Increased prevalence of luteinizing hormone beta-subunit variant in Japanese infertility patients

To determine the frequency of a common luteinizing hormone variant in a Jap anese population and to evaluate its significance in infertility, serum sam ples were collected from 169 healthy non-pregnant Japanese women, 105 healt hy adult Japanese men and 97 female Japanese infertility patients, The lute inizing hormone variant includes two point mutations in the beta-subunit ge ne (Trp(8) to Arg(8) and Ile(15) to Thr(15)). DNA from blood cells was stud ied in 10 healthy women, 10 men and five patients using polymerase chain re action and direct sequencing. In immunoassays, results with a monoclonal an tibody recognizing only the wild-type hormone and a polyclonal antibody rec ognizing the variant as well were compared as a ratio; ratios in heterozygo tes and in individuals with only wild-type alleles ranged from 0.19 to 0.50 and from 0.56 to 1.21, respectively, and 0.50 was considered a 'cut-off' v alue for identifying individuals with the variant. For the larger subject g roups, the frequency of the variant was 9.5% in normals. The mean ratio (0. 80 +/- 0.35) in infertility patients was significantly lower (P < 0.01) tha n in healthy women (1.09 +/- 0.56), and the variant occurred more frequentl y in infertility. patients (16.5%) than in healthy women (8.3%; P < 0.05). The variant was more frequent in patients with ovulatory disorders (43.8%) than other patients (16.0%; P < 0.05).