American Journal of Epidemiology Advance Access originally published online on March 27, 2009
American Journal of Epidemiology 2009 169(10):1267-1274; doi:10.1093/aje/kwp045
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ORIGINAL CONTRIBUTIONS |
Relation of Age-related Cataract With Obesity and Obesity Genes in an Asian Population
Correspondence to Dr. Tai E. Shyong, Department of Endocrinology, Singapore General Hospital, Outram Road, Singapore 169608 (e-mail: eshyong{at}pacific.net.sg).
Received for publication August 18, 2008. Accepted for publication January 30, 2009.
Obesity shows an inconsistent association with cataract. Causality has not been established. Polymorphisms at the fat mass- and obesity-associated (FTO) locus are associated with obesity and offer an opportunity to examine the obesity-cataract association using a mendelian randomization approach. The authors conducted a population-based study among Singaporean Malay adults (2004–2006) in which nuclear, cortical, and posterior subcapsular (PSC) cataracts were assessed and defined by slit-lamp examination using Lens Opacity Classification System III. Obesity was defined as body mass index (weight (kg)/height (m)2) 
30. The study included 3,000 subjects, of whom 1,339 (44.6%) had cataract (848 (28.3%) nuclear, 939 (31.3%) cortical, and 285 (9.5%) PSC). After multivariable adjustment for age, gender, diabetes, hypertension, smoking, and education, obesity was significantly associated with cortical (odds ratio (OR) = 1.31, 95% confidence interval (CI): 1.01, 1.71) and PSC (OR = 1.60, 95% CI: 1.10, 2.32) cataracts but not nuclear cataract. FTO single nucleotide polymorphisms known to be associated with obesity in this study population were not associated with cortical or PSC cataract but were associated with nuclear cataract (OR = 1.33, 95% CI: 1.11, 1.58), even in multivariate analyses controlling additionally for body mass index, diabetes, hypertension, and smoking (OR = 1.30, 95% CI: 1.08, 1.55). These results do not support a causal association between obesity and cortical or PSC cataract. The FTO gene may be involved in the pathogenesis of nuclear cataract.
cataract; obesity; polymorphism, single nucleotide
Abbreviations: CI, confidence interval; FTO, fat mass- and obesity-associated; LOCS III, Lens Opacity Classification System III; OR, odds ratio; PSC, posterior subcapsular; SD, standard deviation; SNP, single nucleotide polymorphism