A family with fragile-X syndrome.

A family with fragile-X syndrome is reported. One sibling has atypical pervasive developmental disorder and moderate mental retardation. A second sibling has Tourette's syndrome, moderate mental retardation, seizure disorder, and autism. A third sibling has attention deficit disorder, moderate mental retardation, and developmental language disorder, expressive type. The authors believe that this family represents a classic example of the differential outcome of interactions of common biogenetic and environmental influences. We propose that in this family the multipotential outcome is at least influenced by if not caused by a common genetic defect.