ACE I/D POLYMORPHISM AND SKELETAL MUSCLE CHARACTERISTICS IN THE QUEBEC AND HERITAGE FAMILY STUDIES

The I allele of the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism has been associated with endurance performance in some studies, but failure to find evidence of association with maximal oxygen uptake has led to the suggestion that the association could be modulated by the impact of the polymorphism on skeletal muscle metabolic characteristics. PURPOSE To examine the association between the ACE I/D polymorphim and skeletal muscle characteristics in sedentary subjects from the Quebec (QFS) and HERITAGE Family Studies. METHODS Muscle biopsies of the vastus lateralis were obtained in a total of 117 subjects from QFS (n = 39) and HERITAGE (n = 78) cohorts. The ACE I/D polymorphism was genotyped and tested for association with fiber type characteristics, capillary density and activities of glycolytic (PFK, PHOS, CK) and oxydative (COX, CS, HADH, GAPDH, CPT) enzymes after adjustment for age, sex, cohort effects and maximal oxygen uptake using a procedure taking into account the non-independence of subjects within families. RESULTS The genotype frequencies were not significantly different between QFS (II = 0.26; ID = 0.38; DD = 0.36) and HERITAGE (II = 0.31; ID = 0.41; DD = 0.28) cohorts. Muscle CK was found to be higher (p = 0.02) in II (mean ± SEM: 399 ± 10) compared to DD (362 ± 13) subjects. In the HERITAGE cohort, the association was stronger (p = 0.007), with CK activity values of 423 ± 14 and 376 ± 16 in II and DD subjects, respectively. No association was found with the other skeletal muscle phenotypes. CONCLUSION These results suggest that the ACE I/D polymorphism could affect skeletal muscle creatine kinase activity, which could partly explain the association previously reported between the ACE gene and muscular performance. Supported by Canadian Institutes of Health Research and National Heart, Lung and Blood Institute, NIH.