Lipoprotein disorders causes

Lipoprotein Disorders Microchapters
Patient Information
Overview
Causes
Classification Hyperlipoproteinemia Hypolipoproteinemia
Treatment

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Hyperlipidemia can occur as either a primary event or secondary to some underlying disease. The primary hyperlipidemias include chylomicronemia, hypercholesterolemia, dysbetalipoproteinemia, hypertriglyceridemia, mixed hyperlipoproteinemia, and combined hyperlipoproteinemia. Other diseases, such as diabetes mellitus, pancreatitis, renal disease, and hypothyroidism, can cause the secondary form.

Causes

Primary hyperlipidemia

Hyperlipoproteinemia type I

• Deficiency of lipoprotein lipase (LPL) or altered apolipoprotein C2

Hyperlipoproteinemia type II

Type IIa

• Familial hypercholesterolemia
  • Sporadic (due to dietary factors)
  • Polygenic (multiple abnormalities in LDL metabolism)
  • Truly familial (as a result of a mutation in the LDL receptor gene on chromosome 19 (0.2% of the population), the apo B gene (0.2%) or the proprotein convertase subtilisin kexin 9 (PCSK9) gene (very rare))

Type IIb

• Familial combined hyperlipoproteinemia (FCH)
  • Overproduction of hepatically-derived apo B-100 associated with VLDL
  • Overproduction of substrates, including triglycerides and acetyl-CoA
  • Decreased clearance of LDL

Hyperlipoproteinemia type III

• Presence of apo E E2/E2 genotype resulting in cholesterol-rich VLDL (β-VLDL)

Hyperlipoproteinemia type IV

• Genetic defect, which is passed on in an autosomal dominant fashion

Hyperlipoproteinemia type V

• Very similar to type I, but with high VLDL in addition to chylomicrons
• Associated with glucose intolerance and hyperuricemia

Secondary hyperlipidemia

Secondary to some underlying "non-lipid" etiology.

• Type 2 diabetes mellitus
• Nephrotic syndrome
• Chronic renal failure
• Cholestatic liver diseases
• Hypothyroidism
• Smoking
• Obesity
• Drugs
  • Oral estrogens
  • Thiazide diuretics
  • Beta blockers
  • Atypical antipsychotic agents, such as clozapine and olanzapine
  • Antiretroviral drugs used for HIV infection, in particular the protease inhibitors