Segregation analysis of fat mass and other body composition measures derived from underwater weighing.
Segregation patterns of three body composition measures which were derived from underwater weighing were evaluated in a random sample of 176 French-Canadian families. Two of the variables can be considered as primary partitions of weight (fat mass [FM] and fat-free mass [FFM]), while the remaining variable (percent body fat [%BF]) is a derived index combining the measures of both fat and fat-free weight. This study represents the first report investigating major gene effects for these measures. Segregation analyses revealed that a major locus hypothesis could not be rejected for two of the three phenotypes. The single exception was FFM, for which nearly 60% of the variance was accounted for by a non-Mendelian major effect, which may reflect environmentally based commingling or may be in part a function of gene-environment interactions or correlations. In contrast to the results for FFM, the results for each of FM and %BF were similar and suggested a major locus which accounted for 45% of the variance, with an additional 22%-26% due to a multifactorial component. Given the similarity of the major gene characteristics for these two phenotypes, the possibility that the same gene underlies both measures warrants investigation. A reasonable hypothesis is to consider genes that may influence nutrient partitioning, as the family of candidate genes to receive the major attention.
Rice
T
T
Division of Biostatistics, Washington University School of Medicine, St. Louis, MO 63110.
Borecki
I B
IB
Bouchard
C
C
Rao
D C
DC
D000273:Adipose Tissue; D000293:Adolescent; D000328:Adult; D001823:Body Composition / Q000235:genetics*; D015992:Body Mass Index; D001835:Body Weight / Q000235:genetics*; D016009:Chi-Square Distribution; D002648:Child; D005260:Female; D005821:Genetic Techniques; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D008957:Models, Genetic; D009765:Obesity / Q000235:genetics*; D010641:Phenotype; D012044:Regression Analysis