Familial hypertriglyceridaemia

Familial hypertriglycidaemia 2.3-10 mmol/L

This condition has an autosomal dominant inheritance. This condition is characterised by increased VLDL only (high VLDL production, decreased lipoprotein lipase activity) [Fredrickson type IV]. This condition occurs in approximately 1% of general population and 5% of MI survivors <60 yr old.

Features often include:

• often overweight
• >30 yr old
• often diabetic
• hyperuriaemic
• may or may not have premature CHD - determined by family history and HDL-C

This condition is exacerbated by environmental factors such as obesity, alcohol intake, use of thiazide diuretics, use of the oral contraceptive pill and glucocorticoids.

Severe hypertriglyceridemia >10 mmol/L

This is characterised by increased plasma levels of chylomicrons and VLDL (high VLDL production, decreased lipoprotein lipase activity) [Fredrickson type V]. When fasting triglycerides exceed 10 mmol/L chylomicrons will also be a major contributor to hyperlipidaemia - this is because chylomicrons and VLDL compete for the same clearance mechanism in the circulation (lipoprotein lipase).

Rarely severe hypertriglyceridaemia is caused by familial lipoprotein lipase deficiency (inherited as an autosomal recessive trait) - usually this is due to a mutation in the lipoprotein lipase gene but occasionally it results from a deficiency of apo CII, the activator of lipoprotein lipase.

Features often include:

• usually middle-aged
• often obese
• often hyperuricaemic
• usually diabetic
• risk for recurrent pancreatitis

The patient may present with eruptive xanthomas (elbows, back, buttocks), lipaemic retinalis, abdominal pain, hepatosplenomegaly and an increased risk of pancreatitis (with TG > 10 mol/l). Associated features include impaired glucose tolerance or overt diabetes and hyperuricaemia.