Abstract
Purpose: :
Myopia is the most common of all ocular conditions. The etiology of myopia is not known, both genetic and environmental factors seem to play a role. In high myopia, genetic factors appear to play a predominant role. The purpose of this study is to examine previously proposed familial high myopia loci as a first step before embarking on a genome–wide screen aimed at mapping and cloning gene(s) responsible for high myopia in Polish families.
Methods: :
To date, we have carefully examined, collected blood and purified DNA from 160 individuals with high myopia (<–6 diopters) from 28 unrelated families in Poland. The preliminary genotyping was conducted in 23 families. Prior to preceding with the targeting genotyping, linkage to markers for the myopic genetic syndromes of Stickler syndrome types I, II and III; Marfan syndrome and juvenile glaucoma were tested. Next, preliminary genotyping of high myopia associated loci [7q36 (MYP4), 12q21–23 (MYP3),18p11.31 (MYP2), and 17q21–23 (MYP5)] and MYP6 locus [mild/moderate myopia, 22q12] was performed.
Results: :
In Polish population familial high myopia seems to segregate in an autosomal dominant fashion. In order to evaluate whether there is sufficient power to detect linkage in the pedigrees, simulation studies were performed and revealed that the families have sufficient power to establish linkage that may lead to the identification of familial high myopia gene(s). Linkage to Stickler syndrome, Marfan syndrome and juvenile glaucoma loci were excluded. Genotyping with well–spaced polymorphic markers of high myopia associated loci is in progress.
Conclusions: :
We have identified, collected and characterized a large cohort of Polish families with high myopia and excluded the principal genetic cause of this phenotype. These families will be instrumental in identifying one or more locus for genetic high myopia.
Keywords: myopia • gene mapping • genetics