Two sisters with mental retardation, cataract, ataxia, progressive hearing loss, and polyneuropathy

Two sisters are described with a disorder characterised by mental retardation, congenital cataract, progressive spinocerebellar ataxia, sensorineural deafness, and signs of peripheral neuropathy. Progressive hearing loss, ataxia, and polyneuropathy became evident in the third decade. The differential diagnosis of this syndrome is discussed including the syndromes described by Berman et al and Koletzko et al.