Hyperlipidemias: Engert JC

Do R, Kiss RS, Gaudet D, Engert JC. · Department of Human Genetics, McGill University, Montreal, Quebec, Canada. · Clin Genet. · Pubmed #19054015 No free full text.

Abstract: High levels of plasma low-density lipoprotein cholesterol (LDL-C) are a significant risk factor for heart disease. Statins (3-hydroxy-3-methyl-glutaryl-CoA reductase inhibitors) have been extensively used to treat high-plasma LDL-C levels and are effective in preventing heart disease. However, statins can be associated with adverse side effects in some patients and do not work effectively in others. As an alternative to statins, the development of cholesterol-lowering agents that directly inhibit squalene synthase have shown promise. Clinical studies have shown that squalene synthase inhibitors are effective in lowering plasma levels of total cholesterol and LDL-C. Squalene synthase plays an important role in the cholesterol biosynthesis pathway as it is responsible for the flow of metabolites into either the sterol or the non-sterol branches of the pathway. In addition, variants of the squalene synthase gene appear to modulate plasma cholesterol levels in human populations and therefore may be linked to cardiovascular disease. In this review, we examine squalene synthase and the gene that codes for it (farnesyldiphosphate farnesyltransferase 1). In particular, we investigate their role in the regulation of cellular and plasma cholesterol levels, including data that suggest that squalene synthase may be involved in the etiology of hypercholesterolemia.

Sniderman A, Bailey SD, Engert JC. · Mike Rosenbloom Laboratory for Cardiovascular Research, McGill University, Montreal, Quebec, Canada. · Clin Sci (Lond). · Pubmed #17608621 No free full text.

Abstract: FCHL (familial combined hyperlipidaemia) is characterized by multiple phenotypes that are shaped by genes, the environment and time. A longitudinal study by Brouwers and co-workers, which appears in this issue of Clinical Science, points to the central role of the liver in defining the FCHL phenotypes and demonstrates how they vary over time in relation to energy excess. On the basis of their work and that of others, we propose that FCHL is a multiple gene/multiple pathway/multiple phenotype disease. The key feature of this model of common complex disease is that it posits testable faults in definable metabolic pathways, which supply the genetic underpinning of the disorder.

Marcil M, Vu H, Cui W, Dastani Z, Engert JC, Gaudet D, Castro-Cabezas M, Sniderman AD, Genest J, Cianflone K. · Centre de Recherche Hôpital Laval, Université Laval, Y2186, 2725 Chemin Ste Foy, Ste Foy, Québec, G1V 4G5. · Arterioscler Thromb Vasc Biol. · Pubmed #16627811 links to  free full text

Abstract: OBJECTIVE: A functional acylation stimulating protein (ASP) receptor, C5L2, has been recently identified in ASP-responsive cells. Impaired ASP-mediated triglyceride synthesis has previously been described in a subset of hyperapolipoprotein B/familial combined hyperlipidemia subjects. METHODS AND RESULTS: DNA sequencing of C5L2 coding region in 61 unrelated probands identified a heterozygous variant (G968-->T) in 1 subject, resulting in Ser323-->Ile substitution in the carboxyl terminal region. This variant was not detected in 2176 additional chromosomes by restriction fragment length polymorphism or fluorescence polarization genotyping. Eight family members of the proband were identified with one altered (+/-)C5L2 allele. Nine other family members had the wild-type (+/+)C5L2 sequence. The abnormal allele was associated with increased plasma triglyceride, plasma cholesterol, low-density lipoprotein (LDL) cholesterol, apolipoprotein B and ASP. Of 23 subjects tested in cell-based ASP bioactivity assays, those with C5L2(+/-) variant (n = 2) had a 50% reduction in ASP-stimulated triglyceride synthesis, glucose transport and marked reduction in maximal binding (B(max)). By contrast, a C5L2(+/+) family member responded normally, as did hyperapolipoprotein B normal ASP subjects compared with C5L2(+/+) controls (n = 6). CONCLUSIONS: The S323I variant may alter C5L2 function and might be one molecular basis contributing to familial combined hyperlipidemia.