SIGNIFICANT APOLIPOPROTEINS, MAJOR CLASSES OF LIPOPROTEINS, & FREDRICKSON CLASSIFICATIONOF HYPERLIPOPROTEINEMIAS

A-I (Apolipoproteins)

Plasma Conc. (mg/dL)

• 100 - 200

Main Distribution

• HDL (Surrogate marker; both inversely proportional CHD risk)

Function

• Structural

• LCAT activator

A-II (Apolipoproteins)

Plasma Conc. (mg/dL)

• 20 - 50

Main Distribution

• HDL (Surrogate marker; both inversely proportional CHD risk)

Function

• Structural

A-IV (Apolipoproteins)

Plasma Conc. (mg/dL)

• 10 - 20

Main Distribution

• CM, VLDL, HDL

Function

• Structural

B-100 (Apolipoproteins)

Plasma Conc. (mg/dL)

• 70 - 125

Main Distribution

• VLDL, IDL, LDL

Function

• Structural

• LDL-R ligand

B-48 (Apolipoproteins)

Plasma Conc. (mg/dL)

• < 5

Main Distribution

• CM

Function

• Structural

• Remnant receptor ligand

C-I (Apolipoproteins)

Plasma Conc. (mg/dL)

• 5 - 8

Main Distribution

• CM, VLDL, HDL

Function

• Structural

C-II (Apolipoproteins)

Plasma Conc. (mg/dL)

• 3 - 7

Main Distribution

• CM, VLDL, HDL

Function

• Structural

• LPL cofactor

C-III (Apolipoproteins)

Plasma Conc. (mg/dL)

• 10 - 12

Main Distribution

• CM, VLDL, HDL

Function

• Structural

• LPL inhibitor

E (Apolipoproteins)

Plasma Conc. (mg/dL)

• 3 - 15

Main Distribution

• CM, VLDL, IDL, remnants and HDL

Function

• Recognition factor that targets chylomicron and VLDL remnants to hepatic receptor

Chylomicron (Lipoprotein)

Density (mg/dL)

• < 0.93

Electrophoretic mobility

• Origin

Major Component

• Triglyceride (exogenous)

Apolipoproteins

• B48, C, E

Other comments

• Transport exogenous lipids (dietary)

VLDL (Lipoprotein)

Density (mg/dL)

• 0.93 - 1.006

Electrophoretic mobility

• Pre-B

Major Component

• Triglyceride (endogenous)

Apolipoproteins

• B100, C, E

Other comments

• Transport endogenous lipids

LDL (Lipoprotein)

Density (mg/dL)

• 1.019 - 1.063

Electrophoretic mobility

• B-region

Major Component

• Cholesterol rich (>50% by weight)

Apolipoproteins

• B100

Other comments

• Transport cholesterol to peripheral tissues (may be atherogenic - atherosclerosis)

HDL (Lipoprotein)

Density (mg/dL)

• 1.063 - 1.21

Electrophoretic mobility

• α region

Major Component

• Protein, DL approx. 50% by weight

Apolipoproteins

• AI

Other comments

• Reverse cholesterol transport (tissue to liver - for bile synthesis)

Type 1 Hyperlipoproteinemia

Particle

• CM

Representative Disorder/s

• Familial chylomicronemia

Clinical Presentation

• Eruptive xanthoma

• Acute pancreatitis

Lab Findings

• ↑ TG

Type 2a Hyperlipoproteinemia

Particle

• LDL

Representative Disorder/s

• Familial hypercholesterolemia

Clinical Presentation

• Xanthelasma & tendinous xanthoma

• premature CHD

Lab Findings

• ↑ LDL

• ↑ TC

Type 2b Hyperlipoproteinemia

Particle

• LDL, VLDL

Representative Disorder/s

• Familial combined hyperlipoproteinemia

Clinical Presentation

• Isolated xanthelasma

• premature CHD

Lab Findings

• ↑ LDL

• ↑ TC

• ↑ TG

Type 3 Hyperlipoproteinemia

Particle

• IDL (β-VLDL)

Representative Disorder/s

• Familial dysbetalipoproteinemia

Clinical Presentation

• Palmar & eruptive xanthoma

• premature CHD

Lab Findings

• ↑ TC

• ↑ TG

Type 4 Hyperlipoproteinemia

Particle

• VLDL

Representative Disorder/s

• Primary hypertriglyceridemia

Clinical Presentation

• Eruptive xanthoma

• may be associated with premature CHD

Lab Findings

• ↑ TG

• N - ↑ (TC)

Type 5 Hyperlipoproteinemia

Particle

• CM, VLDL

Representative Disorder/s

• MIxed hyperlipidemia

Clinical Presentation

• Eruptive xanthoma

• may be associated with pancreatitis & premature CHD

Lab Findings

• ↑ TG

• N - ↑ (TC)