Familial Hypertriglyceridemia

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Summary

Familial hypertriglyceridemia, also known as type IV hyperlipoproteinemia, is an autosomal dominant disorder that is defined by an isolated elevation of VLDL. This may have a number of possible causes, such as a heterozygous LPL-inactivating mutation, a hepatic overproduction of VLDL, or a decrease in VLDL clearance. Since VLDL carries triglycerides, hypertriglyceridemia is therefore a hallmark of the disease. High triglyceride levels are also a common cause of pancreatitis, which therefore may also be seen. Finally, the disease is often accompanied by insulin resistance.

Key Points

  • Familial Hypertriglyceridemia
    • Also known as type IV hyperlipoproteinemia
    • Genetics
      • Autosomal dominant
        • This disease is fairly common
    • Pathophysiology
      • Possible causes:
        • Heterozygote for LPL-inactivating mutation
        • Hepatic overproduction of VLDL
        • Decreased removal of VLDL
    • Clinical Features
      • Elevated VLDL elevated triglycerides
        • This is the definition of familial hypertriglyceridemia
        • Compare / contrast with familial hyperchylomicronemia, which is also characterized by elevated VLDL / triglycerides
      • Pancreatitis
        • Caused by increased triglycerides
      • Often accompanied by insulin resistance
        • You may get premature atherosclerosis because of this, but you shouldn’t think of this familial hypertriglyceridemia as one of the CVD hyperlipoproteinemias. Those are hyperlipoproteinemias types II and III.
      • No CVD / premature atherosclerosis
      • Turbid serum
        • Contrast against familial hyperchylomicronemia, in which the serum has a creamy layer
        • I like to think of familial hypertriglyceridemia as a less severe form of familial hyperchylomicronemia