Spinocerebellar ataxias (SCAs) are a group of progressive and irreversible neurological diseases affecting gait and movement coordination. Many result from cerebellar degeneration or the impairment of a portion of the neuroaxis that contributes to cerebellar inflow or outflow. Spinocerebellar ataxia with axonal neuropathy (SCAN1) is characterized by late-childhood-onset, recessive ataxia with peripheral axonal motor and sensory neuropathy, distal muscular atrophy, and pes cavus and stepagge gait. All affected individuals have normal intelligence. Diagnosis of SCAN1 is based on clinical findings, family history, MRI, and nerve conduction studies. To date, there are only symptomatic treatments for SCAN1; physical therapy may help maintain a more active lifestyle. The only reported SCAN1 patients are from an extended Saudi Arabian family with nine affected individuals.
Takashima et al. (2002) studied the molecular bases in an extended Saudi family with nine affected members with autosomal recessive SCAN1. All affected members had normal intelligence. They evaluated three of the nine patients; these individuals had cerebellar ataxia and axonal neuropathy. One of the patients had a history of seizures, and two had mid brain atrophy. All the three patients had mild hypercholesterolemia and borderline hypoalbuminemia. By performing a genome-wide screening and sequencing, a homozygous transition mutation (A1478G) in the TPD1 gene was found in the nine affected members, which encodes tryosyl-DNA phosphodiesterase 1.