Simultaneous determination of STR polymorphism and a new nucleotide substitution in its flanking region at the CD4 locus.

In the course of the investigation of a pentanucleotide repeat polymorphism at the human CD4 locus, a C-A transversion was found at the position corresponding to the 3' end of the original forward primer presented by Edwards et al. (1). In the present study, the simultaneous determination of the new sequence polymorphism and the pentanucleotide repeat polymorphism at the CD4 locus was attempted. To achieve this purpose, we adopted amplified product length polymorphism (APLP) analysis and designed some new allele-specific forward primers tagged with non-complementary nucleotides differing in length. A total of 646 DNA samples from peripheral blood of Japanese, Chinese and German populations were investigated. Although the C-A transversion was restricted to CD4*5, a new subtype allele with A and 5 repeats, designated CD4*5A, was observed at polymorphic frequencies in the three populations. The simultaneous genotyping by APLP analysis resulted in dramatically increased heterozygosity and discriminating power of the human CD4 locus.