Search PubMed⌕ Search

Biomedical subjects

G M Dallinga-Thie

Publications and source records attributed to G M Dallinga-Thie.

At least 37 records · Page 2Linked to original sources
PubMed2001

New genetic variants in the apoA-I and apoC-III genes and familial combined hyperlipidemia.

Linkage and association between the apolipoprotein (apo) A-I/C-III/A-IV gene region on chromosome 11 and familial combined hyperlipidemia (FCHL) has been observed previously. Using sequence analysis two new allelic variants were identified, C(317) -T in intron 2 of the apoA-I gene and C(1100)-T in exon 3 of the apoC-III gene. These variants were studied in 30 FCHL probands, 159 hyperlipidemic relatives, 327 normolipidemic relatives, and 218 spouses. The allele frequencies of both variants were significantly different in probands and spouses (P < 0.002 and P < 0.001, respectively), with increased frequency of the minor alleles in the probands. The minor genotypes (TT) were associated with elevated plasma triglyceride and apoC-III. Both variants were in strong, although not complete, linkage disequilibrium with each other and with the MspI site in the promoter region of the apoA-I gene and the SstI site in the 3' untranslated region of exon 4 of the apoC-III gene. Haplotypes based on these four variants were constructed and the distributions of haplotype combinations were significantly different (P < 0.0001). Two distinct haplotypes predisposing to FCHL were found: 2-2-1-2 and 1-2-2-2 (MspI, C(317) -T; SstI, C(1100)-T). The haplotype combinations carrying one of these high risk alleles are associated with elevated lipid levels in probands and in spouses. While these effects can be attributed to the presence of the M2 and S2 minor alleles, these results suggest that the importance of specific allelic haplotypes may be greater than single genotypic effects.

Adult↗
PubMed2001

Genetic heterogeneity in the apolipoprotein C-III promoter and effects of insulin.

In the present study, we have investigated the in vivo and in vitro role of two newly identified variants (G(-)944A and A(-)1180C) located in the upstream promoter region of the apolipoprotein C-III (apoC-III) gene. These variants were studied in 30 probands diagnosed with FCHL, their relatives, and spouses. The allele frequencies of both variants were not different between the groups. No significant associations between plasma lipid traits and DNA variants were observed. We further analyzed the effect of the presence of these variants in the upstream enhancing region of the apoC-III gene, as five different in vivo occurring haplotypes, on the transcriptional activity of apoC-III in both HepG2 and Caco-2 cells. All five promoter constructs, including the wild type, showed similar enhancing activity of the apoC-III gene. The average transcription efficiency was enhanced 19-fold in HepG2 cells and 11-fold in Caco-2 cells. Previous studies have shown in vitro insulin-dependent down-regulation of the apoC-III gene transcription in HepG2 cells by DNA variation in an insulin response element (IRE) in the apoC-III promoter. We observed a 30% insulin-dependent down-regulation of apoC-III expression that was, however, independent of the presence of the two IRE variants. In contrast, in Caco-2 cells, a more variable insulin-dependent up-regulation was found that was also independent of the presence of the IRE variants.In conclusion, our data suggested that the apoC-III gene transcription in vitro is regulated by insulin but independent of the presence of the two IRE variants at -455 and -482. We were unable to detect associations between these apoC-III variants and plasma lipids and insulin in our FCHL population. This means that in vivo apoC-III transcription not only depends upon insulin but appears to be mediated by other mechanisms.

Apolipoprotein C-III↗
PubMed2000

High dose of simvastatin normalizes postprandial remnant-like particle response in patients with heterozygous familial hypercholesterolemia.

