the study showed that the first variant was not associated with menstrual disorders, whereas the second variant might be implicated in menstrual disorders in some Singapore Chinese women.

Luteinizing hormone (LH) stimulates the interstitial Leydig cells to produce testosterone, which is essential for spermatogenesis. Abnormalities in the function of LH may affect the process of spermatogenesis and thus result in infertility. The aim of this study was to determine the association of three known variants of LH (Gln54Arg [Trp8Arg; Ile15Thr] and Gly102Ser) with male infertility. A total of 145 infertile men and 200 healthy fertile men were recruited and screened for the presence of these three LH variants. The Gln54Arg variant could not be detected in either of the groups studied. Twelve infertile (8.2%) and 15 fertile (7.5%) men were found to carry the [Trp8Ile; I15Thr] variant, but its occurrence did not show any significant difference between the patient and control groups. The Gly102Ser variant was detected in five patients with infertility (3.4%), but not in the control subjects (P = 0.013). This study showed that the Gln54Arg and [Trp8Ile; I15Thr] variants in the LHbeta gene were not associated with male infertility, whereas the Gly102Ser variant might be implicated in infertility in some Singapore Chinese men.

Three populations of Southeast Asia comprising 191 Chinese, 121 Malays and 150 Indians, were studied with respect to two recently described mutant luteinizing hormone (LH) variants using molecular techniques. One of these variants had Trp⁸ to Arg⁸ and Ile¹⁵ to Thr¹⁵ replacements in exon 2 of the LH β-subunit, while the other variant possessed Ser¹⁰² substitution for Gly¹⁰² in exon 3. The exon 2 mutants were in complete linkage disequilibrium. The exon 2 variant had an allele frequency of 0.045 in Chinese, 0.062 in Malays and 0.030 in Indians. The allele frequency of the exon 3 variant was 0.018 in Chinese and null in Malays and Indians. The two LH variants may be markers of interest in studies of disturbed pituitary-gonadal function, menstrual disorders and female infertility.