Is there a relationship between ACTN3 R577X gene polymorphism and sarcopenia?

BACKGROUND AND AIMS: The alpha-actinin (ACTN) genes are important structural components of the sarcomere. Sarcopenia is a common geriatric syndrome characterized by morbidity and mortality. Our study aimed to examine the relationship between the ACTN3 R577X gene and sarcopenia in community-dwelling Turkish adults. METHODS: We designed a cross-sectional study among the patients aged ≥ 65 years admitted to the geriatric outpatient clinic. We recorded the general characteristics of the patients. We used the Jamar hand dynamometer to evaluate handgrip strength. Body composition was estimated using bioimpedance analysis. Sarcopenia was diagnosed according to the European Working Group on Sarcopenia in Older People2 criteria with population-specific cutoffs. We performed analyses of low muscle mass (LMM) with skeletal muscle mass index adjusted for body mass index [SMMI(BMI)]. We further categorized the SMMI(BMI) cutoffs into tenths. The analyzes were performed according to the 90th percentile SMMI(BMI) cutoffs. Peripheral blood samples were collected to determine the ACTN3 genotypes. RESULTS: 197 participants were included [mean age: 76.3 ± 6.1 years, 151 (76.6%) women]. The proportions of the ACTN3 genotypes were as follows: RX (45.1%) > RR (31%) > XX (23.9%). The significant difference between genotypes was found only for low SMMI(BMI) according to the 90th percentile (p = 0.025). In multivariate analysis, only gender (female) was independently associated with LMM. CONCLUSION: We did not find any association between ACTN3 R577X gene polymorphism and probable sarcopenia, confirmed sarcopenia and LMM. Besides, much more research is needed to reveal how ethnicity affects the muscles of older adults with ACTN3 R577X gene polymorphism.

The impact of platelet membrane glycoprotein Ib alpha and Ia/IIa polymorphisms on the risk of thrombosis in the antiphospholipid syndrome.

BACKGROUND: Pathogenesis of thrombus formation in antiphospholipid syndrome (APS) is not clear. Platelet membrane glycoprotein (GP) receptors play important roles in development of thrombosis. OBJECTIVES: We investigated the association between development of thrombosis in APS and polymorphisms of GPIb alpha variable number of tandem repeats (VNTR), Kozak, and GPIa C807T. Patients/Methods Sixty patients with APS (30 with proven thrombosis and 30 without thrombosis) and 63 controls were included. Presence of GPIa C807T polymorphism was determined with real-time PCR and GPIb alpha Kozak and VNTR polymorphisms by conventional PCR. RESULTS: Frequency of C807T TT genotype was significantly higher in APS with thrombosis than APS without thrombosis (p=0.023) and also in APS with multiple thrombi compared to APS without thrombi (p=0.023). Frequency of Kozak TC genotype was higher in APS with arterial thrombosis compared to APS with venous thrombosis, controls, and APS without thrombosis (p=0.03, p=0.0007, and p=0.0024 respectively). D allele frequency and D allele carrier state for VNTR were significantly less in APS than controls (p=0.0018 and p=0.0046 respectively). CONCLUSIONS: C807T TT genotype may confer a risk for thrombosis and Kozak TC genotype for arterial thrombosis. D allele of VNTR may protect from APS. No patients with C807T TT or Kozak TC genotypes carried the protective DD genotype of VNTR. These polymorphisms may increase risk for both arterial and venous thrombosis. The utility of prophylaxis with anti-platelet drugs in at least a subgroup of APS patients should be investigated with clinical trials.