Familial hypercholesterolemia (FH) and disturbances in postprandial lipoprotein metabolism are both associated with premature atherosclerosis. The effect of beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitors on plasma cholesterol levels in patients with FH is well established; however, it is not known whether postprandial lipoproteins are also influenced. In this case-controlled intervention study, we investigated the effects of high-dose simvastatin on postprandial lipoproteins. We used a new method to analyze remnant lipoproteins based on the immunoseparation principle (remnant-like particle cholesterol [RLP-C] assay) and the well-established measurement of retinyl ester (RE) analysis in plasma and in the Svedberg flotation unit (Sf)<1000 fraction. Seven heterozygous FH patients and 7 control subjects matched for sex, age, body mass index, triglycerides, and apolipoprotein E genotype were enrolled in the study. An oral vitamin A (RE) fat-loading test was performed at baseline in both groups and after 3 months of high-dose simvastatin (80 mg/d) treatment in the FH patients. Before treatment, FH patients had significantly higher fasting and postprandial concentrations of lipoprotein remnants (plasma RLP-C 42+/-19 mg/dL and area under the RLP-C curve 415+/-82 mg. L(-1). h(-1), respectively) than did control subjects (7+/-3 mg/dL and 101+/-35 mg. L( -1). h(-1), respectively; P<0.05), suggesting a delayed clearance of chylomicron remnant particles in the FH patients. Treatment with simvastatin significantly reduced fasting and postprandial remnant lipoprotein cholesterol concentrations (13+/-3 mg/dL and 136+/-53 mg. L(-1). h(-1), respectively; P<0.05 for both). Postprandial RE in the Sf<1000 fraction, not total RE in plasma, was also significantly higher in FH patients than in control subjects (24+/-10 versus 6.3+/-5.9 mg. L( -1). h(-1), P<0.05), but treatment with simvastatin did not result in improvement of the postprandial RE response, either in the Sf<1000 fraction or in plasma. It is concluded that heterozygous FH patients have increased fasting and postprandial remnant lipoprotein concentrations. Treatment with simvastatin significantly reduced the fasting and postprandial RLP-C concentrations but did not result in improved postprandial RE response.

Apolipoproteins↗
PubMed2000

Growth hormone (GH) treatment decreases postprandial remnant-like particle cholesterol concentration and improves endothelial function in adult-onset GH deficiency.

Premature atherosclerosis is a clinical feature in adult-onset GH deficiency. Evidence is accumulating that disturbances in triglyceride metabolism, reflected by abnormalities in circulating remnant lipoproteins, are associated with increased atherogenic potential. In a case-controlled intervention study, we investigated postprandial lipoprotein metabolism using a new remnant lipoprotein method based on immunoseparation principle [RLP-cholesterol (RLP-C)]. In addition, we analyzed retinyl ester (RE) analysis in plasma and in Sf < 1000 fraction. Endothelial function was assessed as flow-mediated dilatation (FMD). Eight patients diagnosed with acquired adult-onset GH deficiency and eight controls matched for gender, age, body mass index, and apolipoprotein (apo) E genotype were enrolled in the study. Oral vitamin A fat loading tests were performed at baseline in both groups and after 6 months of treatment with recombinant human GH (rh-GH) in the adult-onset GH-deficient patients. Adult-onset GH-deficient patients had significantly higher fasting RLP-C, postprandial RLP-C concentrations (plasma RLP-C, 0.29 +/- 0.14 mmol/L; and incremental area under the curve-RLP-C, 2.13 +/- 1.60 mmol*h/L, respectively) than controls (0.19 +/- 0.06 mmol/L and 1.05 +/- 0.72 mmol*h/L (P: < 0.05), respectively). They also had significantly higher postprandial RE in plasma and Sf < 1000 fraction. Treatment with rh-GH significantly reduced postprandial RLP-C concentrations (incremental area under the curve-RPL-C 0.73 +/- 0.34 mmol*h/L; P: < 0.05) but had no effects on the fasting RLP-C concentrations (0.317 +/- 0.09 mmol/L, P: < 0.05), or on the postprandial RE in plasma and in Sf < 1000 fraction. Endothelial function measured as FMD was improved from 5.9 +/- 3.3% to 10.2 +/- 4.0% (P: < 0.05) in patients treated with rh-GH. It is concluded that patients with adult-onset GH deficiency have increased levels of fasting and postprandial RLP-C and an impaired endothelial function as measured as FMD. Treatment with rh-GH resulted in a decrease of postprandial RLP-C concentration, thereby improving the postprandial atherogenic lipoprotein profile and improvement of endothelial function, however, the clearance of large chylomicron particles as reflected by RE remained disturbed.

