A 3-year-old boy presents with recurrent episodes of pancreatitis, xanthomas over the elbows and buttocks, and a family history of early cardiovascular disease. Fasting lipid profile shows triglycerides 1800 mg/dL and cholesterol 450 mg/dL. Lipoprotein electrophoresis shows increase in IDL (Type III pattern). Which genetic disorder is this?
- A Familial hypercholesterolemia (LDL receptor defect)
- B Familial dysbetalipoproteinemia (Type III hyperlipoproteinemia, apoE2/E2 genotype) ✓
- C Familial lipoprotein lipase deficiency (Type I, chylomicronemia)
- D Tangier disease (ABCA1 deficiency)
Explanation
Familial dysbetalipoproteinemia (Type III hyperlipoproteinemia) is caused by the apolipoprotein E2/E2 genotype, which impairs clearance of chylomicron remnants and IDL (intermediate density lipoprotein). The hallmark is elevation of both cholesterol and triglycerides with accumulation of IDL. Tuberous and palmar xanthomas are characteristic. Familial LPL deficiency (Type I) causes extreme hypertriglyceridemia with chylomicronemia and eruptive xanthomas but cholesterol is not dramatically elevated. Familial hypercholesterolemia has primarily elevated LDL-cholesterol with tendon xanthomas.
Reference: Ghai Essential Pediatrics, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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