The hepatic α-tocopherol transfer protein (TTP) is required for optimal α-tocopherol bioavailability in humans; mutations in the human TTPA gene result in the heritable disorder ataxia with vitamin E deficiency (AVED, OMIM #277460).
Ataxia with vitamin E deficiency (AVED) is a rare autosomal recessive neurodegenerative disease, due to mutations in TTPA gene (Arita et al. in Biochem J 306(Pt.2):437-443, 1995; Hentati et al. in Ann Neurol 39:295-300, 1996), which encodes for alpha-TTP, a cytosolic liver protein that is presumed to function in the intracellular transport of alpha-tocopherol.