Genetic Polymorphisms within The Intronless ACTL7A and ACTL7B Genes Encoding Spermatogenesis-Specific Actin-Like Proteins in Japanese Males.

Actins play essential roles in cellular morphogenesis. In mice, the and 2 genes, which encode actin-like proteins, are specifically expressed in haploid germ cells. Both and have also been cloned and studied. The orthologous genes in humans are present on chromosome 9q31.3 as intronless genes. Defects of germ cell-specific genes can introduce infertility without somatic function impairment. We determined T-ACTIN1 and 2, specifically expressed in the testis using reverse-transcription polymerase chain reaction (RT-PCR). To examine whether genetic polymorphisms of the and 2 genes are associated with male infertility, we screened for and 2 polymorphisms by direct sequencing of DNA from 282 sterile and 89 fertile Japanese men. We identified five and six single nucleotide polymorphisms (SNPs) in the and 2 regions of the sterile and fertile subjects respectively. Among these genetic polymorphisms was a novel SNP that was not in the National Center for Biotechnology Information SNP database. Although we could not determine whether these SNPs cause infertility, the prevalence of these genetic polymorphisms may be useful for analyzing polymorphisms in future largescale genetic analyses.