Nonprogressive cerebellar disorder with mental retardation and autosomal recessive inheritance in Hutterites.

We report a nonprogressive neurological disorder in at least 11 Hutterites with healthy but consanguineous parents. In several of the affected, hypotonia was noted at birth. Retarded motor and mental development became apparent during the first year of life. The age of unsupported walking varied from 5-21 years. Consistent signs were unsteady, broadly based gait and stance, exaggerated deep tendon reflexes mainly in the lower limbs, and mild to moderate mental retardation. Variable signs were extensor plantar reflexes (9/11), short stature (-2SD in 8/11), strabismus (7/11), small muscle mass (6/11), mild intention tremor (3/11), cataracts (1/11), and epilepsy (1/11). CAT scans in two affected sisters showed slight enlargement of the fourth ventricle in one and hypoplasia of the cerebellum in both. The disorder is probably the same as that described earlier under the heading, dysequilibrium syndrome.