Inheritance of endogenous hypertriglyceridaemia type IIB or IV

Area of Science:

• Human genetics
• Cardiovascular disease research
• Biochemistry

Background:

• Endogenous hypertriglyceridaemia is a lipid disorder characterized by elevated serum triglyceride levels.
• Understanding the genetic underpinnings of hypertriglyceridaemia is crucial for developing targeted therapies.
• Previous studies suggest a familial component, but the specific genetic architecture remains complex.

Purpose of the Study:

• To investigate the genetic basis of endogenous hypertriglyceridaemia in families with probands exhibiting high triglyceride levels.
• To differentiate between genetic and non-genetic forms of hypertriglyceridaemia.
• To identify the prevalence of single-type versus multiple-type familial hyperlipidaemia.

Main Methods:

• Evaluated 239 first-degree relatives of 48 probands with serum triglyceride levels > 30.0 mM.
• Classified probands based on serum cholesterol concentration (normal type IV or elevated type IIB).
• Assessed lipid profiles (triglycerides and cholesterol) to determine familial hyperlipidaemia patterns.

Main Results:

• Approximately 25% of families showed normolipidaemic relatives, indicating a non-genetic cause.
• In 75% of families, hyperlipoproteinaemia was attributed to one or more abnormal genes.
• Multiple-type (combined) familial hyperlipidaemia was identified in 30 families, significantly more common than single-type (IIB or IV) familial disease (6 families).
• Fifty percent of members in families with multiple-type lipid disorder were affected, without clear bimodality in lipid values.

Conclusions:

• Multiple-type familial hyperlipidaemia is the primary driver of elevated serum triglycerides in over half of moderate to severe cases.
• Pure familial endogenous hypertriglyceridaemia is relatively rare.
• The genetic abnormality underlying familial hypertriglyceridaemia may be heterogeneous, potentially requiring kinetic or enzyme studies for further differentiation.