Background: This study aimed to assess heritability of myopia in Lithuania and evaluate both genes GJD2 (Gap Junction Protein, Delta 2) and RASGRF1 (RAS protein-specific guanine nucleotide-releasing factor 1) relation with myopia.
Methods: In this study Lithuanian twin population aged between 18 and 40 (n = 460) were examined. Single-nucleotide polymorphisms of the RASGRF1 (rs8027411) and GJD2 (rs634990) genes were assessed by real-time polymerase chain reaction method.
Results: Intrapair correlations for spherical equivalent in all twin pairs were significantly higher in MZ twin pairs r = 0.539 (p < 0.001, 95% CI 0.353-0.684) than in DZ twin pairs r = 0.203 (p < 0.01, 95% CI 0.0633-0.442) in myopia group. Correlations for spherical equivalent in emmetropia group were not significant in MZ twin pairs r = 0.091 (p > 0.05, 95% CI -0.215-0.381) and in DZ twin pairs r = - 0.220 (p > 0.05, 95% CI -0.587-0.222). The odds ratio (95% CI) were 2.7 (1.018-7.460) for combinations of genotypes of rs634990 CC and rs8027411 GT (p = 0.046).
Conclusions: Our studies have shown that the heritability of myopia makes 67.2% in Lithuania. Persons with combinations of genotypes rs634990 CC and rs8027411 GT have 2.7 times higher odds to have myopia.
Keywords: GJD2; Myopia; RASGRF1; Twin.