Relative roles of heredity and physical activity in adolescence and adulthood on blood pressure.

Part of the association between physical activity and low blood pressure (BP) may be a consequence of genetic selection. We investigated the association of genetic factors and physical activity in adolescence and adulthood with BP. BP was measured with a Finapres device in 71 monozygotic and 104 dizygotic male twin pairs using no antihypertensive medication. Subjects' mean age was 50.4 yr (range 40-72 yr). Subjects were interviewed about their lifetime exercise and other health habits. Exercise was classified as aerobic, power, or other, and these were further divided into adolescence (12-20 yr of age), the previous year, and lifetime. Genetic modeling was conducted to estimate genetic and environmental components of variance of systolic and diastolic BP. Aerobic exercise in adolescence and high-intensity aerobic exercise throughout the lifetime were associated with low diastolic BP in adulthood. Of the variance in diastolic BP, genetic factors accounted for 35% and aerobic exercise in adolescence for 5%. For systolic BP, genetic factors accounted for 39% of the variance. In turn, genetic factors accounted for 44% of the variance in aerobic exercise in adolescence. The genetic factors in part accounting for the variance in diastolic BP and those in part accounting for variance in aerobic exercise in adolescence were correlated. The association between aerobic exercise in adolescence and low diastolic BP in adulthood is a new finding, as is the observation that the factors partly share the same genes.

Genome-wide linkage scan for physical activity levels in the Quebec Family study.

PURPOSE AND METHODS: It is commonly recognized that there is familial aggregation for physical activity level. However, the genes and sequence variants responsible for the familial clustering have not been investigated. We performed a genome-wide linkage scan based on 432 markers typed in 767 subjects from 207 families of the Quebec Family study with the aim of identifying loci affecting physical activity levels. Four physical activity level phenotypes were used. RESULTS: Promising evidence of linkage (P < 0.0023) was found for physical inactivity on chromosome 2p22-p16. Suggestive linkages (0.0023

A dopamine D2 receptor gene polymorphism and physical activity in two family studies.

A role for dopamine neurotransmission in the regulation of motor activity and reinforcement of behavior is supported by considerable evidence. We studied the association between a marker in the dopamine D2 receptor gene (DRD2) and physical activity level in two cohorts. A first cohort consisted of 721 participants from 161 families of the Quebec Family Study (QFS). Physical activity phenotypes were obtained from a three-day diary and a questionnaire probing physical activity during the past year. The second cohort was the HERITAGE Family Study (HERITAGE), which included 275 Black and 497 White participants from 228 families, among whom past year leisure time and occupational physical activity were probed. A fragment length polymorphism in exon 6 of the DRD2 gene was detected by the polymerase chain reaction (PCR) and NcoI digestion. Frequencies for the T and C alleles were 28% and 72% in the QFS. In the QFS, TT homozygote women had 25% and 34% lower age and BMI-adjusted physical activity level during the past year, compared to CC homozygotes and CT heterozygotes (F=4.42, P=.016). The DRD2 genotype was not associated with the QFS phenotypes obtained from the three-day diary. In the HERITAGE, the frequency of the T allele was 30% among Whites and 63% among Blacks. Similarly, the TT homozygote White women had 29-38% lower sports index (F=4.09, P=.023) and 27-33% lower work index (F=6.23, P=.004) than the CC homozygotes and CT heterozygotes. The results suggest that DNA sequence variation in the DRD2 gene is associated with physical activity levels among White women.