title: The ACTN3 R577X genotype is associated with muscle function in a Japanese population.
abstract: Homozygosity for the common nonsense polymorphism R577X in the α-actinin-3 gene (ACTN3) causes complete α-actinin-3 deficiency in fast-twitch skeletal muscle fibers. This study investigated whether the ACTN3 R577X polymorphism affects fitness status using a battery of tests in a large Japanese cohort. In the present study, 1227 subjects (age: 25-85 years) were genotyped for the ACTN3 R577X polymorphism (rs1815739) using a TaqMan SNP genotyping assay (Applied Biosystems). All subjects were divided into 2 groups based on their age (<55 years and ≥55 years). All subjects completed a questionnaire about exercise habits and were subjected to a battery of tests to assess their fitness status (including grip strength test, chair stand test, and 8-foot walking test). A significant association between the ACTN3 R577X genotype and chair stand test performance was observed in the group of men ≥55 using ANCOVA adjusted for age and exercise habits (p = 0.036). The ACTN3 R577X genotype accounted for 2.5% of the variability in the results of the chair stand test among men in the ≥55 age group. Moreover, for the ≥55 age group, performance in the chair stand test was lower among those with the XX genotype than among those with the RR genotype (p = 0.024) or RX genotype (p = 0.005), unlike results for the <55 age group. No significant difference was noted for hand grip strength or 8-foot walking time. Thus, our results suggest that the ACTN3 R577X genotype is associated with lower-extremity muscle function in the Japanese population.
authors.affiliation: Sports Training Center, Nippon Sport Science University, Tokyo, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Kikuchi
authors.forename: Shou
authors.initials: S
authors.lastname: Yoshida
authors.forename: Seok-ki
authors.initials: SK
authors.lastname: Min
authors.forename: Kihyuk
authors.initials: K
authors.lastname: Lee
authors.forename: Mikako
authors.initials: M
authors.lastname: Sakamaki-Sunaga
authors.forename: Takanobu
authors.initials: T
authors.lastname: Okamoto
authors.forename: Koichi
authors.initials: K
authors.lastname: Nakazato
mesh_terms: D000185:Actinin / Q000235:genetics* / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000235:genetics*; D015992:Body Mass Index; D018389:Codon, Nonsense; D015331:Cohort Studies; D015444:Exercise; D005260:Female; D017353:Gene Deletion; D018737:Hand Strength; D015438:Health Behavior; D006720:Homozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism*; D011110:Polymorphism, Genetic; D011795:Surveys and Questionnaires
chemical_list: C118456:ACTN3 protein, human; D018389:Codon, Nonsense; D000185:Actinin
keywords: aging; batterie de tests; fonction musculaire; force musculaire; muscle function; muscle strength; polymorphism; polymorphisme; test battery; vieillissement; α-actinin-3; α-actinine-3