A 35-year-old man with xanthomas on his Achilles tendons and corneal arcus presents with chest pain. Vital signs: BP 165/95 mmHg, HR 92/min, RR 16/min, Temp 37°C. Labs reveal LDL-cholesterol 450 mg/dL, HDL 28 mg/dL, triglycerides 180 mg/dL. Coronary angiography shows significant stenosis. DNA testing confirms a mutation in the LDL receptor gene preventing normal cell membrane translocation. No xanthoma eruptivum noted. Which intracellular consequence results from this mutation?
- A)Inability to internalize LDL particles, preventing suppression of HMG-CoA reductaseGABARITO
- B)Decreased synthesis of apolipoprotein B-100 due to SREBP-2 inactivation
- C)Impaired esterification of intracellular cholesterol by ACAT
- D)Reduced activity of cholesterol 7α-hydroxylase in the endoplasmic reticulum
- E)Impaired degradation of cholesterol to pregnenolone in mitochondria
Explicação
When LDL receptors cannot reach the cell surface due to translocation defects, hepatocytes cannot internalize LDL particles. This prevents the normal feedback suppression of HMG-CoA reductase by intracellular cholesterol, causing continued upregulation of HMG-... Ver explicação completa e trilha adaptativa →