Complete congenital stationary night blindness maps on Xp11.4 in a Sardinian family

X-linked congenital stationary night blindness (CSNBX) is a hereditary non-progressive retinal disorder, which can appear in two different clinical forms, complete and incomplete, associated with CSNB1 and CSNB2 loci on Xp. We describe a Sardinian family with complete CSNBX and define better the limits of the CSNB1 genetic locus on Xp11.4 through linkage analysis. Haplotype analysis showed two key recombinants, which restrict the CSNB1 locus to a region of about 3 cM limited by markers DSX1068 and DSX6810 respectively. The locus that we describe is included in the CSNB1 locus defined by previous reports referring to the same clinical form of the disease. These results, in addition to other recent mapping reports about families from different geographical areas, confirm the genetic homogeneity of X-linked complete CSNB.