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Query: UMLS:C0020473 (hyperlipidemia)
 15,891 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

More than 90% of patients with type III hyperlipoproteinemia are homozygous carriers of the apolipoprotein (apo) E*2 allele. The great majority of these apoE2(Arg158-->Cys) homozygotes in the general population, however, are normolipidemic. Apparently, expression of the hyperlipidemic state requires additional genetic and/or environmental factors, suggesting a multifactorial etiology. To elucidate these additional risk factors, we analyzed normolipidemic and hyperlipidemic apoE2 homozygotes. Hyperinsulinemia was observed in 27 of 49 apoE2 homozygotes and associated with elevated lipid levels: hyperinsulinemic apoE2 homozygotes had type III hyperlipoproteinemia 6 times more often than apoE2 homozygotes with normal insulin levels (odds ratio 6.2, P=0.02). We screened the normolipidemic and hyperlipidemic apoE2 homozygotes for common variants in candidate genes involved in lipolysis-the APOA1-C3-A4 gene cluster, lipoprotein lipase, and hepatic lipase-and analyzed for associations with the expression of hyperlipidemia. In the hyperinsulinemic group, the 7 carriers of the SstI polymorphism (S2) in the APOC3 gene displayed severely elevated VLDL cholesterol (P(insulin by SstI)<0.001) and VLDL triglyceride (P(insulin by SstI)<0.01) and low levels of HDL (P(insulin by SstI)<0.02). In the normoinsulinemic group, no such relation of the SstI polymorphism with hyperlipidemia was observed. These data provide the first evidence for a combined effect of hyperinsulinemia and the SstI polymorphism on the expression of hyperlipidemia in apoE2 homozygotes.
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PMID:Severe hyperlipidemia in apolipoprotein E2 homozygotes due to a combined effect of hyperinsulinemia and an SstI polymorphism. 1055 17

The APOA1-C3-A4-A5 gene complex encodes genes whose products are implicated in the metabolism of HDL and/or triglycerides. Although the relationship between polymorphisms in this gene cluster and dyslipidemias was first reported more than 15 years ago, association and linkage results have remained inconclusive. This is due, in part, to the oligogenic and multivariate nature of dyslipidemic phenotypes. Therefore, we investigate evidence of linkage of APOC3 and HDL using two samples of dyslipidemic pedigrees: familial combined hyperlipidemia (FCHL) and isolated low-HDL (ILHDL). We used a strategy that deals with several difficulties inherent in the study of complex traits: by using a Bayesian Markov Chain Monte Carlo (MCMC) approach we allow for oligogenic trait models, as well as simultaneous incorporation of covariates, in the context of multipoint analysis. By using this approach on extended pedigrees we provide evidence of linkage of APOC3 and HDL level variation in two samples with different ascertainment. In addition to APOC3, we estimate that two to three genes, each with a substantial effect on total variance, are responsible for HDL variation in both data sets. We also provide evidence, using the FCHL data set, for a pleiotropic effect between HDL, HDL3 and triglycerides at the APOC3 locus.
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PMID:Evidence of linkage of HDL level variation to APOC3 in two samples with different ascertainment. 1456 62

Coronary heart disease is the leading cause of death in developed countries. This alarming statistic is partly attributable to lifestyle, and partly due to the genetic factors that make humans highly susceptible to atherosclerotic vascular disease. The principal metabolic causes of atherosclerosis include hyperlipidemia, hypertension, obesity, insulin resistance and diabetes mellitus. Here we discuss the aetiology of familial combined hyperlipidemia (FCHL), a highly atherogenic disorder affecting 1-2% of the Western world. Genome-wide linkage studies indicate that more than three genes contribute to the pernicious lipid profile of FCHL, and that these genes reside within the 1q21-23, 11p14.1-q12.1 and 16q22-24.1 chromosomal regions. Other loci include 1p31, 6q16.1-16.3 and 8p23.3-22, but the linkage data for these are not yet persuasive. Combined linkage and association analyses provide compelling evidence for the involvement of two distinct alleles at the APOA1/C3/A4/A5 gene cluster in the transmission of FCHL. An important lesson arising from the study of a complex genetic disorder, such as FCHL, that lacks a consensus on diagnostic criteria, is that an understanding of complex genetic disorders can derive from comparative analyses of genome-wide linkage data generated from conditions that share phenotypic overlap. The identification of potential genetic overlap between FCHL and the Metabolic Syndrome, which is estimated to affect 47 million Americans, promises to deliver new targets for reducing the risk of important conditions such as cardiovascular disease and stroke.
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PMID:Genetics of familial combined hyperlipidemia and risk of coronary heart disease. 1476 18

