Alternative primers for DYS391 typing: advantages of their application to forensic genetics

The amplification of the STR DYS391, using the primers described in the Gen ome Data Base (GDB: G00-365-251), shows not only an additional band to the Y-specific one in males with a size range of 26 bp less than those of DYS39 1 locus alleles, bur also a polymorphic pattern in females in the same size range as the additional band observed in males. The DYS391 pattern in fami lies reflects a Y-specific linked locus and also a polymorphic X locus with an X-linked pattern of inheritance, A first screening in the X homologous locus allowed the identification of five different alleles. Allele frequenc ies were explored in different population groups for both the Y locus and t he homologous locus in the X chromosome showing a similar allele distributi on pattern in the X and Y homologous loci, An alternative reverse primer wa s designed to amplify the Y-chromosome specific STR in order to improve the specificity and applicability of this system to forensic genetics. Compara tive results of the amplification with the new and the previously described primers proved that with this new primer there is a substantial increase i n the specificity of the amplification. Moreover, a smaller fragment is amp lified with a size out of the range of the alleles of the other Y-STRs usua lly used in forensic applications, therefore simplifying its inclusion in m ultiplex systems. (C) 2000 Elsevier Science Ireland Ltd. All rights reserve d.