Hereditary retinoschisis linkage studies in a family and considerations in genetic counselling.

We report a family with X-linked juvenile retinoschisis. In addition to the three males with severe visual impairment, six other males in this family were found to have hitherto undiagnosed disease. The findings in these mildly affected males are described in detail. The wide range of clinical manifestations found among the affected relatives initially hampered recognition of the correct diagnosis. Once the correct diagnosis was made, proper genetic counselling could be given. The data are compatible with loose linkage between the loci for juvenile retinoschisis and the red cell antigen marker Xga.