A study of certain traits accompanying some inherted neurological disorders

Feeblemindedness, dementia, mental disorders, and epilepsy, as well as optic atrophy, tapeto-retinal degenerations, cataract, ophthalmoplegias, and neural hearing loss were found more frequently in patients suffering from hereditary ataxias (HA) and allied disorders than in the general population. Mental disorders and squints, and in certain instances also ocular myopathy, feeblemindedness, and cataract were found also in non-HA family members. These traits were particularly frequent in subjects with minor neurological signs previously defined as having an "unspecific neuropathy" (Un), and belonging to kindreds in which autosomal dominant HA segregated. Un clustering in such families is probably caused by other genetic (or other) mechanisms different from that governing the classical HA in the family. These presumably polygenic conditions are thought to be introduced into the HA kindreds by a negative selection. Optic atrophy, tapeto-retinal degenerations, surdity, epilepsy, and possibly also dementia, were found together with monomeric disease, as well as in the Un subjects, particularly in families with recessive HA. Such traits were equally rare in unaffected family members and controls. Un in such families as well as the traits mentioned may reflect manifestation of HA genes in heterozygotes. They could also reflect the presence of genes linked to the HA genes.