¹Basic & Clinical Genomics Laboratory, Department of Physiology and Institute for Biomedical Research, The University of Sydney, Sydney, Australia

²Human Nutrition Unit, Department of Biochemistry, The University of Sydney, Sydney, Australia

Correspondence to: B J Morris, Basic & Clinical Genomics Laboratory, Department of Physiology and Institute for Biomedical Research, Building F13, The University of Sydney, NSW 2006, Australia. Email: brianm@physiol.usyd.edu.au

OBJECTIVE: To determine whether the C825T polymorphism of the G-protein 3 subunit gene (GNB3) is associated with overweight and obesity. This polymorphism leads to a splice variant (G3-s) with higher activity and very strong association with essential hypertension.

DESIGN: A cross-sectional case-control study.

SUBJECTS: The sets of affected and control British/European Caucasian subjects used were: (i) an obesity clinic group most of whom had 'morbid obesity' (mean body mass index (BMI) for group=43±8 kg/m²) and non-obese controls (BMI£30); (ii) a group of overweight/obese healthy normotensive community volunteers (BMI>25; mean 29±5) and controls (BMI£25; mean 23±1); (iii) a group of overweight/obese hypertensive patients (BMI>25; mean 30±4) and lean hypertensive controls (BMI£25; mean=23±2).

MEASUREMENTS: BMI, blood pressure, serum lipids, alleles of GNB3 polymorphism.

RESULTS: Compared with control, frequency of the T allele in obese subjects was higher by 12% in (i), 17% in (ii) and 28% in (iii), but the differences were not statistically significant. Slight tracking of the T allele with elevation in BMI was, however, observed, in the obesity clinic group (P=0.018).

CONCLUSION: The C825T splice variant of GNB3 makes little if any contribution to obesity in the groups we tested.

International Journal of Obesity (2001) 25, 777-780

body mass index; association study; molecular genetics; G-proteins