Adult↗
PubMed1999

Dietary counselling effectively improves lipid levels in patients with endogenous hypertriglyceridemia: emphasis on weight reduction and alcohol limitation.

OBJECTIVE: To evaluate the short-term effect of dietary counselling in patients with endogenous hypertriglyceridemia and evaluate the effects of advised nutrient changes. DESIGN: A prospective dietary intervention study in patients with endogenous hypertriglyceridemia from January I st 1988 to December 31 st 1996 according to the Dutch guidelines for a healthy diet. Before and after the dietary intervention period of 12 weeks, 24h food recalls were used to assess dietary intake and macronutrient composition. Effectiveness was evaluated by assessment of body weight, serum lipids, lipoproteins and insulin resistance parameters. SETTING: Leiden outpatient Lipid Clinic. SUBJECTS: Forty-five newly diagnosed, untreated patients with endogenous hypertriglyceridemia. RESULTS: A significant reduction in energy intake and body weight as well as changes in macronutrient composition were observed. Total serum triacylglycerol and cholesterol levels decreased by 31% and 15%, respectively. No effects were observed on serum glucose and insulin levels. Weight reduction was significantly correlated with reduction of total plasma triacylglycerol levels and inversely correlated with changes in HDL cholesterol levels. Of all nutrients assessed, only reduction of alcohol intake correlated with improvement of total serum triacylglycerol. CONCLUSIONS: Short-term dietary counselling in patients with endogenous hypertriglyceridemia can effectively improve serum lipid and lipoprotein levels. With regard to the advised nutrient changes, weight loss and limitation of alcohol intake prove to be the best predictors of triacylglycerol reduction.

Adult↗
PubMed1999

A genome scan for familial combined hyperlipidemia reveals evidence of linkage with a locus on chromosome 11.

Familial combined hyperlipidemia (FCHL) is a common familial lipid disorder characterized by a variable pattern of elevated levels of plasma cholesterol and/or triglycerides. It is present in 10%-20% of patients with premature coronary heart disease. The genetic etiology of the disease, including the number of genes involved and the magnitude of their effects, is unknown. Using a subset of 35 Dutch families ascertained for FCHL, we screened the genome, with a panel of 399 genetic markers, for chromosomal regions linked to genes contributing to FCHL. The results were analyzed by use of parametric-linkage methods in a two-stage study design. Four loci, on chromosomes 2p, 11p, 16q, and 19q, exhibited suggestive evidence for linkage with FCHL (LOD scores of 1.3-2.6). Markers within each of these regions were then examined in the original sample and in additional Dutch families with FCHL. The locus on chromosome 2 failed to show evidence for linkage, and the loci on chromosome 16q and 19q yielded only equivocal or suggestive evidence for linkage. However, one locus, near marker D11S1324 on the short arm of human chromosome 11, continued to show evidence for linkage with FCHL, in the second stage of this design. This region does not contain any strong candidate genes. These results provide evidence for a candidate chromosomal region for FCHL and support the concept that FCHL is complex and heterogeneous.

Adult↗
PubMed1999

Linkage of a candidate gene locus to familial combined hyperlipidemia: lecithin:cholesterol acyltransferase on 16q.

Familial combined hyperlipidemia (FCHL) is a common lipid disorder characterized by elevated levels of plasma cholesterol and triglycerides that is present in 10% to 20% of patients with premature coronary artery disease. To study the pathophysiological basis and genetics of FCHL, we previously reported recruitment of 18 large families. We now report linkage studies of 14 candidate genes selected for their potential involvement in the aspects of lipid and lipoprotein metabolism that are altered in FCHL. We used highly polymorphic markers linked to the candidate genes, and these markers were analyzed using several complementary, nonparametric statistical allele-sharing linkage methodologies. This current sample has been extended over the one in which we identified an association with the apolipoprotein (apo) AI-CIII-AIV gene cluster. We observed evidence for linkage of this region and FCHL (P<0.001), providing additional support for its involvement in FCHL. We also identified a new locus showing significant evidence of linkage to the disorder: the lecithin:cholesterol acyltransferase (LCAT) locus (P<0.0006) on chromosome 16. In addition, analysis of the manganese superoxide dismutase locus on chromosome 6 revealed a suggestive linkage result in this sample (P<0.006). Quantitative traits related to FCHL also provided some evidence of linkage to these regions. No evidence of linkage to the lipoprotein lipase gene, the microsomal triglyceride transfer protein gene, or several other genes involved in lipid metabolism was observed. The data suggest that the lecithin:cholesterol acyltransferase and apolipoprotein AI-CIII-AIV loci may act as modifying genes contributing to the expression of FCHL.

