Polymorphism of the β3-adrenergic receptor gene and weight gain in pregnant diabetic women

Abstract

Inappropriate body weight gain during pregnancy has critical effects on the outcome for both mother and fetus. Therefore, body weight gain is an important issue in the management of pregnancy in women with diabetes. A Trp64Arg substitution in the β3-AR gene has been reported to be associated with body weight gain and obesity in non-insulin-dependent diabetes mellitus (NIDDM) subjects. The aim of this study was to elucidate the contribution of the β3-AR gene to body weight gain during pregnancy in subjects with diabetes. We analyzed 199 diabetic patients (NIDDM/IDDM; 131/68) and patient data was obtained from the first delivery of each individual. The mean age at diagnosis of diabetes was 22.9±7.5 years (mean±S.D.) and the mean age at delivery was 29.8±4.5 years. A polymorphism of the β3-AR gene was detected by PCR-RFLP using Bst OI, which recognizes a Trp64Arg substitution. The frequency of the Trp64Arg allele was 0.15 in NIDDM and 0.17 in IDDM. Among the NIDDM subjects, excess weight gain during pregnancy, as defined by maximum BMI during pregnancy minus basal BMI before pregnancy exceeding five, was observed in 12.2% of the wild-type patients, 19.2% of heterozygotes and 28.6% of homozygotes. Homozygous subjects with NIDDM tended to show excess weight gain during pregnancy, however, this trend did not reach significance. None of the IDDM homozygotes showed excess weight gain. From our study, this β3-AR gene polymorphism cannot be excluded as a contributing factor to excess weight gain during pregnancy in NIDDM subjects.