Examination of Y-STR mutations in sex chromosomal abnormality in forensic cases

Abstract 

The Y-STR typing was carried out on eight DNA samples (three from criminal cases) demonstrating Klinefelter’s syndrome. STR types in the X chromosome were randomly distributed. However, some Y-STR markers were distributed within the normal range but restricted to only one or two specific alleles, that is, some specific haplotypes were found in Klinefelter’s syndrome. In addition, a single nucleotide polymorphism in DYS390 (transversion of G to A at the 28th position downstream of tandem repeats) was detected in Klinefelter samples. This Y-STR polymorphism and restricted Y-STR alleles in Klinefelter’s syndrome is not known, but it might be related to the genesis of Klinefelter’s syndrome. We also found that extended standard haplotypes of these samples are extremely rare in the normal population, according to the Y-STR haplotype reference database (YHRD). The extended standard haplotype database in a Japanese population is also reported. In 100 unrelated Japanese, 89 haplotypes were observed, and the haplotype diversity was calculated to be 0.9866.

Keywords:  Criminal case, DNA testing, Y-STR haplotype, Short tandem repeats, Multiplex PCR, Klinefelter’s syndrome