Adult↗
PubMed1999

Association of plasma lipids and apolipoproteins with the insulin response element in the apoC-III promoter region in familial combined hyperlipidemia.

The apoAI-CIII-AIV gene cluster, located on chromosome 11, contributes to the phenotype of familial combined hyperlipidemia (FCH), but this contribution is genetically complex. Combinations of haplotypes, based on three restriction enzyme polymorphisms: XmnI and MspI sites, 5' of the start site of the apoA-I gene and SstI polymorphism in the 3' untranslated region of exon 4 of the apoC-III gene, were analyzed to characterize their effect on the expression of severe hyperlipidemia. An epistatic interaction was demonstrated: the S2 allele on one haplotype was synergistic in its hyperlipidemic effect to the X2M2 allele on the other haplotype (Dallinga-Thie, G. M. et al. J. Clin. Invest. 1997. 99: 953-961). In the present study two additional polymorphic sites in the insulin response element (IRE) of the apoC-III gene promoter, T-455C: FokI restriction site, C-482T: MspI restriction site, were studied in 34 FCH pedigrees including 34 probands, 220 hyperlipidemic relatives, 300 normolipidemic relatives, and 236 spouses. In contrast to the earlier data for the other polymorphisms in this gene cluster (XmnI, MspI/AI, and SstI), there were no differences in frequency distributions of the T-455C and the C-482T variants between probands, hyperlipidemic and normolipidemic relatives and spouses. No significant associations between plasma lipid traits and DNA variants in the IRE were observed. Analysis of combinations of haplotypes based on the five polymorphisms in the gene cluster provided further evidence for a dominant role of the SstI polymorphism as a major susceptibility locus in FCH. The inclusion of the IRE markers did not improve genetic informativeness, nor our understanding of the observed synergistic relationship associated with the high risk combination of haplotypes in FCH families.

Adult↗
PubMed1998

Cholesterol crystallization in human gallbladder bile: relation to gallstone number, bile composition, and apolipoprotein E4 isoform.

Patients with multiple cholesterol gallstones are at increased risk of recurrence after nonsurgical therapy, possibly because of fast biliary cholesterol crystallization. Serum apolipoprotein E4 (apo E4) is a risk factor for primary cholesterol gallstone formation as well as recurrence. We examined potential effects of stone number and apolipoprotein E genotype on crystallization and on various crystallization-influencing factors in gallbladder biles of 36 cholesterol stone patients (25 multiple stones: 10 carrying the epsilon4 allele). Biliary cholesterol saturation, bile salt composition or concentrations of total protein, immunoglobulin (Ig)A, IgG, alpha1-acid glycoprotein, haptoglobin, or mucin--all crystallization promoters--did not differ between multiple and solitary stone patients, apparently not explaining different speed of crystallization (crystal observation time 3.5 +/- 0.6 days vs. 12.7 +/- 2.4 days, respectively; P = .0003). In contrast, biliary aminopeptidase-N activities (2,607 +/- 592 mU/mL vs. 947 +/- 185 mU/mL; P = .04) were higher and IgM levels (179 +/- 39 vs. 65 +/- 8 mg/L; P = .09) tended to be higher in the case of multiple stones. Although patients carrying the epsilon4 allele had similar stone numbers and crystallization as patients without the epsilon4 allele, their cholesterol saturation index (CSI) was lower (1.08 +/- 0.09 vs. 1.54 +/- 0.13; P = .01), whereas total protein and bile salt concentrations tended to be higher with preferential taurine-conjugation. In conclusion, fast cholesterol crystallization is associated with multiple stones but not with apolipoprotein E4. Whereas fast crystallization may contribute to high recurrence rates after nonsurgical therapy in case of multiple gallstones, the mechanism for increased risk of gallstone formation in patients carrying the epsilon4 allele remains unknown.

