The Heritability of Ocular Traits

Heritability is the proportion of phenotypic variation in a population that is attributable to genetic variation. among individuals. Many ophthalmic disorders and biometric traits are known to have a genetic basis and consequently much work has been published in the literature estimating the heritability of various ocular parameters. We collated and summarized the findings of heritability studies conducted in the field of ophthatmology. We grouped the various Studies broadly by phenotype as follows refract primary open-angle glaucoma, age-related macular degeneration (AMD), cataract, diabetic retinopathy, and others A total of 82 articles were retrieved from the literature relating to estimation of heritability loran ocular disease or biometric trait; of these, 37 papers were concerned with glaucoma, 28 with refraction, 4 with AM D, 5 with diabetic reunopathy, and 4 with cataract. The highest reported heritability for an ophthalmic trait is 0.99 for the phenotype >= 20 small hard, drusen, indicating that observed variation in this parameter is largely governed by genetic factors. Over 60% of the studies employed a twin study design and a similar percentage utilized variance components methods and structural equation modeling (SEM) to derive their heritability values. Using modern SEM techniques, heritability estimates derived from twin subjects were generally higher than those from family data. Many oldie estimates are in the moderate to high range, but to date the majority of genetic variants accounting for these findings have not been uncovered, hence in much work remains to be undertaken to elucidate fully their molecular etiology. (Surv Ophthalmol 55:561-583,2010. (c) 2010 Elsevier Inc All rights reserved)