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Matthew P Johnson, Suman S Thapa, Kent L Anderson, Mohan K Shrestha, Sandra Laston, Bradford Towne, Janardan Subedi, John Blangero, Sarah Williams-blangero; Characterizing the genetic architecture of ocular biometrics in a south Asian population: The Jiri Eye Study. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4840.
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© ARVO (1962-2015); The Authors (2016-present)
Approximately 90% (n=660 million) of the world’s visually impaired reside in developing countries. Combatting ocular-related health problems in these countries is critical if we are to reduce the global burden associated with visual impairment (VI). The objective of a study recently established in eastern Nepal is to characterize the genetic architecture of ocular-trait measures known to influence VI prevalence. Nepal is a developing country where the prevalence of VI across regions ranges from 7% to 42%.
Our family-based study design involves recruitment of 2,000 members of the Jirel population, a small endogamous ethnic group from the Jiri region of Nepal. Participants undergo a comprehensive eye examination to document ocular biometrics such as central corneal thickness (CCT) and intraocular pressure (IOP), known risk factors for glaucoma. A variance components method is employed to determine the underlying genetic architecture (heritability, pleiotropy) of all measured ocular-related traits (e.g., CCT, IOP) and disease end-points (e.g., glaucoma). The Jirel participants belong to a single extended pedigree containing >62,000 pair-wise relationships that are informative for genetic analysis. The Jirel pedigree has 80% power to detect an additive genetic heritability as low as 6.5% and a genetic correlation between two traits as low as 4.4%.
Our first data collection session yielded the recruitment of 229 members of the Jirel population to the study. Their mean (range) age at exam was 45.7 (13-85) years. Mean (median) CCT values: OD 530.6 (534.0) µm, OS 528.8 (536.5) µm. Mean (median) IOP values: OD 14.2 (14.0) mmHg, OS 14.2 (14.0) mmHg. We have recently completed our second data collection session and have recruited an additional 308 members of the Jirel population to the study. By our third data collection session (April 2016) we anticipate a total of approximately 850 Jirels to be recruited to the study, allowing us to then determine initial heritability and plieotropy estimates to explain the basic underlying genetic architecture of these clinically important ocular measures.
Evaluating the genetic architecture of ocular biometry, especially in under-studied populations from the developing world, may yield new information on the biological pathways underlying VI, and thus may be an important step to help address global burden associated with VI.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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