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Lipoproteins and Plasma Lipids - Coggle Diagram
Lipoproteins and Plasma Lipids
Apolipoprotein Expression
ApoA-1
Associated lipoprotein
Chylomicron
HDL
Function: LCAT activator
ApoB-48
Associated lipoprotein
Chylomicron
Function: Secretion into circulation
ApoB-100
Associated lipoprotein
VLDL
IDL
LDL
Function: Binds LDL receptor
ApoC-II
Associated lipoprotein
Chylomicron
VLDL
HDL
Function: LPL activator
ApoE
Associated lipoprotein
All except LDL
Function: Binds LDL receptor
Lipoprotein composition
Hydrophobic core of TG and cholesteryl ester
Polar lipids on surface
Apolipoproteins
Lipoprotein metabolism
Endogenous pathway
VLDL carries TG and cholesterol from liver to peripheral tissue
VLDL becomes IDL via LPL
IDL becomes LDL via hepatic lipase
LDL binds to LDL receptors on the liver for clearance
Exogenous pathway
Intake of fat in the intestines
Chylomicrons formed by intestinal enterocytes
Chylomicrons enter lymphatic system, then into bloodstream
In blood, chylomicrons receive ApoC-II and ApoE from HDL
LPL breaks down chylomicrons into chylomicron remnants, sending FFA to peripheral tissue
Chylomicron remnants bind to liver for clearance
Dyslipidemia phenotypes
Type 1
Familial chylomicronemia syndrome (exogenous hyperlipemia)
Abnormally increased chylomicrons
Massive hypertriglyceridemia
Associated genes
LPL, APOC2, APOC5, GPIHBPI, LMF1
Type 2a
Familial hypercholesterolaemia
Abnormally increased LDL and cholesterol
Normal TG levels
Associated genes
LDLR, APOB, PCSK9
Type 2b
Combined hyperlipidemia
Increased Lp(a)
Increased LDL and VLDL
Elevated TG and cholesterol
Associated genes
LPA, polygenic
Type 3
Dysbetalipoproteinemia
Increased IDL
APOE
Type 4
Hypertriglyceridemia
Increased VLDL
Elevated TG
Polygenic
Type 5
Polygenic chylomicronemia
Increased chylomicrons
Increased VLDL
Increased TG
Peripheral signs
Xanthomas
Homozygous familial hypercholesterolemia
Treatment
LDL apheresis every 1-4 weeks
Pre=emptive liver transplantation
Risk of coronary heart disease is high, as early as 12yo
Cerebrotendinous xanthomatosis
Autosomal recessive
Complications
Chronic diarrhoea
Premature cataracts, osteoporosis
Progressive neurological dysfunction
Caused by CYP27A1 mutations
Presents with elevated cholestanol levels
Sitosterolemia
Caused by ABCG5 or ABCG8 deficiency
Causes increased GI absorption of plant sterols
Autosomal recessive
Complications
Premature atherosclerosis
Haemolytic anaemia, large platelets