Lipoprotein lipases genetic deficiency

Fig. 28.1. A schematic diagram depicting lipoprotein metabolism and the known genetic defects affecting lipoproteins. 28.1, Lipoprotein lipase (LPL) deficiency 28.2, apoC-II deficiency 28.3, apoE deficiency or mutations 28.4, hepatic lipase (HL) deficiency 28.5, LDL receptor deficiency or mutations 28.6, apoB-100 mutation in receptor binding region 28.7, apoA-I deficiency or mutations 28.7.3, ABCAl deficiency or mutations 28.8, LCAT deficiency 28.9, microsomal transfer protein (MTP) deficiency 28.10, apoB-100 synthesis or truncation mutations. Abbreviations C-II, apoC-II B, apoB E, apoE A-I, apoA-I VLDL, very-low-density lipoproteins IDL, intermediate-density lipoproteins LDL, low-density lipoproteins HDL, high-density lipoproteins LPL, lipoprotein lipase HL, hepatic lipase LCAT, lecithin cholesterol acyltransferase UC, unesterified cholesterol...

LDL-receptor deficiency. In the normal condition (a), VLDL produced by the liver loses triacylglycerol as free fatty acids (FFA) via lipoprotein lipase to peripheral tissues and then proceeds down the metabolic cascade to IDL and LDL. A major portion of these two lipoprotein species is taken up by the liver or peripheral tissues via the LDL (apo B, E) receptor. In individuals with down-regulated or genetically defective LDL receptors (b), the residence time in the plasma of IDL is increa.sed, a greater proportion being converted to LDL. LDL production and turnover time are increased, and total plasma cholesterol levels become grossly abnormal. 

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