Linkage analysis in a family with complete type congenital stationary night blindness with and without myopia.

A family is described with X-linked congenital stationary night blindness of the complete type (CSNB1) in which clinical variation between affected males resulted in diagnostic difficulties. In two affected male cousins, one had congenital nystagmus and myopia, while the other was initially thought to have retinitis pigmentosa with optic atrophy and was hyperopic. The diagnosis of X-linked congenital stationary night blindness was established by clinical, psychophysical and electrophysiological criteria, and DNA markers flanking the CSNB1 locus were analysed in the family. The results show that both affected males have inherited the same haplotype from their carrier mothers, excluding the possibility that a myopia gene in linkage disequilibrium with CSNB1 has recombined with this locus.