Subtyping of D20S85 STR alleles by single-strand conformation polymorphism (SSCP) analysis

During a population study of STR locus D20S85, we discovered two types of sequence variations by direct sequencing of the alleles: two transitions each of G to A and A to G occur in the 5' flanking region in the individuals possessing allele 6 and some of those possessing allele 7 [1]. Using single-strand conformation polymorphism (SSCP) analysis, we were able to distinguish two subtypes of allele 7 from each other. This analysis method enables rapid screening for STR alleles of the same length with different sequences, and should find application to other complex STR loci because of the practical advantage of simplicity in comparison to sequencing.