Familial resemblance for anthropometric measurements and relative fat distribution among African Americans

Obesity has emerged as a major public health problem in the African-American community and its determinants are poorly understood. The purpose of this study was to examine familial patterns of the degree of heaviness and of regional fat deposits. Seven anthropometric measurements (height, weight, body mass index [BMI], waist and hip circumferences, waist-to-hip ratio and arm circumferences) were examined in a population sample of African-American nuclear families recruited from the Chicago area. Participants included 162 parent pairs and 114 sets of siblings (a total of 295 sons and daughters). Adjustments to correct for the effect of age and sex were performed separately for parents and siblings and the residuals were transformed to normalized z-scores to calculate intraclass correlations between family members. With the exception of waist-to-hip ratio, all variables showed positive familial resemblance, although the degree and level of statistical significance varied by type of relationship. Significant familial resemblance was observed for peripheral fat deposit, as measured by hip and arm circumferences (range: 0.04 for spouse pairs to 0.42 for daughter pairs), and obesity, as measured by BMI (range: 0.12 for spouses to 0.33 for mother-daughter comparison). Significant sex and generation differences were observed for height and hip. We conclude that African Americans exhibit significant familial resemblance for stature, degree of heaviness and regional fat deposits. Understanding the relative contributions of shared genes and shared environmental factors to the observed familial patterns could yield important insights into the origins of obesity in this high risk population.