The ACE Gene I/D Polymorphism and Physical Performance Correlations Among Community-Dwelling Older Adults

Abstract

Angiotensin converting enzyme (ACE) (EC 3.4.15.1) plays a vital role in maintaining blood pressure and cardiovascular health as part of the renin-angiotensin-aldosterone system (RAAS) (Schmieder et al., 2007). ACE functions by cleaving angiotensin I (Ang I) to produce angiotensin II (Ang II), an active vasoconstrictor and important part of RAAS regulation, and also by inactivating brandykinin, a vasodilator (Harrison and Acharya, 2014). A major polymorphism of ACE occurs in intron 16, where there can be an Alu sequence inserted, resulting in two different alleles: one containing the insertion (I- insertion) and one without it(D- deletion) (Harrison and Acharya, 2014). The D allele of ACE has been shown to produce more mRNA than the I allele (Suehiro et al., 2004), while the I/D polymorphism has been linked with nearly half the variance in serum ACE levels between individuals (Rigat et al., 1990). The brain has independent ACE expression, and the I allele has been linked with a 70% increase in ACE promoter transcription in neuro (Wu enst al., 2013). This apparent difference in ACE expression between the brain and the periphery within the same genotype, and the differences in expression between genotypes, likely have an effect on the cardiovascular and musculoskeletal systems where ACE activity is involved. This study attempted to examine these effects through the differential significant correlations of physical performance and strength measurements seen between the genotype groups. The study involved 88 participants who underwent physical assessments and ACE genotype analysis. The results showed distinct differences in significant correlations between the genotype groups. Balance measure were significantly correlated with strength in the I/I and I/D groups, but not in the D/D group. Stepping also had significant correlations with strength in the I/I and I/D groups not seen in D/D, but significant correlations between gait and strength were seen in I/D and D/D but not I/I. Additionally, the study found a lack of significant correlations between tests like the Sit to Stand (STS) test and strength in the I/I group, and few significant correlations with strength in the D/D, suggesting that the process of administering tests to evaluate strength should consider ACE genotype.