Infantile cerebellar atrophy.

We describe a family whose members have a dominantly inherited, early-onset, nonprogressive syndrome that includes spontaneous upbeating nystagmus and mild gait ataxia. Magnetic resonance imaging showed localized atrophy of the cerebellar vermis. Several families described in the literature resemble our family but differ in mode of inheritance, age at onset, rate of progression, or clinical findings. We believe this family represents a unique type of inherited early-onset atrophy of the cerebellar vermis.