Ataxia neuropathy spectrum

Ataxia neuropathy spectrum (ANS) is a group of mitochondrial diseases caused by mutations in the POLG gene, which encodes the catalytic subunit of mitochondrial DNA polymerase gamma. This spectrum encompasses conditions previously known as mitochondrial recessive ataxia syndrome (MIRAS), sensory ataxia neuropathy dysarthria and ophthalmoplegia (SANDO), and spinocerebellar ataxia with epilepsy (SCAE). ANS primarily affects the nervous system, including both the central and peripheral nervous systems, and is characterized by a combination of cerebellar ataxia (impaired coordination and balance), sensory neuropathy (damage to nerves that carry sensation), and in many cases, epilepsy. The key clinical features of ANS include progressive cerebellar ataxia, peripheral sensory neuropathy (often with loss of proprioception and vibration sense), dysarthria (slurred speech), and external ophthalmoplegia (weakness of the eye muscles limiting eye movement). Seizures, including status epilepticus, can be a prominent and sometimes life-threatening feature. Additional findings may include myoclonus, cognitive decline, migraine-like headaches, and liver dysfunction. The age of onset is variable but most commonly presents in young adulthood, typically between the teenage years and the fourth decade of life. There is currently no cure for ataxia neuropathy spectrum. Treatment is supportive and symptomatic, focusing on management of seizures with appropriate anticonvulsants (notably avoiding sodium valproate due to the risk of liver toxicity in POLG-related disorders), physical and occupational therapy for ataxia and neuropathy, and speech therapy for dysarthria. Monitoring for hepatic complications is important. Genetic counseling is recommended for affected individuals and their families. Prognosis varies considerably, with some patients experiencing a slowly progressive course and others having more rapid neurological decline, particularly when epilepsy is severe.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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