Purpose: We aimed to evaluate whether there is a relationship between ACTN3 R577X gene polymorphism and low muscle mass or sarcopenia in older Turkish adults.
Methods: The study included patients [ 65 years admitted to the geriatric outpatient clinic. Muscle mass was assessed with bioimpe- dance analysis (BIA). Muscle strength was evaluated by hand grip strength with a Jamar hydraulic hand dynamometer. Sarcopenia was diagnosed according to EWGSOP2 criteria. Skeletal muscle mass index (SMMI) was adjusted with two alternative methods: SMMI (height) and SMMI(BMI).

Results: 197 participants were included aged between 65 and 99 years (76.2±6,1 years old). 151 patients (76.6%) were female. RR, RX and XX genotype of ACTN3 were present in 31%, 45.2%, and 23.9%, respectively. No significant difference was observed in mean age, height, weight, body mass index, timed-up-and-go-test, chair stand, gait speed across the genotypes. 50.8% had low SMMI (BMI), whereas all participants except one case had normal SMMI (height). Alleles were not different between SMMI normal and low groups (p=0.81). 44.6% of the participants had probable sarcopenia, 29.4% had confirmed sarcopenia, and 19.2% had severe sarcopenia. In uni- variate analyses, there was no significant difference in ACTN3 polymorphism between older people with probable/confirmed/severe sarcopenia, and control group. In regression analyses, neither low muscle mass nor sarcopenia was associated with ACTN3 R577X genotypes.

Conclusion: Our study suggests that there is no significant relation- ship between muscle mass or sarcopenia parameters and ACTN3 R577X gene polymorphism in community dwelling older adults in Turkey.