Mapping of locus for X-linked congenital stationary night blindness (CSNB1) proximal to DXS7.

A recombinant chromosome in a male affected with X-linked congenital stationary night blindness (CSNB1) provides new information on the location of the CSNB1 locus. A four-generation family with five males affected with X-linked CSNB was analyzed with five polymorphic markers for four X-chromosome loci spanning the region OTC (Xp21.1) to DXS255 (Xp11.22). Four of the males inherited the same X chromosome; one male inherited a chromosome that from OTC to DXS7, inclusive, was derived from the normal X chromosome of his unaffected grandfather and that from a location between DXS7 and DXS426 proximally was derived from the chromosome carrying the CSNB1 locus. This recombinant maps the CSNB1 locus in this family to a region on the short arm of the X chromosome proximal to the DXS7 locus.