Japanese population study of a Y-linked dinucleotide repeat DNA polymorphism.

A polymorphic CA repeats (YCA II) was previously reported on the human Y chromosome. We have used a simple technique based on polymerase chain reaction amplification followed by native polyacrylamide gel electrophoresis to study the inheritance, the genetic stability, and the allele frequency distribution of this polymorphism in the Japanese. We found seven haplotypes which were tentatively designated as: A[(CA)19/(CA)21], B[(CA)19/(CA)22], C[(CA)19/(CA)23], D[(CA)19/(CA)19], E[(CA)21/(CA)21], F[(CA)22/(CA)22], and G[(CA)23/(CA)23]. The frequencies of these haplotypes were: A, 0.21; B, 0.29; C, 0.37; D, 0.02; E, 0.02; F, 0.07; G, 0.01. There was complete concordance with each father-son pairs. The results indicate the dinucleotide system YCA II is very useful for investigation of forensic samples, especially mixed stains in sexual offence cases.