title: Genetic and environmental contributions to strabismus and phoria: evidence from twins.
abstract: The causes of manifest (strabismus) and latent (phoria) misalignment of the visual axes are incompletely understood. We calculated genetic and environmental contributions to strabismus based upon a critical review and quantitative meta-analysis of previous strabismus twin studies (n=3418 twin pairs) and calculated contributions to phoria based upon a new twin study (n=307 twin pairs). Our results suggest that genetic liability is necessary to develop strabismus, whereas environmental factors are sufficient to cause most phorias. The different etiologies implied by this work suggest that strabismus and phoria should be carefully distinguished in epidemiological work.
authors.affiliation: Wellesley College, Psychology, Wellesley, MA 02481, USA. jwilmer@wellesley.edu
authors.forename: Jeremy B
authors.initials: JB
authors.lastname: Wilmer
authors.forename: Benjamin T
authors.initials: BT
authors.lastname: Backus
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004200:Diseases in Twins / Q000209:etiology* / Q000235:genetics; D019317:Evidence-Based Medicine / Q000379:methods; D020022:Genetic Predisposition to Disease; D006801:Humans; D015201:Meta-Analysis as Topic; D012307:Risk Factors; D013285:Strabismus / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics; D018433:Twin Studies as Topic / Q000379:methods; D055815:Young Adult
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