Login to Access Video or Poster Abstract: MP07-06
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Introduction

It has been reported that many testis-specific functional genes are drastically expressed during spermatogenesis, and defects in their expression cause male infertility. Haspin, encoding a germ cell-specific protein kinase, was cloned from a subtracted cDNA library constructed from mouse testis. Genomic analyses revealed that mouse Haspin is an intron-less gene located within the 26th intron of the integrin alpha E (Itgae) gene on chromosome 6, which is conserved in rats and humans. It was shown that human HASPIN phosphorylates histone H3 at threonine 3 and is required for this phosphorylation event in mitotic cells. HASPIN is found at the centrosomes and spindles during mitosis, where it integrates the regulation of chromosome and spindle function during mitosis and meiosis. The present study assessed whether HASPIN is a cause of infertility in Japanese males.

Methods

Japanese subjects with nonobstructive infertility (n = 282) were divided into subgroups according to their degree of defective spermatogenesis: 192 (68%) of these patients had nonobstructive azoospermia, while 90 (32%) had severe oligospermia (<5 × 106 cells/ml). The control group consisted of fertile males who had fathered children born at a maternity clinic (n = 262). Their HASPIN coding sequence (CDS) was screened by the direct sequencing of PCR amplified DNA. This study was conducted with approval from the institutional review board and an independent ethics committee at Osaka University.

Results

Polymorphisms were found at 10 positions within the HASPIN CDS. Among those polymorphisms, there were six nt changes causing an amino acid substitution, one insertion (TCCCGACGA) leading to the addition of three amino acids (aspartic acid- aspartic acid-proline: DDP), and three silent mutations. There were no correlations among the polymorphisms in terms of their co-occurrence. Three single nucleotide polymorphisms (SNPs) (c365C > A, c560T > C, and c2205A > G) and the insertion resulting in three additional amino acids (c204-/TCCCGACGA) were identified in Japanese males for the first time. Unexpectedly, c2143G > A (rs376754182) was present only in homozygous form in the infertile group.

Conclusions

In this study, we found 10 polymorphisms within the HASPIN CDS. Among those, 5 were found only in the infertile group, 3 of which were nonsynonymous. These polymorphisms found only in the infertile patients may be a cause of male infertility, although significant differences in the frequencies of the genotypes were not identified. This is the first analysis of HASPIN genetic polymorphisms in male infertile population and these results will contribute significantly to future large-scale studies on the genetic background of infertility in Japanese males and on functional analyses of the role of HASPIN in cell cycle progression.

Funding

none