Relationship between sarcopenia and CTN3 R577X gene in older adults

Sarcopenia is characterized by decreased muscle strength, mass and function with an increased risk of adverse outcomes. We aimed to evaluate whether there is a relationship between ACTN3 R577X gene polymorphism and low muscle mass or sarcopenia in older Turkish adults. The study included patients ≥65 years admitted to the geriatric outpatient clinic. Sarcopenia was diagnosed according to EWGSOP2 criteria. Blood samples were collected from the all participants, after DNA isolation, RT-PCR method was used for genotyping of polymorphisms. 197 participants were included aged between 65-99 years (mean age: 76,2±6,1 years old). 151 patients (76,6%) were female. XX genotype of ACTN3 was present in 23,9%. Homozygous (RR) and heterozygous (RX) genotypes were 31% and 45,2%, respectively. 50,8% had low SMMI(BMI). Alleles were not different between SMMI normal (RR 33%, RX 43%, XX 24%) and low groups (RR 29%, RX 47%, XX 24%)(p=0,81). 44.6% of the participants had probable sarcopenia, 29.4% had confirmed sarcopenia, and 19,2% had severe sarcopenia. In univariate analyses, there was no significant difference in ACTN3 polymorphism between older people with probable/confirmed/severe sarcopenia, and control group (the older people with normal muscle strength and mass). In regression analyses, neither low muscle mass nor sarcopenia was associated with ACTN3 R577X genotypes. In logistic regression analysis, high BMI having low muscle mass remained significant (OR=1.611; 95%CI=1.225-2.119, p=0.001) after the adjustment for covariates. Our study suggests that there is no significant relationship between muscle mass or sarcopenia and ACTN3 R577X gene polymorphism in Turkish older adults. Key Words: Sarcopenia, ACTN3, handgrip strength, SMMI, muscle mass