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IEMbase 0658: TTPA-related alpha-tocopherol transfer protein deficiency

Scope

Field Value
IEMbase ID 658
Nosology 21.11.01.02
Nosology code IEM0270
Gene TTPA
External IDs OMIM:277460; ORPHA:96
Generated mapping MAPPED to Familial_Isolated_Vitamin_E_Deficiency.yaml
Candidate DisMech targets Familial_Isolated_Vitamin_E_Deficiency.yaml
Review date 2026-07-07

IEMbase phenotype signal

IEMbase represents autosomal recessive TTPA-related alpha-tocopherol transfer protein deficiency, also labeled ataxia with isolated vitamin E deficiency (AVED). Treatability is marked yes.

Biochemical rows include decreased plasma vitamin E from childhood onward, adolescent/adult increases in cholesterol and triglyceride, and broad beta lipoprotein electrophoresis. Clinical rows include adolescent/adult ataxia, brain MRI abnormality, dystonia, optional areflexia, optional dysarthria, and adult xanthomas.

DisMech phenotype coverage

Familial_Isolated_Vitamin_E_Deficiency.yaml is the correct local target. It models TTPA/alpha-TTP loss, impaired hepatic alpha-tocopherol transfer into lipoproteins, systemic vitamin E deficiency, oxidative neuronal injury, progressive ataxia, proprioceptive/sensory involvement, areflexia, dysarthria, dystonia, retinal disease, occasional cardiomyopathy, and vitamin E supplementation.

The DisMech entry is stronger than IEMbase for mechanistic detail and treatment rationale. IEMbase adds compact age-banded prompts for brain MRI abnormality, adult xanthomas, hypercholesterolemia, hypertriglyceridemia, and broad beta lipoprotein electrophoresis that are not prominent in the local entry.

Concordance and completeness

Judgement: correct exact mapping with high concordance.

The gene, disease name, inheritance, key biochemical readout, and neurologic phenotype are aligned. Remaining differences are mostly granularity: IEMbase tracks some lipid/lipoprotein and imaging rows that could be reviewed if the DisMech AVED entry is expanded.

Curation actions

  • Accept Familial_Isolated_Vitamin_E_Deficiency.yaml as the disease-level target.
  • Preserve IEMbase prompts for low vitamin E, ataxia, dystonia, areflexia, dysarthria, brain MRI abnormality, xanthomas, cholesterol, triglyceride, and broad beta lipoprotein electrophoresis.
  • If updating the local entry later, review whether lipid/xanthoma findings are disease-core, modifier, or source-specific.