Mental retardation in amaurosis congenita of Leber.

A group of 229 patients with Leber's congenital amaurosis (ACL) was investigated for associated defects. We especially looked for the occurrence of mental retardation because the literature gives varying frequencies for this association. A percentage of 19.8% was found. This finding has consequences for genetic counseling. Special attention was given to how frequently sibling pairs occurred in which one patient was mentally retarded whereas the other functioned normally. We found 11 sibling pairs that were discordant with regard to their mental state. This observation proves that mental retardation could be one variable expression of ACL.