Apolipoprotein E4↗
PubMed1998

Families with familial combined hyperlipidemia and families enriched for coronary artery disease share genetic determinants for the atherogenic lipoprotein phenotype.

Small, dense LDL particles consistently have been associated with hypertriglyceridemia, premature coronary artery disease (CAD), and familial combined hyperlipidemia (FCH). Previously, we have observed linkage of LDL particle size with four separate candidate-gene loci in a study of families enriched for CAD. These loci contain the genes for manganese superoxide dismutase (MnSOD), on chromosome 6q; for apolipoprotein AI-CIII-AIV, on chromosome 11q; for cholesteryl ester transfer protein (CETP) and lecithin:cholesterol acyltransferase (LCAT), on chromosome 16q; and for the LDL receptor (LDLR), on chromosome 19p. We have now tested whether these loci also contribute to LDL particle size in families ascertained for FCH. The members of 18 families (481 individuals) were typed for genetic markers at the four loci, and linkage to LDL particle size was assessed by nonparametric sib-pair linkage analysis. The presence of small, dense LDL (pattern B) was much more frequent in the FCH probands (39%) than in the spouse controls (4%). Evidence for linkage was observed at the MnSOD (P=.02), CETP/LCAT (P=.03), and apolipoprotein AI-CIII-AIV loci (P=.005) but not at the LDLR locus. We conclude that there is a genetically based association between FCH and small, dense LDL and that the genetic determinants for LDL particle size are shared, at least in part, among FCH families and the more general population at risk for CAD.

Adult↗
PubMed1998

Preferential clearance of apoB-48-containing lipoproteins after heparin-induced lipolysis is modulated by lipoprotein lipase activity.

The acute effects of intravenous heparin administration (50 U/kg body weight) on apolipoprotein (apo)B-48 and apoB-100-containing lipoproteins in relation to postheparin lipase activities were studied in ten healthy normolipidemic volunteers. Five subjects returned to receive sham injections with saline. Lipoproteins were separated from plasma by density gradient ultracentrifugation at baseline, 3, and 20 min postheparin. ApoB-48 and apoB-100 in d < 1.006 g/mL and 1.006 < d < 1.019 g/mL fractions were quantitatively measured after electrophoresis on 5% SDS polyacrylamide gels and Coomassie-blue staining. No significant changes were observed after saline injections. Heparin administration released lipoprotein lipase (LPL) and hepatic lipase (HL) activities after 20 min, and significantly reduced apoB-48 concentrations in d < 1.006 g/mL fractions only. ApoB-100 concentrations showed a trend to decrease in d < 1.006 g/mL fractions and to increase in 1.006 < d < 1.019 g/mL fractions. LPL activity was related to the percentual disappearance of apoB-48 (r = 0.81, P = 0.004) and apoB-100 (r = 0.91, P < 0.001) in d < 1.006 g/mL fractions. When little LPL was released (LPL activity < 120 mU/mL) by heparin, apoB-48 was preferentially eliminated over apoB-100. However, when abundant LPL was released (LPL activity > 140 mU/mL), comparable percentual reductions for apoB-48 and apoB-100 were seen. Pharmacokinetic analysis revealed first-order kinetics for the clearance of apoB-48 in d < 1.006 g/mL fractions, but zero-order kinetics for apoB-100 clearance. Under conditions of artificially enhanced lipolysis, the first catabolic step of apoB-48-containing lipoproteins and hepatic VLDL showed different pharmacokinetics. ApoB-48-containing lipoproteins were the preferred substrate for LPL, and only when abundant LPL was present, clearance of hepatic VLDL occurred.

Adolescent↗
PubMed1997

Complex genetic contribution of the Apo AI-CIII-AIV gene cluster to familial combined hyperlipidemia. Identification of different susceptibility haplotypes.

