Ataxia with vitamin E deficiency

Ataxia with vitamin E deficiency (AVED), also known as familial isolated vitamin E deficiency or ataxia with isolated vitamin E deficiency, is a rare inherited neurodegenerative disorder caused by mutations in the TTPA gene (alpha-tocopherol transfer protein gene) on chromosome 8q12. This gene encodes the alpha-tocopherol transfer protein, which is essential for incorporating vitamin E (alpha-tocopherol) into very low-density lipoproteins in the liver for distribution throughout the body. When this protein is deficient or dysfunctional, vitamin E levels in the blood become severely reduced, leading to progressive neurological damage. The disease primarily affects the nervous system, particularly the cerebellum and peripheral nerves. The clinical presentation closely resembles Friedreich ataxia and typically begins in childhood or adolescence, usually between ages 5 and 15. Key features include progressive cerebellar ataxia (difficulty coordinating movements), dysarthria (slurred speech), loss of proprioception (position sense), areflexia (absent deep tendon reflexes), and a positive Babinski sign. Some patients may also develop retinitis pigmentosa leading to visual impairment, cardiomyopathy, scoliosis, and head titubation. Without treatment, the disease is progressively disabling. AVED is one of the few treatable hereditary ataxias. Early and lifelong oral supplementation with high-dose vitamin E (typically 800–1200 mg/day of alpha-tocopherol) can halt disease progression and, in some cases, partially reverse neurological symptoms, particularly if treatment is initiated before significant irreversible damage has occurred. Serum vitamin E levels should be monitored regularly to ensure adequate supplementation. The prognosis is significantly improved with early diagnosis and consistent treatment, underscoring the importance of measuring serum vitamin E levels in any patient presenting with progressive ataxia, especially when Friedreich ataxia has been excluded.

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