A 6-year-old boy with failure to thrive and chronic steatorrhea presents with BP 95/60, HR 98, RR 22, temp 37°C, SpO2 98%. He reports fat-soluble vitamin deficiencies (A, D, E, K) causing night blindness and bone pain. Laboratory studies reveal elevated serum cholesterol (320 mg/dL) and triglycerides (480 mg/dL) despite severe fat malabsorption. Plasma apolipoprotein B is undetectable. PT/INR is prolonged. Which genetic mutation best explains this paradoxical lipid profile?
- A)Microsomal triglyceride transfer protein (MTP) deficiency preventing chylomicron and VLDL assemblyGABARITO
- B)Primary defect in long-chain fatty acid oxidation causing lipid accumulation in intestine
- C)Lipoprotein lipase deficiency with severe hypertriglyceridemia and chylomicron accumulation
- D)Abetalipoproteinemia secondary to pancreatic insufficiency and fat malabsorption
- E)Mutations in apolipoprotein B gene preventing normal protein synthesis
Explicação
Abetalipoproteinemia is caused by MTP (microsomal triglyceride transfer protein) deficiency. MTP is essential for assembling apoB-containing lipoproteins (chylomicrons in enterocytes and VLDL in hepatocytes). Without functional MTP, dietary lipids cannot be in... Ver explicação completa e trilha adaptativa →