Plasma Triglyceride Lipolysis in Multifactorial Chylomicronemia

Purpose: The mechanism of most of the multifactorial chylomicronemia (MCM) remains elusive. In order to decipher the mechanisms involved in the occurrence of this disease, plasma TG lipolysis characteristics will be monitored for 60 minutes after heparin injection instead of the 10 minutes gold standard, in a large group of genotyped MCM patients.

Method: LPL, APOC2, APOA5, GPIHB1and APOE genotypes will be determined for each patient. Basal lipid profiles including Apo B, CII, CIII, and lipoprotein lipase (LPL) concentration will be measured in 62 MCM patients, in addition to LPL activity (PHLA) T0, T10 T30 T60 minutes, Assessment of TG chylomicron decrease Study of lipoprotein remodelling by agarose gel electrophoresis.

Hypothesis To confirm the preliminary finding of high LPL activity in multifactorial chylomicronemia To explore the interest of a longer assessment of LPL activity following heparin injection. To establish if specific phenotypes could be identified among MCM patient supporting the hypothesis of different mechanisms involved (ie overproduction or defect in hepatic clearance)

Inclusion criteria

• patient with a documented history of MCM (Plasma TG concentration (TG) > 15 mmol/l or familial history of hypertriglyceridemia with TG >10 mmol/l)
• no contraindication for a single heparin injection for ex vivo LPL activity assessment

Exclusion criteria

• patients carriers of homozygous or compound heterozygous mutations on LPL, GPIHBP1, APOA5, APOC2 or APOE genes