Hyperlipoproteinemia

DISORDERS OF PLASMA LIPOPROTEINS (DYSLIPOPROTEINEMIA)

HYPERLIPOPROTEINEMIA

• There is an elevation of circulating lipoproteins.
• Fredrickson’s Classification of hyperlipoproteinemia are of 5 types-

I. Type I (familial lipoprotein lipase deficiency)

• Deficiency of lipoprotein lipase or apo C-II.
• Elevated levels of chylomicrons
• Triglyceride level is increased.

Clinical features-

• Acute pancreatitis
• Eruptive xanthoma
• Hepatosplenomegaly

Treatment-

• Gene therapy. 

II. Type II- 2 types

1. Type IIa ( familial hypercholesterolemia)

• Due to deficiency of functional LDL receptors.
• LDL cholesterol is raised.
• Four classes of mutation have been defined for LDL receptors-

1. Class I (most common)- loss of receptor synthesis
2. Class II- receptors are synthesized but not translocated to cell membrane
3. Class III- Receptor binds poorly to apo B-100
4. Class IV- receptor binds to apo B-100 but no interilization.

2. Type IIb ( familial combined hyperlipedimia)

• LDL and VLDL are increased

III. Type III (familial dysbetalipoproteinemia)- Broad β- disease

• Due to abnormalities in apo- E
• Chylomicron remnants and VLDL remnants(IDL) are increased.
• Triglyceride and cholesterol increased.

IV. Type IV (familial hypertriglyceridemia)

• Deficiency of apo-A- V.
• Increased VLDL level

V.  Type V (Endogenous hypertriglyceridemia)

• Increased VLDL and chylomicrons.