Ataxia with oculomotor apraxia type 2: not always an easy diagnosis

Heterozygous deletion in exon 6 of STEX gene causing ataxia with oculomotor apraxia type 2 (AOA-2) with ovarian failure

Ataxia with oculomotor apraxia type 2 (AOA2), recently renamed as ATX-SETX, is an autosomal recessive, progressive neurodegenerative disorder belonging to inherited cerebellar ataxias. The pathogenic variants of the SETX gene have been implicated in ATX-SETX. We report the case of a 21-year-old woman presenting with ataxia, oculomotor apraxia and dystonia. She had elevated serum α-fetoprotein (AFP), follicle stimulating hormone (FSH) and luteinising hormone (LH) levels and moderate cerebellar atrophy. On further evaluation, she was found to have premature ovarian failure as well. Multiplex ligation-dependent probe amplification detected a heterozygous deletion in exon 6 of the SETX gene. A combination of cerebellar ataxia, oculomotor apraxia with elevated AFP and cerebellar atrophy are highly suggestive of ATX-SETX. In rare instances, it may be associated with premature ovarian failure with elevated FSH and LH levels, necessitating hormonal survey and fertility evaluation in all patients with ATX-SETX.

Ataxia with oculomotor apraxia type 2: an evolving axonal neuropathy

A 23-year-old woman had presented initially to a podiatrist complaining of poorly fitting shoes during her adolescence. After extensive neurological review, she was diagnosed with ataxia with oculomotor apraxia type 2. This is a progressive autosomal recessive ataxia associated with cerebellar atrophy, peripheral neuropathy and an elevated serum α-fetoprotein. Within Europe, it is the most frequent autosomal recessive ataxia after Friedreich's ataxia and is due to mutations in the senataxin (SETX) gene. The age of onset is approximately 15 years.The diagnosis of oculomotor apraxia type 2 is often challenging. We provide a framework for assessing a young ataxic patient with or without oculomotor apraxia and review clues that will aid diagnosis. The prognosis, level of disability, cancer and immunosuppression risk all markedly differ between the conditions. Patients and their families need the correct diagnosis for genetic counselling, management and long-term surveillance with appropriate subspecialty services.