A patient with Type V hyperlipoproteinaemia (familial hypertriglyceridaemia) presents with acute pancreatitis and eruptive xanthomata. Serum shows turbid plasma with both elevated chylomicrons and VLDL. The enzyme whose activity is PRIMARILY deficient in Type V hyperlipoproteinaemia is:

• A Hepatic lipase (HL)
• B Lipoprotein lipase (LPL), or its cofactor ApoC-II ✓
• C LCAT (Lecithin-cholesterol acyltransferase)
• D Cholesterol ester transfer protein (CETP)

Explanation

Type I and Type V hyperlipoproteinaemias both involve impaired chylomicron and VLDL clearance due to LPL deficiency or ApoC-II deficiency. LPL, anchored on capillary endothelium and activated by ApoC-II, hydrolyses TG in both chylomicrons and VLDL. Type I presents only with chylomicronaemia (childhood onset); Type V shows both chylomicrons and VLDL elevation (usually adult onset, exacerbated by diabetes or alcohol). Acute pancreatitis occurs when TG exceeds 1000 mg/dL.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.