Deletion mapping of a retinal cone‐rod dystrophy: Assignment to 18q211

Deletion of 18q211 was observed in a mentally retarded young man with electrophysiologically demonstrated cone-rod dystrophy, present since childhood. He had hypogonadism and a central postsynaptic hearing impairment. This is the first case of a chromosome deletion in a patient with a cone-rod dystrophy. Three patients with more distal deletions on chromosome 18 did not present retinal dystrophies. We suggest that one of the loci for cone-rod dystrophy may be located on chromosome 18 at q211-213. Reports of similar findings will be necessary for confirmation of this assumption.