Intronic Variants of TGIF1 (Variant-008) have a Potential to Associate with High Myopia in Ethnic Kashmiri Population

Myopia is the most common eye disorder which remains a significant ocular health problem associated with increased risk of visual loss around the world (Fredrick, 2002) . High myopia considered as more advanced type of myopia may lead to degenerative changes in the eye (degenerative myopia) leading to blindness and often afflicts, people earlier in life when they may still be active professionally (Jacobia et al., 2005). The wide spectrum of myopia-associated disorders strongly argues for an etiologically heterogeneous nature of myopic refractive errors, where multiple factors with genetic and epigenetic effects contribute at different stages during development (Feldkamper and Schaeffel, 2003). The concept that environmental factors influence ocular development has been well established in epidemiological and experimental animal studies (Saw et al., 2002). Despite recognized importance of visual experience in the development of myopia there is abundant evidence for genetic factors determining refractive development (Francois, 1961). First, higher myopia prevalence in developed Asian countries compared to the western world suggests a genetic susceptibility to myopia development. Further, myopic parents are more likely to give rise to offsprings with myopia than non-myopic parents (Goldschmidt, 1981). Linkage studies have mapped at least eight loci (MYP1, MYP2, MYP3, MYP4, MYP5, MYP11, MYP12 and MYP13) responsible for high myopia with Mendelian inheritance (Young, 2004). TGIF1 is expressed in sclera, retina, cornea, and optic nerve and competitively inhibits binding of the retinoic acid receptor to a retinoidresponsive promoter (Young et al., 1998a).