Exploring Factors Underlying Ethnic Difference in Age-related Macular Degeneration Prevalence

ABSTRACT

Aims

To assess contributions of dietary and genetic factors to ethnic differences in AMD prevalence.

Design

Population-based analytical study.

Methods

In the Blue Mountains Eye Study, Australia (European ancestry n = 2826) and Multi-Ethnic Cohort Study, Singapore (Asian ancestry, n = 1900), AMD was assessed from retinal photographs. Patterns of dietary composition and scores of the Alternative Healthy Eating Index were computed using food frequency questionnaire data. Genetic susceptibility to AMD was determined using either single nucleotide polymorphisms (SNPs) of the complement factor H and age-related maculopathy susceptibility 2 genes, or combined odds-weighted genetic risk scores of 24 AMD-associated SNPs. Associations of AMD with ethnicity, diet, and genetics were assessed using logistic regression. Six potential mediators covering genetic, diet and lifestyle factors were assessed for their contributions to AMD risk difference between the two samples using mediation analyses.

Results

Age-standardized prevalence of any (early or late) AMD was higher in the European (16%) compared to Asian samples (9%, p < .01). Mean AMD-related genetic risk scores were also higher in European (33.3 ± 4.4) than Asian (Chinese) samples (31.7 ± 3.7, p < .001). In a model simultaneously adjusting for age, ethnicity, genetic susceptibility and Alternative Healthy Eating Index scores, only age and genetic susceptibility were significantly associated with AMD. Genetic risk scores contributed 19% of AMD risk difference between the two samples while intake of polyunsaturated fatty acids contributed 7.2%.

Conclusion

Genetic susceptibility to AMD was higher in European compared to Chinese samples and explained more of the AMD risk difference between the two samples than the dietary factors investigated.

KEYWORDS:

• Epidemiology
• age-related macular degeneration
• ethnic difference
• diet
• genetic risk

Conflicts of Interest

None of the authors has any conflicts of interest to disclose, nor any financial disclosure to make.

Additional information

Funding

National Health & Medical Research Council, Australia: Project grant [ID 590204]. The sponsor or funding organization had no role in the design or conduct of this research.