Clinical and molecular findings of ataxia with oculomotor apraxia type 2 in 4 families.

BACKGROUND Ataxia with oculomotor apraxia type 2 (AOA2) is an autosomal recessive disease caused by SETX mutations in 9q34 resulting in cerebellar ataxia in association with peripheral neuropathy, cerebellar atrophy on imaging, an elevated alpha-fetoprotein (AFP) serum level, and occasional oculomotor apraxia. OBJECTIVE To describe the clinical and molecular findings of 7 patients with a clinical presentation of AOA2 and their relatives. DESIGN Case report. SETTING Projet Hospitalier de Recherche Clinique. PATIENTS Seven patients with AOA2 and their family members. INTERVENTION Linkage analysis and direct sequencing of all exons of SETX were performed in all patients. Magnetic resonance imaging and electroneuromyography were performed and the patients' AFP serum levels were tested. RESULTS We identified 7 patients with AOA2 from 4 unrelated families. Three novel SETX mutations were found. The clinical picture of the patients reported is fairly homogeneous and in accordance with the classic AOA2 presentation: onset from 13 to 18 years of progressive cerebellar ataxia and areflexia. Oculomotor apraxia was detected in 1 patient. Predominant axonal neuropathy and a diffuse cerebellar atrophy were found in the 4 patients tested. All patients had elevated AFP serum levels and 5 of 8 nonsymptomatic heterozygous relatives had moderately increased AFP serum levels as well. CONCLUSIONS Ataxia with oculomotor apraxia type 2 is a homogeneous form of cerebellar ataxia with occasional oculomotor apraxia. Most nonsymptomatic heterozygous carriers present with increased AFP serum levels.