At a Glance The lipodystrophies are a group of rare, genetic or acquired disorders characterized by generalized (nearly the entire body) or partial (limbs only) loss of body fat, with fat hypertrophy in other depots when partial. They are marked by the abnormal degenerative condition of the body’s adipose tissue, which is associated with severe…
At a Glance Tangier Disease is a very rare recessive disorder caused by mutations in the adenosine triphosphate (ATP)-binding cassette transporter A1 (ABCA1) gene that impairs ABCA1 function. As ABCA1 effluxes excess cell cholesterol and phospholipid during the biogenesis of high-density lipoprotein (HDL), such mutations result in the build-up of cholesterol in the peripheral tissues…
At a Glance The presence of corneal opacities, markedly reduced high-density lipoprotein (HDL) levels, hypertriglyceridemia with reduced or normal low-density lipoprotein (LDL) levels, and increased very low-density lipoprotein (VLDL) levels may be indicative of familial LCAT deficiency (FLD) or fish-eye disease (FED). These rare disorders are caused by different mutations in the LCAT gene that…
At a Glance Hypoalphalipoproteinemia, or low levels of high-density lipoprotein cholesterol (HDL-C), is quite prevalent in the United States, according to the third National Health and Nutrition Examination Survey (NHANES III). Approximately 35% of adult men have HDL less than 40 mg/dL and 39% of women have HDL less than 50 mg/dL. The common, mild…
At a Glance Hypoalphalipoproteinemia, or low levels of high-density lipoprotein cholesterol (HDL-C), is quite prevalent in the United States, according to the third National Health and Nutrition Examination Survey (NHANES III). Approximately 35% of adult men have HDL less than 40 mg/dL and 39% of women have HDL less than 50 mg/dL. The common, mild…
At a Glance Familial apolipoprotein CII deficiency is a very rare (rarer than LPL deficiency) autosomal recessive disorder in which apolipoprotein CII (apoC-II), a cofactor for LPL, is absent, the clearance of chylomicrons from the blood is greatly impaired and triglycerides (TG) accumulate in the plasma. Very low-density lipoproteins (VLDL) may also be elevated. Because…
At a Glance This rare autosomal recessive disorder (frequency 1 per million) is characterized by the absence of lipoprotein lipase (LPL) activity. A founder effect renders the frequency of this disease much higher in certain populations, such as French-Canadians (1:5000). LPL is a key enzyme involved with the hydrolysis of triglycerides (TG) in plasma to…
At a Glance Familial dysbetalipoproteinemia (type III hyperlipoproteinemia) is a genetic disorder characterized by the accumulation of remnants of triglyceride-rich lipoproteins (chylomicrons and very low density lipoproteins or VLDL) in the plasma. The remnant particles are susceptible to uptake by macrophages in peripheral tissues, which may become cholesterol-laden foam cells and lead to atherosclerosis. The…
At a Glance Familial combined hyperlipidemia (FCH) is the most common genetically determined dyslipoproteinemia with a prevalence of 1 in 100. FCH is characterized by an increase in cholesterolemia and/or triglyceridemia in at least two members of the same family, with intra-individual (over time) and intra-familial variability of the lipid phenotype. Increased carotid artery intima-media…
At a Glance High-density lipoprotein cholesterol (HDL-C) levels are inversely correlated with risk for coronary heart disease (CHD): an increase of 1 mg/dL of HDL-C is associated with a 2% and 3% decrease in risk for CHD in men and women, respectively. Hyperalphalipoproteinemia, or increased circulating levels of HDL-C, are commonly due to genetic mutations.…
