Objective: To investigate the relationship of (TAAAA)n repeat polymorphism in the promoter of the sex hormone-binding globulin (SHBG) gene and SHBG serum levels to the glucose metabolic status of Chinese polycystic ovary syndrome (PCOS) patients in Shandong province.
Methods: GeneScan method was used to detect and identify (TAAAA)n repeat number (alleles) and genotypes for 156 controls and 157 patients who were divided into normal glucose tolerance without hyperinsulinemia (NIR group) and with hyperinsulinemia (HI group) and abnormal glucose metabolic (AGM) group according to the results of oral glucose test and insulin resistant test; IRMA was used to measure serum SHBG for part of them.
Results: Five alleles containing (TAAAA) 6-10 repeats and 14 genotypes including 6/6, 6/7, 6/8, 6/9, 6/10, 7/7, 7/8, 7/9, 7/10, 8/8, 8/9, 8/10, 9/9, 9/10 repeats genotypes were present in the subjects. Genotype distribution of 6/10 repeats genotype is lower in PCOS than that in control, and 8/9 repeats genotype vice versa (P < 0.01); among PCOS subgroups, the eight repeat genotypes in NIR group is more frequent than that in HI group (P < 0.01), and 7/9 genotype distribution in AGM group is higher than that in NIR group and HI group(P < 0.05-0.01). The serum SHBG levels in homozygous genotype groups exhibit a sequence of 8/8 > 9/9 > 6/6, 7/7 repeats and the fall of serum SHBG trend is in reversed relation with the increase in body mass index (BMI), Homa-IR, and blood pressure. Serum SHBG levels in AGM exhibit a sequence of HI group < NIR group < control but show no statistical difference between both groups.
Conclusion: This study reveals that the repeat number, alleles, genotypes and their distributions in Chinese women are very different from these in foreigners. Some special genotypes and low serum SHBG levels may be associated with PCOS and its glucose metabolic status; some special genotypes may influence Chinese serum SHBG and need more studies, but both SHBG gene polymorphism genotype and serum SHBG are not good indicators to find out the PCOS individual at high risk.