Gene TTPA
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Also known as
Alpha-tocopherol transfer protein, TTP, AVEDOverview
TTPA (Tocopherol Transfer Protein Alpha) encodes the alpha-tocopherol transfer protein, which is essential for maintaining normal vitamin E (alpha-tocopherol) levels in the body. This protein is primarily expressed in the liver, where it selectively binds alpha-tocopherol and facilitates its incorporation into very low-density lipoproteins (VLDL) for distribution throughout the body. Without functional TTPA, vitamin E is rapidly degraded and excreted rather than being retained.Mutations in TTPA cause ataxia with vitamin E deficiency (AVED), a rare autosomal recessive neurodegenerative disorder. Despite normal dietary intake and intestinal absorption of vitamin E, affected individuals have severely low plasma vitamin E levels, leading to progressive spinocerebellar ataxia, peripheral neuropathy, and retinopathy. Symptoms typically begin in childhood or adolescence and include loss of coordination, difficulty walking, and impaired proprioception.
Early diagnosis through genetic testing and vitamin E measurement is crucial, as high-dose vitamin E supplementation can halt disease progression and even reverse some neurological symptoms if initiated early. Understanding TTPA genetics is important for carrier screening, family planning, and identifying individuals who may benefit from preventive vitamin E therapy.