Refractive errors are continuous traits with a wide range in most populations. This suggests that many developmental and heritable (and perhaps environmental) components are responsible. No specific mutation has been identified but a number of 'susceptibility' loci have been mapped.
Myopia 2 has been linked to a susceptibility locus at 18q11.31.
Evidence of heritability in both syndromal and isolated myopia comes from several sources. For example, high myopia is a common feature in familial collagenopathies such as Marfan syndrome (154700), Kniest dysplasia (156550), and Stickler syndrome (108300). Multigenerational families with isolated myopia have been reported as well and mutations in multiple genes (at least 18) have been associated with these. Heredibility studies using twin pairs have identified additional mutations (609256). Further, the prevalence of myopia among children increases in the presence of parental myopia.
The transmission pattern in most families to which susceptibility loci have been linked is autosomal dominant. However, a susceptibility locus has been mapped to 14q22.1-q24.2 in several families with good evidence for autosomal recessive inheritance (255500). In addition, two loci on the X chromosome have been linked to presumed X-linked myopia (MYP1 [310460] at Xq28 and MYP13 [300613] at Xq23-q25). A patient with high myopia has been reported with a mutation in the NYX gene on the X-chromosome. This patient did not have congenital stationary night blindness of the type CSNB1A (310500) in which NYX is usually mutated.
