Tryptophan 64 --> arginine polymorphism of beta-3-adrenergic receptor in Chilean women with polycystic ovary syndrome.

OBJECTIVE

To establish the frequency of the Trp64Arg polymorphism of the beta3 adrenergic receptor (ADRB3) in women with polycystic ovary syndrome (PCOS) from a Chilean population, focusing particularly on the interaction with body weight. In addition, we evaluated the relationship of the Trp64Arg variant with other metabolic components of this syndrome.

PATIENTS AND DESIGN

In a case-control design study, a total of 106 women with clinical and hormonal evidence of PCOS and 82 healthy women (HW) were evaluated.

MEASUREMENTS

An oral glucose tolerance test (OGTT) was performed and serum glucose and insulin were measured before the glucose load and 30, 60, 90 and 120 min after. Lipid profile was determined in the basal sample. Insulin resistance was assessed by the homeostatic model assessment (HOMA(IR)) and insulin sensitivity index (ISI) composite. A polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis was performed to determine the Trp64Arg polymorphism of ADRB3.

RESULTS

The frequency of the heterozygous condition was similar between PCOS and HW (39%vs. 35%). Only two subjects were homozygous for arginine, both belonging to the PCOS group and having a body mass index (BMI) > 30 kg/m2. In the crude analysis, hypothesis tests and odds ratios show that there is no evidence of association between the ADRB3 Trp64Arg variant and PCOS (P = 0.47). Moreover, when data were stratified by BMI categories, the statistical test for interaction between Trp64 carrier status and obesity was not significant (P = 0.29). This variant was present in 52% of the obese PCOS patients and 40% of the obese HW. In normal weight and obese PCOS carriers, the presence of the Trp64Arg variant was associated with high triglyceride (TG) levels. A major effect of the Trp64Arg variant on insulin resistance parameters could not be demonstrated.

CONCLUSIONS

The frequency of the Trp64Arg polymorphism was similar in healthy women and PCOS women, and a possible interaction between the effect of this variant and obesity in PCOS could not be demonstrated. However, our results showed an association between triglyceride levels and the presence of this genetic variant in PCOS women.