Question

Which enzyme is most likely deficient in Type I and in Type IV Hyperlipidemia? Which lipoproteins are high in plasma, respectively? Which lipoproteins accumulate in Type V hyperlipidemia?

a) Lipoprotein lipase; Type I: Chylomicrons; Type IV: VLDL; Type V: VLDL and chylomicrons
b) ACAT; Type I: LDL; Type IV: HDL; Type V: LDL
c) LCAT; Type I: VLDL; Type IV: LDL; Type V: HDL
d) HMG-CoA reductase; Type I: HDL; Type IV: VLDL; Type V: LDL

Answer 1

a) Lipoprotein lipase; Type I: Chylomicrons; Type IV: VLDL; Type V: VLDL and chylomicrons. The enzyme most likely deficient in Type I Hyperlipidemia is lipoprotein lipase (LPL), leading to elevated chylomicrons. In Type IV Hyperlipidemia, LPL is also most likely deficient, resulting in elevated VLDL. In Type V Hyperlipidemia, both VLDL and chylomicrons accumulate in the plasma.

Step-by-step explanation:

The enzyme most likely deficient in Type I Hyperlipidemia is lipoprotein lipase (LPL). This deficiency results in elevated chylomicrons, which are responsible for transferring fatty acids from the digestive tract to the liver. Since LPL is also responsible for breaking down VLDL, a defect in LPL would also result in elevated VLDL.

In Type IV Hyperlipidemia, lipoprotein lipase (LPL) is also most likely deficient. This deficiency leads to elevated VLDL in the plasma.

In Type V Hyperlipidemia, both VLDL and chylomicrons accumulate in the plasma.