Background-Several studies have reported that the cholesteryl ester transfer protein (CETP) TaqIB gene polymorphism is associated with HDL cholesterol (HDL-C) levels and the risk of coronary artery disease (CAD), but the results are inconsistent. In addition, an interaction has been implicated between this genetic variant and pravastatin treatment, but this has not been confirmed. Methods and Results-A meta-analysis was performed on individual patient data from 7 large, population-based studies (each Ͼ500 individuals) and 3 randomized, placebo-controlled, pravastatin trials. Linear and logistic regression models were used to assess the relation between TaqIB genotype and HDL-C levels and CAD risk. After adjustment for study, age, sex, smoking, body mass index (BMI), diabetes, LDL-C, use of alcohol, and prevalence of CAD, TaqIB genotype exhibited a highly significant association with HDL-C levels, such that B2B2 individuals had 0.11 mmol/L (0.10 to 0.12, PϽ0.0001) higher HDL-C levels than did B1B1 individuals. Second, after adjustment for study, sex, age, smoking, BMI, diabetes, systolic blood pressure, LDL-C, and use of alcohol, TaqIB genotype was significantly associated with the risk of CAD (odds ratioϭ0.78 [0.66 to 0.93]) in B2B2 individuals compared with B1B1 individuals (P for linearityϭ0.008). Additional adjustment for HDL-C levels rendered a loss of statistical significance (Pϭ0.4). Last, no pharmacogenetic interaction between TaqIB genotype and pravastatin treatment could be demonstrated. Conclusions-The CETP TaqIB variant is firmly associated with HDL-C plasma levels and as a result, with the risk of CAD. Importantly, this CETP variant does not influence the response to pravastatin therapy. (Circulation. 2005;111: 278-287.)

LTHOUGH MYOCARDIAL INfarction (MI) and atherothrombotic ischemic stroke are thought to be caused by rupture of vulnerable atherosclerotic plaques, 1 they are recognized to be complex disorders that likely result from multifaceted interactions between an in

Objective-Angiopoietin-like 3 (Angptl3) is a regulator of lipoprotein metabolism at least by inhibiting lipoprotein lipase activity. Loss-of-function mutations in ANGPTL3 cause familial combined hypolipidemia through an unknown mechanism. Approach and Results-We compared lipolytic activities, lipoprotein composition, and other lipid-related enzyme/lipid transfer proteins in carriers of the S17X loss-of-function mutation in ANGPTL3 and in age-and sex-matched noncarrier controls. Gel filtration analysis revealed a severely disturbed lipoprotein profile and a reduction in size and triglyceride content of very low density lipoprotein in homozygotes as compared with heterozygotes and noncarriers. S17X homozygotes had significantly higher lipoprotein lipase activity and mass in postheparin plasma, whereas heterozygotes showed no difference in these parameters when compared with noncarriers. No changes in hepatic lipase, endothelial lipase, paraoxonase 1, phospholipid transfer protein, and cholesterol ester transfer protein activities were associated with the S17X mutation. Plasma free fatty acid, insulin, glucose, and homeostatic model assessment of insulin resistance were significantly lower in homozygous subjects compared with heterozygotes and noncarriers subjects. Conclusions-These results indicate that, although partial Angptl3 deficiency did not affect the activities of lipolytic enzymes, the complete absence of Angptl3 results in an increased lipoprotein lipase activity and mass and low circulating free fatty acid levels. This latter effect is probably because of decreased mobilization of free fatty acid from fat stores in human adipose tissue and may result in reduced hepatic very low density lipoprotein synthesis and secretion via attenuated hepatic free fatty acid supply. Altogether, Angptl3 may affect insulin sensitivity and play a role in modulating both lipid and glucose metabolism. Key Words: ANGPTL3 protein, human ◼ ANGPTL4 protein, human ◼ endothelial lipase, human ◼ familial combined hypolipidemia ◼ fatty acids, nonesterified ◼ hepatic lipase, human ◼ lipoprotein lipase

Familial combined hypolipidemia segregates as a recessive trait so that apolipoprotein B- and apolipoprotein A-I-containing lipoproteins are comprehensively affected only by the total deficiency of Angptl3. Familial combined hypolipidemia does not perturb whole-body cholesterol homeostasis and is not associated with adverse clinical sequelae.

