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Matthew P Johnson, Suman Thapa, Sandra Laston, Kent L Anderson, Mohan Shrestha, Bradford Towne, Janardan Subedi, John Blangero, Sarah Williams-Blangero; Genetic analysis of glaucoma endophenotypes in a large Nepalese extended pedigree: The Jiri Eye Study.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2133. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The objective of this project is to investigate the genetic epidemiology of ocular health and disease in a minority population from Nepal, a developing country. For this element of our project we are interested in the trait distribution and genetic architecture of known glaucoma endophenotypes: intraocular pressure (IOP), central corneal thickness (CCT) and vertical cup-to-disc ratio (CDR).
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 that includes measurements of IOP by Goldmann applanation tonometry, CCT by optical coherence tomography, and CDR by slit lamp ophthalmoscopy. We use a variance components method (SOLAR) to determine the underlying genetic architecture (e.g., heritability) of these glaucoma endopheotypes.
The Jirel participants belong to a single extended pedigree containing more than 62,000 pair-wise relationships that are informative for genetic analysis. To date, 790 members (459 female, 331 male) of the Jirel population have been recruited to the study. The mean (SD, range) age at exam is 42.6 (17.0, 18-88) years. The prevalance of open angle and angle closure glaucoma is 2.6% and 0.8%, respectively. The mean (SD) of IOP (maximum of both eyes), CCT (average of both eyes) and CDR (maximum of both eyes) is 14.7 (2.6) mm Hg, 521.7 (38.9) µm, and 0.3 (0.2), respectively. IOP (h2 = 0.28, p = 1.9E-04), CCT (h2 = 0.67, p = 1.5E-19), and CDR (h2 = 0.59, p = 4.3E-15) are all significantly heritable in the Jirel population.
Evaluating the genetic architecture of glaucoma endophenotypes, especially in under-studied populations from the developing world, will yield new information on the biological pathways underlying these traits, and thus may be an important step towards ultimately alleviating the global burden of glaucoma-associated visual impairment.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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