alleles. These microvariations lead to alleles differing by one base pair or alleles of identical size. At locus D8S639 we observed 17 allelic lengths comprising 25 different alleles. Alleles at locus D11S488 possess a compound repeat region consisting of (AAAG)n and (GAAG)n repeats. At locus D11S488 we observed 15 allelic lengths with a total of 24 alleles. Allelic lengths increased in size by 4bp increments corresponding to the addition of one tetranucleotide repeat unit. Population data of loci D8S639 and D11S488 revealed a high polymorphism with heterozygosity rates of 0.85 (D8S639) and 0.91 (D11S488).