Lipoprotein lipase gene analyses in one Turkish family and three different Chinese families with severe hypertriglyceridaemia: one novel and several established mutations.
Amino acid substitution (Ile194----Thr) in exon 5 of the lipoprotein lipase gene causes lipoprotein lipase deficiency in three unrelated probands. Support for a multicentric origin.
The primary LPL deficiency was diagnosed on the basis of the findings that no LPL activity was detected in post-heparin plasma (PHP) and that the immunoreactive LPL mass in PHP was less than 2% of the control level.
We conclude that primary LPL deficiency in the proband was caused by a lack of enzyme synthesis due to the absence of LPL mRNA resulting from one base deletion of G in exon 5, and that heterozygous LPLArita deficient subjects show almost half value of control LPL mass.
The measurement of LPL activity and mass allows identification of the heterozygote state for LPL deficiency, which is characterized by variable expressions of hyperlipidemia and reduced HDL cholesterol.
Two distinct first-order rates of inactivation were obtained and the derived constants used to calculate the lipoprotein lipase and hepatic lipase contributions to the total post-heparin triglyceride hydrolase activity in normal controls and in patients with familial hyperchylomicronaemia.
Familial chylomicronemia is an autosomal recessive disease characterised by fasting triglyceridemia and an absence of lipoprotein lipase (LpL) activity in post-heparin plasma.
Loss of Col18 reduces plasma levels of Lpl enzyme and activity, which results in mild fasting hypertriglyceridemia and diet-induced hyperchylomicronemia.
A familial type I hyperlipoproteinaemia is described in three members of a family of eleven; on the basis of LPL activity and HDL content of plasma three other members of the family have been diagnosed to be heterozygotes without other disturbances in their lipid spectrum.
We studied the molecular basis of familial Type I hyperlipoproteinemia in two brothers of Turkish descent who had normal plasma apolipoprotein C-II levels and undetectable plasma post-heparin lipoprotein lipase (LPL) activity.
Familial hyperchylomicronemia due to the lipoprotein lipase (LPL) activity deficiency (Type I hyperlipoproteinemia) is an autosomal recessive disorder with a prevalence estimated at one case per million.
This mutation was not present among 20 FCHL patients with normal plasma LPL levels nor has it been reported among individuals with familial LPL deficiency.
Determination of lipoprotein lipase (LPL) activity is important for hyperchylomicronemia diagnosis, but remains both unreliable and cumbersome with current methods.
We conclude that the Ile194 to Thr194 and Arg243 to His243 substitutions occur in lipoprotein lipase regions essential for normal enzyme activity and each mutation results in the expression of a nonfunctional enzyme leading to the hyperchylomicronemia syndrome manifested in the proband.
Familial chylomicronemia is a recessive disorder that may be due to mutations in lipoprotein lipase (LPL) and in other proteins such as apolipoprotein C-II and apolipoprotein A-V (activators of LPL), GPIHBP1 (the molecular platform required for LPL activity on endothelial surface), and LMF1 (a factor required for intracellular formation of active LPL).
From this genetic model of LPL deficiency in SM and AT, it can be concluded that CM-specific LPL expression is a major determinant in the regulation of plasma TG and HDL-cholesterol levels.