GENETIC INFLUENCES ON CENTRAL ABDOMINAL FAT - A TWIN STUDY

INTRODUCTION: Recent studies of regional fat distribution have focused on the clinical importance of central abdominal obesity. Central adip osity is strongly related to insulin resistance, non-insulin dependent diabetes mellitus (NIDDM), dyslipidaemia and cardiovascular disease. While significant genetic influences on body mass index (BMI), total b ody and subcutaneous fat have been demonstrated, the inheritance of ce ntral abdominal obesity, has not been studied. OBJECTIVE: To assess ge netic effects on regional fat distribution and associated metabolic pa rameters. DESIGN AND SUBJECTS: We directly measured total body, centra l abdominal (C-abd) and non-abdominal fat using dual energy X-ray abso rptiometry in 50 monozygotic (MZ) and 36 dizygotic (DZ) female twins, of age (mean +/- SD), 44 +/- 12 and 47 +/- 14 y; BMI 24 +/- 5 and 24 /- 3 kg/m(2); C-abd fat 33 +/- 9 and 32 +/- 9%, respectively. Total va riance in all parameters was independent of zygosity and genetic analy ses of regional adiposity were performed before and after adjusting fo r age and percentage total body fat. RESULTS: A genetic influence was observed on the population variance in total fat, C-abd fat (C-abd fat rMZ = 0.66 vs rDZ = 0.20, p = 0.03) and non abdominal fat. After adju sting C-abd fat for age and total body fat there was a independent gen etic influence on C-abd fat accounting for approximately 70% of the po pulation variance (rMZ = 0.61 vs rDZ = 0.40, p = 0.001). CONCLUSION: T he majority of inter-subject variance in central abdominal fat in non- obese individuals is due to genetic factors. The inheritance of abdomi nal obesity, with its associated metabolic consequences, may contribut e to the familial aggregation of insulin resistance, diabetes and card iovascular disease.