system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
In Familial hypercholesterolemia there is deficiency of
assistant
The correct answer is  LDL receptors 

Familial hypercholesterolemia (type IIa) is due to deficiency of functional LDL receptors as a result of different types of mutations.