Myopia, or nearsightedness, is a refractive error of the eye. Light rays from a distant object are focused in front of the retina and those from a near object are focused in the retina; therefore distant objects are ... Myopia, or nearsightedness, is a refractive error of the eye. Light rays from a distant object are focused in front of the retina and those from a near object are focused in the retina; therefore distant objects are blurry and near objects are clear (summary by Kaiser et al., 2004). - Genetic Heterogeneity of Susceptibility to Myopia MYP2 maps to chromosome 18p. Other myopia loci include MYP1 (310460) on Xq28; MYP3 (603221) on 12q; MYP5 (608474) on 17q; MYP6 (608908) on 22q12; MYP7 (609256) on 11p13; MYP8 (609257) on 3q26; MYP9 (609258) on 4q12; MYP10 (609259) on 8p23; MYP11 (609994) on 4q22-q27; MYP12 (609995) on 2q37.1; MYP13 (300613) on Xq23-q25; MYP14 (610320) on 1p36; MYP15 (612717) on 10q21.1; MYP16 (612554) on 5p15.33-p15.2; MYP17 (formerly MYP4) (608367) on 7p15; MYP18 (255500) on chromosome 14q21-q24; MYP19 (613969) on 5p15.1-p13.3; MYP20 (614166) on 13q12.12; MYP21 (614167), caused by mutation in the ZNF644 gene (614159) on 1p22.2; MYP22 (615420), caused by mutation in the CCDC111 gene (615421) on 4q35; and MYP23 (615431), caused by mutation in the LRPAP1 gene (104225) on 4p16.
Myopia is, in a sense, a metric character. Variation in many components of the eye contributes to its refractive capacity (Sorsby et al., 1962). High-grade myopia is a refractive error greater than or equal to -6.00 diopters (Young ... Myopia is, in a sense, a metric character. Variation in many components of the eye contributes to its refractive capacity (Sorsby et al., 1962). High-grade myopia is a refractive error greater than or equal to -6.00 diopters (Young et al., 1998). Young et al. (1998) studied 8 medium to large multigenerational families with an autosomal dominant pattern of myopia of more than -6.00 diopters. Myopic individuals had no clinical evidence of connective tissue abnormalities, and the average age at diagnosis of myopia was 6.8 years. The average spherical component refractive error for the affected individuals was -9.48 diopters.
Lam et al. (2003) investigated the coding exons of TGF-beta-induced factor (TGIF; 602630), which maps to chromosome 18p, for mutations in Chinese patients with high myopia. Six SNPs showed a significant difference (P less than 0.05) between patient ... Lam et al. (2003) investigated the coding exons of TGF-beta-induced factor (TGIF; 602630), which maps to chromosome 18p, for mutations in Chinese patients with high myopia. Six SNPs showed a significant difference (P less than 0.05) between patient and control subjects in univariate analysis. Only 657T-G showed statistical significance in the logistic regression model (odds ratio 0.133; 95% CI 0.036-0.488; P = 0.002). Lam et al. (2003) concluded that TGIF is a probable candidate gene for high myopia. - Reviews See Young (2009) for a review of myopia.