Introduction: Recent studies of regional fat distribution have focused on the clinical importance of central abdominal obesity. Central adiposity 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 body and subcutaneous fat have been demonstrated, the inheritance of central abdominal obesity, has not been studied.
Objective: To assess genetic effects on regional fat distribution and associated metabolic parameters.
Design and subjects: We directly measured total body, central abdominal (C-abd) and non-abdominal fat using dual energy X-ray absorptiometry 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/m2; C-abd fat 33 +/- 9 and 32 +/- 9%, respectively. Total variance in all parameters was independent of zygosity and genetic analyses of regional adiposity were performed before and after adjusting for 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 adjusting C-abd fat for age and total body fat there was a independent genetic influence on C-abd fat accounting for approximately 70% of the population variance (rMZ = 0.61 vs rDZ = 0.40, p = 0.001).
Conclusion: The majority of inter-subject variance in central abdominal fat in non-obese individuals is due to genetic factors. The inheritance of abdominal obesity, with its associated metabolic consequences, may contribute to the familial aggregation of insulin resistance, diabetes and cardiovascular disease.