Ataxia with oculomotor apraxia 2 (AOA-2) and amyotrophic lateral sclerosis (ALS4) are neurological disorders caused by mutations in the gene encoding for senataxin (SETX), a putative RNA:DNA helicase involved in transcription and in the maintenance of genome integrity. The gene discussed is SETX; the disease is spinocerebellar ataxia, autosomal recessive, with axonal neuropathy 2.