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Automated discovery and quantification of image-based complex phenotypes: a twin study of drusen phenotypes in age-related macular degeneration
Journal article   Open access   Peer reviewed

Automated discovery and quantification of image-based complex phenotypes: a twin study of drusen phenotypes in age-related macular degeneration

Gwenole Quellec, Stephen R Russell, Johanna M Seddon, Robyn Reynolds, Todd Scheetz, Vinit B Mahajan, Edwin M Stone and Michael D Abràmoff
Investigative ophthalmology & visual science, Vol.52(12), pp.9195-9206
11/25/2011
DOI: 10.1167/iovs.10-6793
PMCID: PMC3302481
PMID: 22039249
url
https://doi.org/10.1167/iovs.10-6793View
Published (Version of record) Open Access

Abstract

Determining the relationships between phenotype and genotype of many disorders can improve clinical diagnoses, identify disease mechanisms, and enhance therapy. Most genetic disorders result from interaction of many genes that obscure the discovery of such relationships. The hypothesis for this study was that image analysis has the potential to enable formalized discovery of new visible phenotypes. It was tested in twins affected with age-related macular degeneration (AMD). Fundus images from 43 monozygotic (MZ) and 32 dizygotic (DZ) twin pairs with AMD were examined. First, soft and hard drusen were segmented. Then newly defined phenotypes were identified by using drusen distribution statistics that significantly separate MZ from DZ twins. The ACE model was used to identify the contributions of additive genetic (A), common environmental (C), and nonshared environmental (E) effects on drusen distribution phenotypes. Four drusen distribution characteristics significantly separated MZ from DZ twin pairs. One encoded the quantity, and the remaining three encoded the spatial distribution of drusen, achieving a zygosity prediction accuracy of 76%, 74%, 68%, and 68%. Three of the four phenotypes had a 55% to 77% genetic effect in an AE model, and the fourth phenotype showed a nonshared environmental effect (E model). Computational discovery of genetically determined features can reveal quantifiable AMD phenotypes that are genetically determined without explicitly linking them to specific genes. In addition, it can identify phenotypes that appear to result predominantly from environmental exposure. The approach is rapid and unbiased, suitable for large datasets, and can be used to reveal unknown phenotype-genotype relationships.
Phenotype Registries Genetic Predisposition to Disease Retinal Drusen - genetics Diseases in Twins - genetics Twins, Monozygotic - genetics Humans Genotype Male Macular Degeneration - diagnosis Twins, Dizygotic - genetics Retinal Drusen - diagnosis Macular Degeneration - genetics Aged, 80 and over Female

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