PURPOSE:

High myopia is a common genetic variant that severely affects vision. Genes responsible for myopia without linked additional functional defects have not been identified. Mutations in the nyctalopin gene (NYX) located at Xp11.4 are responsible for a complete form of congenital stationary night blindness (CSNB1). High myopia is usually observed in patients with CSNB1. This study was designed to test the possibility that mutations in the NYX gene might cause high myopia without congenital stationary night blindness (CSNB).

METHODS:

The genomic sequence of NYX in 52 male probands with high myopia but without CSNB was analyzed through direct DNA sequencing. Variations in the NYX were verified by analyzing available family members and 232 controls.

RESULTS:

Two unrelated male individuals with high myopia but without night blindness were found to have novel Cys48Trp and Arg191Gln mutations in NYX. The mutations were found to be located in distinct regions, different from the locations of mutations known to cause congenital stationary night blindness with myopia (CSNB1).

CONCLUSIONS:

Mutations in NYX may cause high myopia without CSNB. The observations suggest that NYX may have independent effects on myopia and night blindness.