Causes and Natural History of Dyslipidemias

The lipoprotein transport system is vital to the delivery of the hydrophobic fats that are carried in the aqueous environment of the blood. The lipoprotein particles that comprise this system are polydisperse and contain triglycerides, free and esterified cholesterol, phospholipids and proteins. Inborn errors in the lipoprotein transport system lead to alterations in both the steady state concentrations of the various lipoproteins and in the metabolism of these particles. These inborn errors lead to both hyperlipoproteinemia and hypolipoproteinemia. Profound changes in the ambient lipoprotein concentrations have a variety of clinical manifestations. The present study protocol is designed to permit a full plasma evaluation of the lipids, lipoproteins and apolipoproteins, in patients with potential genetic defects in these processes. We will use a variety of research plasma assays. These specialized plasma assays are necessary to correctly diagnose and treat patients that present with the more unusual disorders of lipid metabolism; these patients cannot be diagnosed by standard, CLIA- Certified assays and may require tissue or blood cells for diagnosis and adequate treatment. The study population will include patients which are referred to the Lipid Service, Cardiovascular Branch, NHLBI from private care providers, academic institutions or the NHLBI-MDB website, with any of the following potential lipid abnormalities or clinical stigmata associated with dyslipoproteinemias: a) increased plasma levels of cholesterol, triglycerides, HDL-cholesterol or LDL-cholesterol b) decreased plasma concentrations of cholesterol and HDL-cholesterol c) postprandial hyperlipidemia or d) eruptive xanthomas, xanthelasma, tuberous or tendinous xanthomas, or corneal opacities.

• INCLUSION CRITERIA:
• Children >= 2 years of age and >12 kg and adults
• Dyslipidemia subjects of interest the group

The following is a representative list of the types of patient presentations with dyslipidemia and potential diagnoses eligible for this protocol:

• Plasma cholesterol levels >200 mg/dl or <120 mg/dl includes patients with diagnoses such as familial hypercholesterolemia, familial combined hyperlipidemia, sitosterolemia, lipoprotein lipase, hepatic lipase or apo-CII deficiency, and dysbetalipoproteinemia.
• Plasma LDL-C levels >130 mg/dl or <70 mg/dl includes patients with diagnoses such as familial hypercholesterolemia, PCSK9, apo3500, familial combined hyperlipidemia, sitosterolemia, dysbetalipoproteinemia, abetalipoproteinemia and hypobetalipoproteinemia.
• Plasma HDL-C levels >70 mg/dl or <25 mg/dl includes patients with deficiency of cholesteryl ester transfer protein, lecithin cholesterol acyltransferase, phospholipid transfer protein, lipoprotein lipase, hepatic lipase, or apo-CII, ANGPTL3, and Tangier disease.
• Plasma triglyceride levels >150 mg/dl includes patients with deficiency of lipoprotein lipase, hepatic lipase or apoC-II, GPIHBP1, LMF1, dysbetalipoproteinemia, Type I, Type IV and Type V hyperlipidemia.