Hyperlipoproteinemias

A group of disorders characterized by increased plasma lipoproteins. According to fredrickson: They can be classified into 5 types Each of which may be familial or acquired .

1- Type I, Hyperlipoproteinemias:
• The familial type is due to deficiency of lipoprotein lipase enzyme
• Characterized by increased plasma chylomicrons and somewhat VLDL, but LDL and HDL are reduced
• There is marked increase in plasma triacylglycerol s & some increase in plasma cholesterol may occur
• The plasma is turbid

2-TypeII, Hyperbetalipoproteinemia:
• Characterized by increased plasma LDL
• The familial type is caused by reduced LDL metabolism due to defective LDL receptors
• There is marked increase in plasma cholesterol (familial hypercholesterolemia)
• Plasma is clear
• The acquired type occurs in hypothyroidism
3-Type III, Dysbetalipoproteinemia
• Characterized by increased VLDL, (IDL) & chylomicrons remnants
• The plasma is turbid
• There is hypercholesterolemia & hypertriacylglycerodemia
• The familial type is caused by defective apo E necessary for uptake and metabolism of VLDL and chylomicron remnants by liver
4- Type IV, Hyperprebetalipoproteinemia
• Characterized by increased plasma VLDL , triacylglycerol s & some increase in plasma cholesterol
• The plasma is turbid
• The familial type is due to increased formation of triacylglycerol s from carbohydrates
• The acquired type occurs in severe type II DM, obesity & alcoholism