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TTPA gene

Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

TTPA gene

The TTPA gene provides instructions for making the alpha-tocopherol transfer protein, which is essential for distributing vitamin E throughout the body.

Normal Function

The TTPA gene provides instructions for making the α-tocopherol transfer protein (αTTP), which is found in the liver and brain. This protein controls the distribution of vitamin E obtained from the diet (also called α-tocopherol) to cells and tissues throughout the body. Vitamin E is an antioxidant that protects cells in the body from the damaging effects of unstable molecules called free radicals.

Normally, vitamin E derived from food is absorbed in the intestine and transported into the liver on molecules called chylomicrons. Once in the liver, αTTP transfers vitamin E from chylomicrons to very low-density lipoproteins (VLDLs), which carry fat, fat-soluble vitamins, and cholesterol from the liver to other tissues. The VLDLs are then released into the bloodstream so the vitamin E can be used. The αTTP protein is also thought to transport vitamin E to nerve cells (neurons) in the brain.

Health Conditions Related to Genetic Changes

Ataxia with vitamin E deficiency

More than 20 mutations in the TTPA gene have been found to cause ataxia with vitamin E deficiency. This condition is characterized by neurological problems, including difficulty coordinating movements (ataxia), due to a buildup of free radicals. As a result of these mutations, the body cannot retain or use dietary vitamin E, leading to reduced blood levels of the vitamin and the accumulation of free radicals.

  • Severe forms: Mutations that result in no functional αTTP protein being made are associated with severe ataxia that begins at a young age.
  • Milder forms: Mutations that reduce but do not eliminate protein function are associated with milder ataxia that occurs at a later age and progresses more slowly.
  • Retinitis pigmentosa: A specific mutation (His101Glu or H101Q) found in the Japanese population is associated with an eye disorder called retinitis pigmentosa, which causes vision loss in people with this condition.

Other Names for This Gene

  • alpha-tocopherol transfer protein
  • alphaTTP
  • ataxia (Friedreich-like) with vitamin E deficiency
  • ATTP
  • AVED
  • tocopherol (alpha) transfer protein
  • TTP1
  • TTPA_HUMAN

Frequently Asked Questions

key distinguishing feature is that patients with TTPA mutations have low blood levels of vitamin E despite normal dietary intake, whereas other forms of ataxia usually have normal vitamin E levels. Diagnosis often involves measuring serum alpha-tocopherol levels and confirming the presence of mutations in the TTPA gene. Unlike some other ataxias, the neurological symptoms in TTPA-related deficiency can be significantly improved or stabilized with high-dose vitamin E supplementation, which serves as both a diagnostic and therapeutic test.
The primary treatment is lifelong, high-dose oral vitamin E supplementation. The dosage is much higher than the standard daily recommendation and is typically adjusted based on body weight and blood levels. It is crucial to monitor blood vitamin E levels regularly to ensure they remain in the therapeutic range. Early initiation of treatment is critical to prevent further neurological damage and to potentially reverse some early symptoms.
While symptoms often begin in childhood, typically between ages 5 and 10, the condition can present in adulthood if the diagnosis was missed earlier. Adults may present with progressive ataxia, sensory neuropathy, and loss of reflexes. Because the underlying genetic defect persists, adults require the same lifelong high-dose vitamin E therapy as children to manage the condition and prevent progression.
Without treatment, the accumulation of free radicals leads to progressive and irreversible damage to the nervous system. Long-term complications include severe gait ataxia, loss of muscle strength, and sensory deficits. In severe cases, individuals may become wheelchair-bound and experience significant difficulties with coordination and balance. Early diagnosis and consistent vitamin E supplementation can halt progression and improve stability, but damage that has already occurred may not be fully reversible.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.