ASSOCIATION BETWEEN HUMAN TUMOR NECROSIS FACTOR ALPHA (TNF??) GENE POLYMORPHISM AND SUBMAXIMAL POWER OUTPUT IN THE QU??BEC FAMILY STUDY604

The aim of this study was to investigate the relationship between submaximal power output at a heart rate of 170 beats/min (PWC170) assessed from a multistage cycle ergometer test and TNFα (chromosome 6p21.3) gene polymorphism detected by Ncol resulting from a G to A base substitution at position -308. Genetic analysis of restriction fragment length polymorphism was undertaken on 320 individual from 117 families (107 parents and 213 offsprings). PWC170 data were adjusted by regression procedure for the effects of age and sex, and were expressed per kg body weight (PWC170KG) or kg fat free mass (PWC170FFM) derived from body density measurements. Using an association study design with unrelated subjects, individuals who were homozygotes for G at position -308 had significantly higher PWC170KG than those who were heterozygotes for the mutation (12.98 ±4.10 vs 11.00±2.72 kpm/kg, P<0.03), but no difference was found for PWC170FFM(P=0.53). The sib-pair linkage analysis procedure with 80 pairs of adult sibs provided no evidence of linkage between the PWC170 phenotypes and the single base polymorphism in the TNFα gene. These results suggest that TNFα gene variability detected with Ncol may be associated with performance in a submaximal power output test adjusted for body mass. However, no linkage relationship could be detected between the performance phenotype and the TNFα marker locus.