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IEMbase 0660: ACOX2-related congenital bile acid synthesis defect

Scope

Field Value
IEMbase ID 660
Nosology 14.8.06.02
Nosology code IEM0784
Gene ACOX2
External IDs OMIM:617308
Generated mapping MAPPED to Inborn_Disorder_of_Bile_Acid_Synthesis.yaml
Candidate DisMech targets Broad bile-acid umbrella only; no exact ACOX2 subtype found
Review date 2026-07-07

IEMbase phenotype signal

IEMbase represents autosomal recessive ACOX2-related congenital bile acid synthesis defect, abbreviated CBAS6.

Biochemical rows include low-to-normal plasma C24 bile acid, increased plasma and urinary C27 bile acid, normal-to-increased ASAT/ALAT and transaminase, low serum cholesterol, low plasma 25-hydroxyvitamin D, and normal serum pristanic acid. Clinical rows include optional childhood ataxia, cognitive dysfunction, liver fibrosis, and steatorrhea, plus optional adolescent cholestasis.

DisMech phenotype coverage

Inborn_Disorder_of_Bile_Acid_Synthesis.yaml is the correct broad disease-family context. It covers deficient primary bile acid production, toxic C27 bile-acid intermediate accumulation, cholestasis, progressive liver injury, steatorrhea, fat-soluble vitamin malabsorption, and neurologic involvement in selected subtypes.

The local umbrella entry does not currently define an ACOX2/CBAS6 subtype. Its subtype list focuses on HSD3B7, AKR1D1, CYP7B1, AMACR, CYP27A1, BAAT, and related disorders. Therefore, the generated mapping is biologically relevant but not complete at the gene-specific row level.

Concordance and completeness

Judgement: broad family-level coverage only; exact ACOX2/CBAS6 coverage remains a local gap.

DisMech captures the general bile-acid synthesis logic and several IEMbase phenotypes, especially C27 bile-acid accumulation, cholestasis, steatorrhea, and fat-soluble vitamin deficiency. It does not preserve ACOX2 as the causal gene, the C24-versus-C27 bile-acid contrast, normal pristanic acid, low cholesterol, or the childhood/adolescent age-banded neurologic and hepatic prompts.

Curation actions

  • Keep Inborn_Disorder_of_Bile_Acid_Synthesis.yaml as broad context, not exact ACOX2 subtype coverage.
  • Consider adding an ACOX2/CBAS6 subtype or separate disease entry after source review.
  • Preserve C24/C27 bile-acid directionality, transaminases, cholesterol, 25-hydroxyvitamin D, pristanic acid, ataxia, cognitive dysfunction, steatorrhea, cholestasis, and liver-fibrosis prompts.