Ataxia with Isolated Vitamin E Deficiency (TTPA)
Ataxia with isolated vitamin E deficiency is an autosomal recessive, pan-ethnic disorder that is caused by pathogenic variants in the gene TTPA. Most individuals will present with symptoms during puberty, including progressive ataxia, clumsiness of the hands, loss of proprioception (sense of how the body is positioned), and areflexia (absence of neurological reflexes). Affected individuals also tend to experience decreased visual acuity. When untreated, the majority of individuals become wheelchair dependent between 11-50 years of age. The set of symptoms and disease severity is variable, even within families. Several specific variants have been associated with the early or late-onset form of the disease, and therefore the age of onset may be predicted in some individuals based on the genotype.
For information about carrier frequency and residual risk, please see the residual risk table.