X-linked juvenile retinoschisis: mutations at the retinoschisis and Norriedisease gene loci?

Juvenile retinoschisis (RS) and Norrie disease (ND) are X-linked recessive retinal disorders. Both disorders, in the majority of cases, are monogenic and are caused by mutations in the RS and ND genes, respectively. Here we r eport the identification of a family in which mutations in both the RS and ND genes are segregating with RS pathology. Although the mutations identifi ed in this report were not functionally characterized with regard to their pathogenicity, it is likely that both of them are involved in RS pathology in the family analyzed. This suggests the complexity and digenic nature of monogenic human disorders in some cases. If this proves to be a widespread problem, it will complicate the strategies used to identify the genes invol ved in diseases and to develop methods for intervention.