Localization of a novel X-linked congenital stationary night blindness locus: close linkage to the RP3 type retinitis pigmentosa gene region.

X-linked congenital stationary night blindness (CSNBX) is a non-progressive retinal disorder characterized by decreased visual acuity and loss of night vision. CSNBX is clinically heterogeneous with respect to the involvement of retinal rods and/or cones in the disease. In this study, we localize a new locus for CSNBX to Xp21.1, thus providing evidence that CSNBX is also genetically heterogeneous. A clear correlation between different genotypes and phenotypes cannot be found yet. The new CSNBX gene described here is closely linked to the X-linked retinitis pigmentosa type 3 gene region, which supports the hypothesis that there may be a functional relationship between congenital stationary night blindness and retinitis pigmentosa.