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IEMbase 0506: USF1-related familial combined hyperlipidemia

Scope

Field Value
IEMbase ID 506
Nosology 15.3.20.01
Gene USF1
External IDs OMIM:144250; OMIM:602491
Generated mapping MAPPED; HIGH; Hyperlipidemia.yaml#Familial Combined Hyperlipidemia
Candidate DisMech targets Hyperlipidemia.yaml#Familial Combined Hyperlipidemia
Review date 2026-07-07

IEMbase phenotype signal

IEMbase represents USF1-related familial combined hyperlipidemia, also named hyperlipoproteinemia type 2B / FCHL / HLP type 2, as a complex-trait lipid disorder with unknown inheritance in the local JSON. No treatments are listed. Biochemical rows include decreased HDL cholesterol, increased LDL cholesterol, increased serum triglyceride, and increased plasma Apo B. Clinical rows include arcus cornealis, xanthelasma, carotid bruits, femoral bruits, and adult myocardial ischemia.

DisMech phenotype coverage

Hyperlipidemia.yaml#Familial Combined Hyperlipidemia is the correct local target. The local hyperlipidemia entry has a Familial Combined Hyperlipidemia subtype characterized by elevated total cholesterol, LDL cholesterol, and/or triglycerides with variable expression among affected family members. The file also models shared dyslipidemia mechanisms including hepatic apoB-containing lipoprotein clearance, VLDL overproduction, impaired LPL/ApoC-III regulation, atherogenic lipoprotein infiltration of arterial intima, foam-cell formation, fibrous plaque formation, coronary artery disease, and lipid-lowering treatments.

Concordance and completeness

Judgement: correct generated mapping with moderate-to-high phenotype concordance.

IEMbase and DisMech agree on the FCHL identity and on the mixed LDL/TG/HDL dyslipidemia phenotype with atherosclerotic/coronary consequences. IEMbase adds more specific prompts for USF1, Apo B elevation, xanthelasma, arcus cornealis, carotid and femoral bruits, and myocardial ischemia timing. The current DisMech entry does not visibly model USF1 as a gene-level susceptibility locus, so the subtype coverage is clinically correct but incomplete at the gene-specific IEMbase level.

Curation actions

  • Keep the mapping to Hyperlipidemia.yaml#Familial Combined Hyperlipidemia.
  • Consider adding USF1 as a susceptibility/modifier gene only with verified evidence, because the DisMech target is a broad complex-trait hyperlipidemia entry.
  • Consider future enrichment for Apo B elevation, arcus cornealis, xanthelasma, and peripheral bruit prompts if they fit the entry's intended scope.