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IEMbase 0188: AMACR-related BASD type 4

Scope

Field Value
IEMbase ID 188
Nosology 14.8.05.02
Gene AMACR
External IDs OMIM:604489; ORPHA:79095
Generated mapping MAPPED; Inborn_Disorder_of_Bile_Acid_Synthesis.yaml#BASD Type 4
Candidate DisMech targets Inborn_Disorder_of_Bile_Acid_Synthesis.yaml#BASD Type 4
Review date 2026-07-07

IEMbase phenotype signal

IEMbase represents this as AMACR-related alpha-methylacyl-CoA racemase deficiency, with alternate labels congenital bile acid synthesis defect type 4 and AMACR. Treatability is marked unknown.

The biochemical rows include increased plasma THCA and DHCA, increased plasma C27 bile acids, increased urinary taurotetrahydroxycholestanoic acid species by ESI-MS, positive AMACR sequencing, increased ASAT/ALAT and gamma-GT in selected age bands, increased serum pristanic acid, normal C26:0 fatty acid, normal-to-increased phytanic acid, increased phosphate, and decreased neonatal 25-OH vitamin D and vitamin E. Clinical rows include neonatal cholestasis, giant-cell hepatitis, jaundice, vitamin K responsive bleeding, developmental delay, epilepsy, encephalopathy, seizures, headache, cognitive decline, ataxia, dysarthria, tremor, neuropathy, spastic paraparesis, hemiparesis, pigmentary retinopathy, progressive vision loss, rhabdomyolysis, and hypothyroidism. No treatment rows are listed.

DisMech phenotype coverage

Inborn_Disorder_of_Bile_Acid_Synthesis.yaml#BASD Type 4 is the correct target. The local subtype covers AMACR, impaired peroxisomal racemization needed for bile acid side-chain beta-oxidation and phytanic acid alpha-oxidation, neonatal cholestasis and fat-soluble vitamin malabsorption, adult-onset neuropathy, retinitis pigmentosa, epilepsy, ataxia, C27 bile acid intermediates, cholic acid treatment, and dietary management.

Concordance and completeness

Judgement: correct mapped target with high concordance.

IEMbase and DisMech agree on AMACR/BASD type 4 identity, peroxisomal bile acid intermediate accumulation, neonatal cholestasis, fat-soluble vitamin issues, and later neurologic and retinal disease. IEMbase adds granular THCA, DHCA, taurotetrahydroxycholestanoic acid, pristanic acid, phytanic acid, and C26:0 distinctions, plus rhabdomyolysis, headache, hypothyroidism, and several age-specific neurologic rows. DisMech includes treatment context absent from IEMbase.

Curation actions

  • Keep this record mapped to Inborn_Disorder_of_Bile_Acid_Synthesis.yaml#BASD Type 4.
  • Consider adding THCA/DHCA, taurotetrahydroxycholestanoic acid species, pristanic acid, phytanic acid, and C26:0 diagnostic distinctions.
  • Review rhabdomyolysis, headache, hypothyroidism, and vision-loss details for possible subtype enrichment.