Infantile-Onset Spinocerebellar Ataxia

Infantile-onset spinocerebellar ataxia (IOSCA) is a rare, recessively inherited condition recognized in a single kindred in Finland. These patients develop clumsiness and lose their ability to walk between 1 and 2 years of age. By school age, they develop ophthalmoplegia and loss of hearing. They develop sensory neuropathy by adolescence. Neurological examination reveals ataxia, athetosis, and muscle hypotonia with loss of deep tendon reflexes. Unlike FRDA, magnetic resonance imaging reveals cerebellar atrophy. Sensory nerve action potentials are markedly diminished in amplitude. Female patients have hypergonadotrophic hypogonadism. The gene responsible for IOSCA.