This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
True regarding familial hypercholesterolemia is: 
Select and explain. 
A. Deficient VLDL receptors, B. Deficient HDL receptors, C. HMG CoA reductase deficiency, D. Deficient LDL receptors
D: Deficient LDL receptors
Answer: D: Deficient LDL receptors 
Explanation: Familial hypercholesterolemia have defective LDL receptorsMany patients with familial hypercholesterolemia have mutations in the LDLR gene that encodes the LDL receptor protein, which normally removes LDL from the circulation, or apolipoprotein B (ApoB), which is the pa of LDL that binds with the receptor.Patients who have one abnormal copy (are heterozygous) of the LDLR gene may have premature cardiovascular disease at the age of 30 to 40.Having two abnormal copies (being homozygous) may cause severe cardiovascular disease in childhood.Patients may have xanthelasma palpebrarum, yellowish patches consisting of cholesterol deposits above the eyelids.