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.

Sacroiliitis in Systemic Lupus Erythematosus Revisited.

OBJECTIVES: This study aims to investigate the prevalence of inflammatory back pain (IBP) and sacroiliitis in a systemic lupus erythematosus (SLE) population as well as the association between IBP and the frequency of human leukocyte antigen B27 (HLA-B27). PATIENTS AND METHODS: The study included 281 SLE patients (16 males, 265 females; mean age 39.9±11.9 years; range, 20 to 69 years) and 100 healthy controls (HCs) (2 males, 98 females; mean age 41.2±10.1 years; range, 19 to 64 years). Participants were administered a five-item Assessment of SpondyloArthritis international Society-IBP questionnaire. Patients and controls with IBP underwent detailed clinical and laboratory examinations to detect sacroiliitis. Radiographic evaluations were performed by a blinded rheumatologist and radiologist. Interobserver reliability was assessed with Cohen's kappa test. RESULTS: According to the questionnaire, IBP was present in 46 SLE patients (46/281; 16.3%) whereas none of the HC had IBP (p<0.001). In radiological assessment, 22 SLE patients (7.8%) had sacroiliitis detected by conventional X-ray and/or magnetic resonance imaging. Only one SLE patient with sacroiliitis had HLA-B27. CONCLUSION: Our study showed that IBP is increased in SLE patients and IBP in SLE is not associated with HLA-B27.