Objective: To investigate the correlation of C/T single nucleotide polymorphism at exon 17 in tyrosine kinase domain of insulin receptor gene with polycystic ovary syndrome (PCOS).
Methods: One hundred and twenty patients with PCOS (PCOS group) and 40 normal females (control group) were included and the 1058 site single nucleotide polymorphism at exon 17 of insulin receptor gene (INSR) was detected with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The baseline parameters including levels of serum follicular stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), estradiol (E(2)), testosterone (T) and lipid, as well as the body mass index (BMI) and waist/hip ratio (WHR) were measured. Glucose tolerance and insulin releasing before and after loading with 75 g of glucose were also assayed.
Results: (1) BMI (25 +/- 4 vs. 23 +/- 3, P < 0.01), WHR (0.82 +/- 0.06 vs. 0.79 +/- 0.07, P < 0.05), LH [(9.2 +/- 6.1) U/L vs. (4.4 +/- 1.6) U/L, P < 0.01], T [(1.9 +/- 0.9) nmol/L vs. (1.0 +/- 0.6) nmol/L, P < 0.01] and E(2) [(205 +/- 119) pmol/L vs. (143 +/- 75) pmol/L, P < 0.01] of PCOS group were higher than those of control group. (2) The blood sugar and insulin levels of fasting, 30 min, 60 min, 120 min after glucose loading in obese PCOS (BMI >/= 25 kg/m(2)) were significantly higher than those in the non-obese PCOS (BMI < 25 kg/m(2)). (3) C/T single nucleotide polymorphism frequency at exon 17 of INSR in patients with PCOS was significantly higher than that in normal female (41% vs. 12.5%, P < 0.01). There was a significant difference between the frequency in non-obese PCOS (52.2%) and obese PCOS (25.5%, P < 0.01). (4) BMI in patients with T allele 23 +/- 3 of INSR single nucleotide polymorphism was lower than that with C allele (26 +/- 4, P < 0.05).
Conclusions: (1) The body weight and gene single nucleotide polymorphism of INSR may play an important role in the occurrence of insulin resistance in patients with PCOS. (2) The 1058 site nucleotide polymorphism of insulin receptor gene is one of the susceptibility genes in patients with PCOS, especially in non-obese PCOS patients.