title: Nuclear cataract shows significant familial aggregation in an older population after adjustment for possible shared environmental factors.
abstract: OBJECTIVE
  To quantify the association between siblings in age-related nuclear cataract, after adjusting for known environmental and personal risk factors.
  
  
  METHODS
  All participants (probands) in the Salisbury Eye Evaluation (SEE) project and their locally resident siblings underwent digital slit lamp photography and were administered a questionnaire to assess risk factors for cataract including: age, gender, lifetime sun exposure, smoking and diabetes history, and use of alcohol and medications such as estrogens and steroids. In addition, blood pressure, body mass index, and serum antioxidants were measured in all participants. Lens photographs were graded by trained observers masked to the subjects' identity, using the Wilmer Cataract Grading System. The odds ratio for siblings for affectedness with nuclear cataract and the sibling correlation of nuclear cataract grade, after adjusting for covariates, were estimated with generalized estimating equations.
  
  
  RESULTS
  Among 307 probands (mean age, 77.6 +/- 4.5 years) and 434 full siblings (mean age, 72.4 +/- 7.4 years), the average sibship size was 2.7 per family. After adjustment for covariates, the probability of development of nuclear cataract was significantly increased (odds ratio [OR] = 2.07, 95% confidence interval [CI], 1.30-3.30) among individuals with a sibling with nuclear cataract (nuclear grade > or = 3.0). The final fitted model indicated a magnitude of heritability for nuclear cataract of 35.6% (95% CI: 21.0%-50.3%) after adjustment for the covariates.
  
  
  CONCLUSIONS
  Findings in this study are consistent with a genetic effect for age-related nuclear cataract, a common and clinically significant form of lens opacity.
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
authors.forename: Nathan
authors.initials: N
authors.lastname: Congdon
authors.forename: Karl W
authors.initials: KW
authors.lastname: Broman
authors.forename: Hong
authors.initials: H
authors.lastname: Lai
authors.forename: Beatriz
authors.initials: B
authors.lastname: Munoz
authors.forename: Heidi
authors.initials: H
authors.lastname: Bowie
authors.forename: Donna
authors.initials: D
authors.lastname: Gilber
authors.forename: Robert
authors.initials: R
authors.lastname: Wojciechowski
authors.forename: Christine
authors.initials: C
authors.lastname: Alston
authors.forename: Sheila K
authors.initials: SK
authors.lastname: West
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002386:Cataract / Q000235:genetics* / Q000473:pathology; D004777:Environment; D005192:Family Health; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007907:Lens Nucleus, Crystalline / Q000473:pathology*; D008297:Male; D012307:Risk Factors; D035781:Siblings