Angiotensin-Converting Enzyme Insertion/Deletion Polymorphism, Lower Extremity Strength, and Physical Performance in Older Adults.

Abstract

Evidence for associations between the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene and physical performance is conflicting. Furthermore, investigations of relationships between lower extremity strength and physical performance have usually not considered the role of the ACE genotype, and it is unclear whether there are variations in relationships between lower extremity strength and physical performance among ACE genotypes in older adults. The objectives of this study were to investigate associations between the ACE I/D polymorphism and physical performance and to determine whether relationships between lower extremity strength and physical performance vary among ACE genotypes in older adults. This was a cross-sectional observational study. Community-dwelling adults (N=88) who were at least 60 years old completed physical performance and lower extremity strength tests. After DNA was extracted from saliva, ACE I/D polymorphism genotyping was done. The Spearman rank order correlation coefficient was used to examine associations between lower extremity strength and physical performance within ACE genotype subgroups. Analysis of covariance and linear regression were used to examine ACE genotype and ACE genotype×lower extremity strength interaction effects in relation to physical performance. Genotype-specific correlation coefficients exhibited substantial variation among ACE genotype subgroups; however, differences did not attain statistical significance. Statistically significant genotype×lower extremity strength interaction effects in relation to physical performance were detected. The cross-sectional design precludes inferring causal relationships between strength and performance. The small sample size contributed to limited power to detect additional interaction effects and to detect statistically significant differences between correlation coefficients among ACE genotype subgroups. The ACE I/D polymorphism is, interactively with lower extremity strength, associated with physical performance. Genotype-specific correlation coefficients and ACE genotype×lower extremity strength interaction effects on physical performance are consistent with variations in relationships between lower extremity strength and performance among ACE genotype subgroups.