Familial combined hyperlipidemia (FCH) is a common genetic lipid disorder in Western societies. In a recent report (Dallinga-Thie, G.M., X.D. Bu, M. van Linde-Sibenius Trip, J.I. Rotter, A.J. Lusis, and T.W.A. de Bruin. J. Lipid Res., 1996, 36:136-147) we have studied three restriction enzyme polymorphisms: XmnI, and MspI sites 5' of the apo AI gene and SstI site in the 3' untranslated region of exon 4 of the apo CIII gene in 18 FCH pedigrees, including 18 probands, 178 hyperlipidemic relatives, 210 normolipidemic relatives, and 176 spouses. DNA variations in the apo AI-CIII-AIV gene cluster had a modifying effect on plasma triglycerides, LDL cholesterol, and apolipoprotein CIII levels. In this study, combinations of haplotypes were analyzed to further characterize their interactions and effect on the expression of severe hyperlipidemia in FCH subjects. A specific combination of haplotypes with one chromosome carrying the X1M1S2 (1-1-2) haplotype and the other the X2M2S1 haplotype (2-2-1) was significantly more frequent in hyperlipidemic relatives (6%) than in normolipidemic relatives (3%) and spouses (0.5%). Associated with this combination of haplotypes were significantly elevated plasma cholesterol (P < 0.0001), triglycerides (P < 0.0001), and apo CIII (P < 0.001) levels when compared to the wild type combination of haplotypes 1-1-1/1-1-1. The only spouse with this specific combination of haplotypes showed a severe hyperlipidemic phenotype, similar to FCH. Furthermore, nonparametric sibpair linkage analysis revealed significant linkage between these markers in the gene cluster and the FCH phenotype (MspI P = 0.0088, SstI P = 0.044, and XMS haplotype P = 0.037). The present findings confirm that the apo AI-CIII-IV gene cluster contributes to the FCH phenotype, but this contribution is genetically complex. An epistatic interaction between different haplotypes of the gene cluster was demonstrated. The S2 allele on one haplotype was synergistic to the X2M2 allele on the other haplotype in its hyperlipidemic effect. Therefore, two different susceptibility loci exist in the gene cluster, demonstrating the paradigm of complex genetic contribution to FCH.

Adult↗
PubMed1996

Apolipoprotein E4 genotype and gallbladder motility influence speed of gallstone clearance and risk of recurrence after extracorporeal shock-wave lithotripsy.

Extracorporeal shock-wave lithotripsy (ESWL) is an effective treatment in selected gallstone patients, but stone recurrence is a major drawback. Factors potentially influencing gallstone clearance and recurrence were studied in 84 patients in whom stone dissolution was diagnosed after ESWL plus bile salt therapy for initial solitary (n = 55) or multiple (n = 29) radiolucent stones. Apolipoprotein E (apoE) genotyping and gallbladder motility (sonography) were studied in a representative subgroup of patients (n = 50). The median follow-up after ESWL was 36 months (range, 4.5-67 months). Gallstone clearance was achieved after 8.7 months (range, 0.2-30 months). Independent factors significantly enhancing gallstone clearance were the presence of E4 allele; small initial gallstone size and number; effectiveness of fragmentation; and good gallbladder emptying (P = .002). Gallstone recurrence was seen in 30 patients after 18.6 months (range, 1.0-50 months). Cumulative gallstone recurrence rate (life-table analysis) was 15% within 1 year, increasing to 60% within 5.5 years. Although the probability of gallstone recurrence tended to be smaller in patients with initial solitary stones than in those with multiple stones during early follow-up, differences disappeared after long-term follow-up. Effective gallbladder emptying (residual volume < or = 6 mL) and apolipoprotein E4 (apoE4) independently influenced gallstone recurrence. Recurrence rate was higher (log rank test, P = .037) in those patients who were homozygous and heterozygous for the E4 allele compared with the individuals who were not expressing the apoE4 allele. Accordingly, there was an overrepresentation of the allele frequency for E4 in the group with gallstone recurrence (P =.03). Patients with small postprandial residual gallbladder volumes (</= 6 mL) had a lower probability of stone recurrence than those with large residual gallbladder volumes (log rank test, P = .0215). Biliary pain was more frequent with recurrence (55% vs. 13%, P = .001). The present study indicates that apoE4 genotype is associated with increased speed of gallstone clearance as well as a high risk of recurrence after ESWL. This finding points to a possible role for genetic factors in the pathogenesis of cholesterol gallstones. Effective gallbladder emptying is important for speed of clearance and prevention of recurrence. Patients with initial solitary stones have a decreased early- but not long-term gallstone recurrence rate.

