Which Fredrickson Type corresponds to familial hypercholesterolemia due to LDL receptor defect (high LDL and total cholesterol)?

• A. Type IIa
• B. Type IIb
• C. Type III
• D. Type IV

Answer: (A)

Understanding the pattern of which lipoproteins are elevated helps identify the Fredrickson type. In this scenario, only LDL is elevated (leading to high LDL and total cholesterol) while triglycerides remain normal. That specific pattern points to Type IIa. It arises from defective LDL receptors (or ApoB-100 issues) that reduce clearance of LDL from the blood, causing familial hypercholesterolemia with markedly increased LDL cholesterol.

Other patterns involve additional lipid elevations: Type IIb features both LDL and VLDL elevation with higher triglycerides; Type III (dysbetalipoproteinemia) shows abnormal remnant particles with increased cholesterol and triglycerides; Type IV is mainly elevated triglycerides due to excess VLDL.