title: Familial resemblance and shared latent familial variance in recurrent fall risk in older women.
abstract: BACKGROUND
  A possible familial component to fracture risk may be mediated through a genetic liability to fall recurrently.
  
  
  METHODS
  Our analysis sample included 186 female sibling-ships (n=401) of mean age 71.9 yr (SD=5.0). Using variance component models, we estimated residual upper-limit heritabilities in fall-risk mobility phenotypes (e.g., chair-stand time, rapid step-ups, and usual-paced walking speed) and in recurrent falls. We also estimated familial and environmental (unmeasured) correlations between pairs of fall-risk mobility phenotypes. All models were adjusted for age, height, body mass index, and medical and environmental factors.
  
  
  RESULTS
  Residual upper-limit heritabilities were all moderate (P<0.05), ranging from 0.27 for usual-paced walking speed to 0.58 for recurrent falls. A strong familial correlation between usual-paced walking speed and rapid step-ups of 0.65 (P<0.01) was identified. Familial correlations between usual-paced walking speed and chair-stand time (-0.02) and between chair-stand time and rapid step-ups (-0.27) were both nonsignificant (P>0.05). Environmental correlations ranged from 0.35 to 0.58 (absolute values), P<0.05 for all.
  
  
  CONCLUSIONS
  There exists moderate familial resemblance in fall-risk mobility phenotypes and recurrent falls among older female siblings, which we expect is primarily genetic given that adult siblings live separate lives. All fall-risk mobility phenotypes may be coinfluenced at least to a small degree by shared latent familial or environmental factors; however, up to approximately one-half of the covariation between usual-paced walking speed and rapid step-ups may be due to a common set of genes.
authors.affiliation: Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, 130 DeSoto St., A-551, Pittsburgh, PA 15261, USA. kimber.lilac@gmail.com
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Faulkner
authors.forename: Jane A
authors.initials: JA
authors.lastname: Cauley
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Roth
authors.forename: Candace
authors.initials: C
authors.lastname: Kammerer
authors.forename: Katie
authors.initials: K
authors.lastname: Stone
authors.forename: Teresa A
authors.initials: TA
authors.lastname: Hillier
authors.forename: Kristine E
authors.initials: KE
authors.lastname: Ensrud
authors.forename: Marc
authors.initials: M
authors.lastname: Hochberg
authors.forename: Michael C
authors.initials: MC
authors.lastname: Nevitt
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Zmuda
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control; D000368:Aged; D004777:Environment; D005260:Female; D050723:Fractures, Bone / Q000208:ethnology / Q000235:genetics* / Q000503:physiopathology / Q000517:prevention & control; D020022:Genetic Predisposition to Disease; D015577:Geriatric Assessment; D040941:Heredity; D006801:Humans; D015233:Models, Statistical; D009043:Motor Activity; D009141:Musculoskeletal System / Q000503:physiopathology*; D010375:Pedigree; D010641:Phenotype; D012008:Recurrence; D018570:Risk Assessment; D012307:Risk Factors; D035781:Siblings; D014481:United States / Q000453:epidemiology; D016138:Walking; D044465:White People / Q000235:genetics