Quantitative trait locus on 15q for a metabolic syndrome variable derived from factor analysis

The metabolic syndrome represents a cluster of cardiovascular risk factors co-occurring in the same individual. The aim of this study was to identify chromosomal regions encoding genes predisposing to the metabolic syndrome using composite factors derived from maximum likelihood-based factor analysis. Genetic data were obtained from the Quebec Family Study and included 707 subjects from 264 nuclear families. Factor analyses were performed on eight metabolic syndrome-related phenotypes including waist circumference; BMI; systolic and diastolic blood pressure; and plasma insulin, glucose, triglyceride, and high-density lipoprotein-cholesterol levels. Three factors were identified and interpreted as general metabolic syndrome, blood pressure, and blood lipids, respectively. The general metabolic syndrome factor had high factor loadings (>0.4) for all phenotypes and explained 42% of the total variance, and family membership accounted for 45.6% of the factor variance. A genome-wide linkage scan performed with this first factor revealed the existence of a quantitative trait locus on chromosome 15 (86 cM) with a logarithm of odds score of 3.15. Suggestive evidence of linkage (logarithm of odds > 1.75) was also observed on chromosomes 1p, 3p, 3q, 6q, 7p, 19q, and 21q. These quantitative trait loci may harbor genes contributing to the clustering of the metabolic syndrome-related phenotypes.