General description

Ataxia with isolated vitamin E deficiency (AVED) is a rare autosomal recessive disorder caused by pathogenic variants in the α-tocopherol transfer protein (αTTP) gene, leading to impaired vitamin E transport. It typically manifests in childhood, between the ages of 6 and 18 years, with progressive neurological symptoms resembling Friedreich's ataxia (FA) but with fewer cardiac and diabetic complications.

The primary symptom is progressive cerebellar ataxia, resulting in coordination difficulties, dysarthria, clumsiness, and dystonic movements. Patients often experience sensory abnormalities, including lower limb areflexia, peripheral neuropathy, and proprioceptive deficits. Other neurological signs include pyramidal spasticity and an extensor plantar reflex (Babinski sign). Some individuals also develop retinitis pigmentosa, leading to vision loss.

Unlike Friedreich's ataxia (FA), AVED is treatable with vitamin E supplementation. Therefore, measuring blood vitamin E levels is essential when Friedreich's ataxia is suspected.