[Clinical features and genetic analysis in a family with X-linked incomplete congenital stationary night blindness (CSNBi)]. / Particularités cliniques et analyse génétique dans une famille atteinte de cécité nocturne non progressive congénitale héréditaire liée au chromosome X dans sa forme incomplète (CSNBi).

ABSTRACT

PURPOSE: We describe particular clinical features in a three-generation family with X-linked CSNBi and present the genetic analysis. METHOD: The diagnosis of CSNBi was established on clinical and electrophysiological criteria. Polymorphic DNA markers of the Xp region were analyzed by fluorescent polymerase chain reaction. RESULTS: Clinical findings evidenced an atypical association of both myopia and hyperopia in the same brotherhood. The most interesting feature in this family was the observation of major worsening of the clinical shape between the first and the third generation of affected individuals. DNA analysis did not show significant linkage between the disease and markers of the Xp11-p21 region. Southern analysis did not show expansion of trinucleotide repeat CAG/CTG and CCG/CGG over the three generation. CONCLUSION: Haplotypic analysis together with clinical observations allow to exclude the existence of a myopia gene closely linked to the CSNB2 locus. The clinical anticipation observed in this family does not seem to be linked with trinucleotide repeat expansion CAG/CTG or CCG/CGG.