Nuclear cataract shows significant familial aggregation in an older population after adjustment for possible shared environmental factors.
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.
Congdon
Nathan
N
Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
Broman
Karl W
KW
Lai
Hong
H
Munoz
Beatriz
B
Bowie
Heidi
H
Gilber
Donna
D
Wojciechowski
Robert
R
Alston
Christine
C
West
Sheila K
SK
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