An autosomal recessive cerebellar ataxia that is characterized by the onset of ataxia between age three and thirty including axonal sensorimotor neuropathy, cerebellar atrophy and elevated alpha-fetoprotein that has_material_basis_in homozygous or compound heterozygous mutation in the SETX gene on chromosome 9q34.13. Oculomotor apraxia is common, but not universal.