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: Medicine
Tangier disease is characterised by which of the following lipid abnormalities? 
Select and explain. 
A. Extremely low circulating level of plasma cholesterol, B. Low level of LDL but high HDL level, C. Extremely low level of triglycerides, D. Very high level of triglycerides
A: Extremely low circulating level of plasma cholesterol
Answer: A: Extremely low circulating level of plasma cholesterol 
Explanation: Tangier disease is a very rare autosomal dominant form of extremely low plasma HDL-Cholesterol caused by mutations in the gene encoding ABCA1. Ref: Harrisons Principles of Internal Medicine, 18th Edition, Page 3154