Association of Long Polyglutamine Tracts in Exon 1 of the Androgen Receptor Gene with Idiopathic Male Infertility

Ramin Radpour ^*, XioYan Zhong , Ali Tavasoly , Sanaz Solati , and Wolfgan Holzgreve

^* To whom correspondence should be addressed. E-mail: rradpour{at}royaninstitute.org.

It is estimated that 10%-20% of patients with male infertilitycould have reduced androgen receptor function as a result oflong polyglutamine tracts. To study the association of CAG trinucleotiderepeats in the androgen receptor gene with idiopathic male infertilityin Iranian population we performed a case-control study of 178Iranian males with idiopathic infertility which were excludedfor androgen receptor mutations and 210 fertile males as control.We identified 13 different alleles in the infertile group rangingfrom 18 to 32 CAG repeats and 11 different alleles in controlgroups ranging from 16 to 28. The length of the CAG repeat segmentwas evaluated using PCR-sequencing of exon 1 and PCR-SSCP ofexons 2-8. The mean length of CAG repeats was significantlydifferent between infertile and fertile groups (24.13 ±1.64 vs. 20.55 ± 2.73). The odds ratio for male infertilitywas higher for patients with $≥$ 26 CAG repeat than in those with<26 CAG repeats. Long ( $≥$ 26) androgen receptor CAG alleles,which are found in up to 38% of infertile males, are associatedwith male infertility and defective spermatogenesis.

Key words: Androgen receptor gene • CAG repeats • male idiopathic infertility