Several genome scans in search of high-density lipoprotein (HDL) quantitative trait loci (QTLs) have been performed. However, to date the actual identification of genes implicated in the regulation of common forms of HDL abnormalities remains unsuccessful. This may be due, in part, to the oligogenic and multivariate nature of HDL regulation, and potentially, pleiotropy affecting HDL and other lipid-related traits. Using a Bayesian Markov Chain Monte Carlo (MCMC) approach, we recently provided evidence of linkage of HDL level variation to the APOA1-C3-A4-A5 gene complex, in familial combined hyperlipidemia pedigrees, with an estimated number of two to three large QTLs remaining to be identified. We also presented results consistent with pleiotropy affecting HDL and triglycerides at the APOA1-C3-A4-A5 gene complex. Here we use the same MCMC analytic strategy, which allows for oligogenic trait models, as well as simultaneous incorporation of covariates, in the context of multipoint analysis. We now present results from a genome scan in search for the additional HDL QTLs in these pedigrees. We provide evidence of linkage for additional HDL QTLs on chromosomes 3p14 and 13q32, with results on chromosome 3 further supported by maximum parametric and variance component LOD scores of 3.0 and 2.6, respectively. Weaker evidence of linkage was also obtained for 7q32, 12q12, 14q31-32 and 16q23-24.
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PMID:Genome scan for quantitative trait loci influencing HDL levels: evidence for multilocus inheritance in familial combined hyperlipidemia. 1595 7

We report a large family in which four members showed a plasma lipid profile consistent with the clinical diagnosis of familial combined hyperlipidemia (FCHL). One of these patients was found to have markedly reduced HDL cholesterol (HDL-C) (0.72 mmol/l) and Apo A-I (72 mg/dl) levels, a condition suggestive of the presence of a mutation in one of the HDL-related genes. The analysis of APOA1 gene revealed that this patient was heterozygous for a cytosine insertion in exon 3 (c.49-50 ins C), resulting in a frame-shift and premature stop codon at position 26 of pro-Apo A-I (Q17PFsX10). This novel mutation, which prevents the synthesis of Apo A-I, was also found in four family members, including three siblings and the daughter of the proband. Carriers of Apo A-I mutation had significantly lower HDL-C and Apo A-I than non-carriers family members (0.77+/-0.15 mmol/l vs. 1.15+/-0.20 mmol/l, P<0.005; 71.4+/-9.1mg/dl vs. 134.0+/-14.7 mg/dl, P<0.005, respectively). Two of the APOA1 mutation carriers, who were also heavy smokers, had fibrous plaques in the carotid arteries causing mild stenosis (20%). The intimal-media thickness in the two other adult carriers was within the normal range. The other non-carriers family members with FCHL had either overt vascular disease or carotid atherosclerosis at ultrasound examination. This observation suggests that the low HDL-C/low Apo A-I phenotype may result from a genetic defect directly affecting HDL metabolism, even in the context of a dyslipidemia which, like FCHL, is associated with low plasma HDL-C.
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PMID:A novel mutation of the apolipoprotein A-I gene in a family with familial combined hyperlipidemia. 1795 Jul 41

The APOA1/C3/A4/A5 gene cluster encodes important regulators of fasting lipids, but the majority of lipid metabolism takes place in the postprandial state and knowledge about gene regulation in this state is scarce. With the aim of characterizing possible regulators of lipid metabolism, we studied the effects of nine single nucleotide polymorphisms (SNPs) during postprandial lipid metabolism. Eighty-eight healthy young men were genotyped for APOA1 -2630 (rs613808), APOA1 -2803 (rs2727784), APOA1 -3012 (rs11216158), APOC3 -640 (rs2542052), APOC3 -2886 (rs2542051), APOC3 G34G (rs4520), APOA4 N147S (rs5104), APOA4 T29T (rs5092), and A4A5_inter (rs1263177) and were fed a saturated fatty acid-rich meal (1g fat/kg of weight with 60% fat, 15% protein and 25% carbohydrate). Serial blood samples were extracted for 11 h after the meal. Total cholesterol and fractions [HDL-cholesterol, LDL-cholesterol, trifacylglycerols (TGs) in plasma, TG-rich lipoproteins (TRLs) (large TRLs and small TRLs), apolipoprotein A-I and apolipoprotein B] were determined. APOA1 -2803 homozygotes for the minor allele and A4A5_inter carriers showed a limited degree of postprandial lipemia. Carriers of the rare alleles of APOA4 N147S and APOA4 T29T had lower APOA1 plasma concentration during this state. APOC3 -640 was associated with altered TG kinetics but not its magnitude. We have identified new associations between SNPs in the APOA1/C3/A4/A5 gene cluster and altered postprandial lipid metabolism.
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PMID:Effects of variations in the APOA1/C3/A4/A5 gene cluster on different parameters of postprandial lipid metabolism in healthy young men. 1959 5

The relationship between alimentary lipemia and coronary disease is of great interest in view of the epidemiological and experimental evidence that underlies it. The modulation of such phenomena is influenced by both genetic and environmental factors, thus explaining their extraordinary individual variance. Over the last two decades there has been an explosion of research in this area, with often conflicting findings reported in the literature. In this study we have presented the current evidence linking a number of candidate genes (APOA1/C3/A4/A5 cluster, ABCA1, CETP, GCKR, HL, IL-6, LPL, PLIN, and TCF7L2) to the modulation of the postprandial lipid metabolism. Increased knowledge of how these and other genes influence postprandial response should increase the understanding of personalised nutrition.
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PMID:Update on genetics of postprandial lipemia. 2043 7