title: Polymorphic variation in the human myostatin (GDF-8) gene and association with strength measures in the Women's Health and Aging Study II cohort.
abstract: OBJECTIVE
  To determine whether polymorphic variation in the myostatin gene differentially influences the maintenance of muscle strength in older adults, and to find supportive evidence in a cohort of older women.
  
  
  METHODS
  Correlation study of polymorphic variation in a cohort of older women.
  
  
  METHODS
  Representatively sampled older female population living in the eastern half of Baltimore, Maryland.
  
  
  METHODS
  Participants were 286 women, age 70 to 79. Of these, 81.1% were Caucasian, 18.8% were African American, and 0.2% were Asian or Hispanic.
  
  
  METHODS
  Overall strength was measured with a dynamometer and defined as the sum of the strongest measures of hip, knee, and grip strength on the dominant side.
  
  
  RESULTS
  We identified or confirmed six myostatin polymorphic variants in the Women's Health and Aging Study II population. Of the polymorphisms, K153R is the most common, with an allele frequency of 0.19 in African Americans. Unadjusted mean strength by genotype suggested lower muscle strength in those African-American women with the R genotype compared with those with the K genotype (K/K: 72.50 +/- 13.9 kg (n = 39) vs K/R: 67.14 +/- 11.4 kg (n = 13) vs R/R: 63.1 +/- 11.3 kg (n = 3)). After adjustment for race in a linear regression model, the R genotype remained associated with lower strength levels (P = .04). Statistical significance decreased when body mass index and race were both added to the model (P = .09).
  
  
  CONCLUSIONS
  Recognizing that small sample size in the study of genes of modest effect are unlikely to yield significant differences, these data suggest an association of the R153 allele with lower strength in high-functioning older women, which should be studied further in a larger cohort.
authors.affiliation: Johns Hopkins University School of Medicine, Department of Medicine, Division of Geriatric Medicine and Gerontology, Baltimore, Maryland, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Seibert
authors.forename: Q L
authors.initials: QL
authors.lastname: Xue
authors.forename: L P
authors.initials: LP
authors.lastname: Fried
authors.forename: J D
authors.initials: JD
authors.lastname: Walston
mesh_terms: D000368:Aged; D015142:Baltimore / Q000453:epidemiology; D044383:Black People / Q000235:genetics; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000453:epidemiology; D006801:Humans; D016014:Linear Models; D018482:Muscle, Skeletal / Q000502:physiology*; D009133:Muscular Atrophy / Q000453:epidemiology / Q000235:genetics*; D055435:Myostatin; D018807:Polymorphism, Single-Stranded Conformational; D016212:Transforming Growth Factor beta / Q000235:genetics*; D044465:White People / Q000235:genetics; D001741:Black or African American
chemical_list: C525911:MSTN protein, human; D055435:Myostatin; D016212:Transforming Growth Factor beta