Primary hyperchylomicronemia is characterized by a marked hypertriglyceridemia due to the accumulation of chylomicron. The main clinical symptoms of this disorder are a huge increase in plasma triglyceride and cholesterol, and the presence of xanthomatous eruption, lipemia retinalis, hepatosplenomegaly, and the complication of acute pancreatitis. The genetic basis for primary hyperchylomicronemia is heterogeneous. Familial chylomicronemia (known as Fredrickson's classification of type 1 hyperlipoproteinemia) [DS:H00154] is a clinical condition showing the severest hypertriglyceridemia and is classically represented by two rare genetic disorders, i.e., familial lipoprotein lipase (LPL) deficiency and familial apolipoprotein C-II deficiency. Even rarer conditions such as circulating inhibitors of lipoprotein lipase and the presence of autoantibodies also cause type 1 hyperlipoproteinemia. More recently, patients with primary hyperchylomicronemia caused by mutations in the gene for glycosylphosphatidylinositol-anchored high density lipoprotein-binding protein 1 (GPIHBP1) or lipase maturation factor 1 (LMF1) were found. By contrast, the more commonly encountered polygenic chylomicronemia of adulthood, referred to as mixed dyslipidemia (known as type 5 hyperlipoproteinemia) [DS:H00157], can present later in life and is characterized by increased levels of hepatically derived triglyceride-rich lipoproteins and triglyceride-rich remnant particles together with reduced levels of HDL cholesterol.
