A Genome-Wide Scan for Body Mass Index among Nigerian Families


Department of Preventive Medicine and Epidemiology, Loyola University Stritch School of Medicine, 2160 South First Ave., Maywood, IL 60153. E-mail: aluke@lumc.edu


Objective: Interest in mapping genetic variants that are associated with obesity remains high because of the increasing prevalence of obesity and its complications worldwide. Data on genetic determinants of obesity in African populations are rare.

Research Methods and Procedures: We have undertaken a genome-wide scan for body mass index (BMI) in 182 Nigerian families that included 769 individuals.

Results: The prevalence of obesity was only 5%, yet polygenic heritability for BMI was in the expected range (0.46 ± 0.07). Tandem repeat markers (402) were typed across the genome with an average map density of 9 cM. Pedigree-based analysis using a variance components linkage model demonstrated evidence for linkage on chromosome 7 (near marker D7S817 at 7p14) with a logarithm of odds (LOD) score of 3.8 and on chromosome 11 (marker D11S2000 at 11q22) with an LOD score of 3.3. Weaker evidence for linkage was found on chromosomes 1 (1q21, LOD = 2.2) and 8 (8p22, LOD = 2.3). Several candidate genes, including neuropeptide Y, DRD2, APOA4, lamin A/C, and lipoprotein lipase, lie in or close to the chromosomal regions where strong linkage signals were found.

Discussion: The findings of this study suggest that, as in other populations with higher prevalences of obesity, positive linkage signals can be found on genome scans for obesity-related traits. Follow-up studies may be warranted to investigate these linkages, especially the one on chromosome 11, which has been reported in a population at the opposite end of the BMI distribution.