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, resulting in elevated chylomicron

Hyperlipoproteinemia type II

Type IIa

• Familial hypercholesterolemia

This may be sporadic (due to dietary factors), polygenic, or truly familial as a result of a mutation either in the LDL receptor gene on chromosome 19 (0.2% of the population) or the ApoB gene (0.2%).

Type IIb

The high VLDL levels are due to overproduction of substrates, including triglycerides, acetyl CoA, and an increase in B-100 synthesis. They may also be caused by the decreased clearance of LDL. Prevalence in the population is 10%.

• Familial combined hyperlipoproteinemia (FCH)
• Secondary combined hyperlipoproteinemia (usually in the context of metabolic syndrome, for which it is a diagnostic criterion)

Hyperlipoproteinemia type III

This form is due to high chylomicrons and IDL (intermediate density lipoprotein). Also known as broad beta disease or dysbetalipoproteinemia, the most common cause for this form is the presence of ApoE E2/E2 genotype. It is due to cholesterol-rich VLDL (β-VLDL). Prevalence is 0.02% of the population.

Hyperlipoproteinemia type IV

This form is due to high triglycerides. It is also known as hypertriglyceridemia (or pure hypertriglyceridemia). According to the NCEP-ATPIII definition of high triglycerides (>200 mg/dl), prevalence is about 16% of adult population.

Hyperlipoproteinemia type V

This type is very similar to type I, but with high VLDL in addition to chylomicrons. It is also associated with glucose intolerance and hyperuricemia.