Adult↗
PubMed1996

Lipoprotein lipase gene mutations D9N and N291S in four pedigrees with familial combined hyperlipidaemia.

The role of the lipoprotein lipase (LPL) gene in familial combined hyperlipidaemia (FCH) is unclear at present. We screened a group of 28 probands with familial combined hyperlipidaemia and a group of 91 population controls for two LPL gene mutations, D9N and N291S. LPL-D9N was found in two probands and one normolipidaemic population control. LPL-N291S was found in four probands and four population controls. Subsequently, two pedigrees from probands with the D9N mutation and two pedigrees from probands with the N291S mutation were studied, representing a total of 24 subjects. Both LPL gene mutations were associated with a significant effect on plasma lipids and apolipoproteins. Presence of the D9N mutation (n = 7) was associated with hypertriglyceridaemia [2.69 +/- 1.43 (SD) mmol L-1] and reduced plasma high-density lipoprotein cholesterol (HDL-C) concentrations (0.92 +/- 0.21 mmol L-1) compared with 11 non-carriers (triglyceride 1.75 +/- 0.64 mmol L-1; HDL-C 1.23 +/- 0.30 mmol L-1, P = 0.03 and P = 0.025 respectively). LPL-D9N carriers had higher diastolic blood pressures than non-carriers. LPL-N291S carriers (n = 6) showed significantly higher (26%) apo B plasma concentrations (174 +/- 26 mg dL-1) than non-carriers (138 +/- 26 mg dL-1; P = 0.023), with normal post-heparin plasma LPL activities. Linkage analysis revealed no significant relationship between the D9N or N291S LPL gene mutations and the FCH phenotype (hypertriglyceridaemia, hypercholesterolaemia or increased apo B concentrations). It is concluded that the LPL gene did not represent the major single gene causing familial combined hyperlipidaemia in the four pedigrees studied, but that the LPL-D9N and LPL-N291S mutations had significant additional effects on lipid and apolipoprotein phenotype.

Adult↗
PubMed1996

Apolipoprotein A-I/C-III/A-IV gene cluster in familial combined hyperlipidemia: effects on LDL-cholesterol and apolipoproteins B and C-III.

The underlying genetic abnormalities in familial combined hyperlipidemia (FCH) have not been elucidated, although previous association and linkage studies have implicated the apoA-I/C-III/A-IV gene cluster. We now report studies of this cluster in 18 probands, 390 family members (hyperlipidemic relatives, n = 179; normolipidemic relatives, n = 211), and 177 spouses. Three restriction enzyme polymorphisms, XmnI and MspI sites 5' of the apoA-I gene and the SstI site in the 3' untranslated region of exon 4 of the apoC-III gene, were examined. In hyperlipidemic relatives and FCH probands, the frequency of each minor allele was significantly higher than in spouses. Associated with the higher frequency of minor alleles were elevated plasma cholesterol, triglycerides, LDL-cholesterol, apoB, and apoC-III levels. Quantitative sib-pair analysis revealed linkage between the MspI minor allele and plasma LDL cholesterol levels (P < 0.04). The present data indicate that, while apoA-I/C-III/A-IV gene cluster is not the primary cause of FCH, this cluster has a specific modifying effect on plasma triglyceride and LDL cholesterol levels.

Adult↗
PubMed1995

Apolipoprotein E2/E3/E4 genotyping with agarose gels.

Here we report an improved, simple method to assign the human apolipoprotein (apo) E genotype and its isoforms, apo E2, apo E3, and apo E4. Genomic DNA was amplified with specific primers that included the polymorphic region of amino acids 112 and 158. Digestion of the product with Hhal resulted in unique fragments that were separated on Meta-Phor agarose instead of polyacrylamide. The pattern of unique DNA fragments obtained unequivocally characterizes the different apo E alleles.

Apolipoprotein E2↗