Heritability of obesity-related traits among Nigerians, Jamaicans and US black people

OBJECTIVE: The mean values for anthropometric traits vary across population groups and this variation is clearly determined for the most part by the environment. The familiarity of anthropometric traits also varies in reports from different populations, although this variation has not been shown to follow a consistent pattern. To examine whether heritability is influenced by socio-cultural factors, we conducted a cross-cultural study of populations of the African diaspora. PARTICIPANTS: Data were collected on 1868 family members from Nigeria, 623 from Jamaica and 2132 from metropolitan Chicago, IL, USA. MEASUREMENTS: Height and weight were measured and body mass index (kg/m²) calculated. Fat-free mass, fat mass and percentage body fat were estimated using bioelectrical impedance analysis. Plasma leptin concentrations were also measured. The proportion of variance attributable to additive genetic and non-shared environmental components was estimated with the maximum likelihood variance decomposition method. RESULTS: Mean values for all anthropometric traits increased along the socio-cultural gradient, and obesity increased from 5% in Nigeria to 23% in Jamaica and 39% in the USA. Within populations the relationships among traits both within individuals and within families were highly consistent. Heritability estimates for weight, body mass index, fat mass and percentage body fat were approximately 50% for all groups. Heritability for height was lower in Nigeria (62%) than in Jamaica (74%) or the US (87%). CONCLUSION: The familial patterns of body size and energy storage appear to be consistent in these genetically related populations across a wide range of environmental conditions.