Abstract-Serum paraoxonase (PON) is an HDL-bound enzyme protecting LDL from oxidation. A common polymorphism of the paraoxonase gene (PON1) involving a Gln-to-Arg interchange at position 192 has been demonstrated to modulate PON activity toward paraoxon, a nonphysiological substrate; Arg192 (allele B) is associated with higher activity than Gln192 (allele A). This polymorphism has been proposed as a genetic marker of risk for coronary artery disease (CAD). However, the relationships between codon 192 PON1 genotypes, coronary atherosclerosis, and the occurrence of myocardial infarction (MI) are still controversial. PON1 genotypes were determined in 472 consecutive subjects (Ͼ40 years old) who underwent coronary angiography. CAD (Ͼ50% stenosis) was detected in 310 subjects (CADϩ); 162 subjects with Ͻ10% stenosis served as controls (CADϪ). We also evaluated 204 randomly selected individuals as population controls. PON1 genotypes were determined by PCR and AlwI restriction enzyme digestion. Frequencies of alleles A and B were 0.70 and 0.30 in angiographically assessed subjects and 0.73 and 0.27 in population controls, respectively ( 2 ϭ2.0; PϽ0.3). Distribution of PON1 genotypes in CADϩ were not significantly different from those in CADϪ ( 2 ϭ2.10; PϽ0.3). Similarly, no differences were observed in the subgroup of CADϩ with MI nor in that at higher oxidative risk (smokers and/or diabetics). After controlling for other coronary risk factors, no association was found between PON1 alleles and the presence of CAD. PON1 AA genotype was associated with reduced concentration of apolipoprotein B-containing triglyceride-rich lipoproteins. This study did not provide evidence of a significant association between codon 192 PON1 genotypes and coronary atherosclerosis in Italian patients. However, it did confirm that the PON1 low-activity allele is associated with a less atherogenic lipid profile. (Arterioscler Thromb

Objective-To better understand the role of lecithin:cholesterol acyltransferase (LCAT) in lipoprotein metabolism through the genetic and biochemical characterization of families carrying mutations in the LCAT gene. Methods and Results-Thirteen families carrying 17 different mutations in the LCAT gene were identified by Lipid Clinics and Departments of Nephrology throughout Italy. DNA analysis of 82 family members identified 15 carriers of 2 mutant LCAT alleles, 11 with familial LCAT deficiency (FLD) and 4 with fish-eye disease (FED). Forty-four individuals carried 1 mutant LCAT allele, and 23 had a normal genotype. Plasma unesterified cholesterol, unesterified/total cholesterol ratio, triglycerides, very-low-density lipoprotein cholesterol, and pre-␤ high-density lipoprotein (LDL) were elevated, and high-density lipoprotein (HDL) cholesterol, apolipoprotein A-I, apolipoprotein A-II, apolipoprotein B, LpA-I, LpA-I:A-II, cholesterol esterification rate, LCAT activity and concentration, and LDL and HDL 3 particle size were reduced in a gene-dose-dependent manner in carriers of mutant LCAT alleles. No differences were found in the lipid/lipoprotein profile of FLD and FED cases, except for higher plasma unesterified cholesterol and unesterified/total cholesterol ratio in the former. Conclusion-In a large series of subjects carrying mutations in the LCAT gene, the inheritance of a mutated LCAT genotype causes a gene-dose-dependent alteration in the plasma lipid/lipoprotein profile, which is remarkably similar between subjects classified as FLD or FED. Key Words: familial lecithin:cholesterol acyltransferase deficiency Ⅲ fish eye disease Ⅲ high-density lipoproteins Ⅲ lecithin:cholesterol acyltransferase Ⅲ mutation T he lecithin:cholesterol acyltransferase (LCAT) (phosphatidylcholine:sterol-O-acyltransferase; EC 2.3.1.43) enzyme is responsible for the synthesis of cholesteryl esters (CE) in plasma. 1 Through this action, LCAT plays a central role in the formation and maturation of high-density lipoproteins (HDL), and in the intravascular stage of reverse cholesterol transport, the major mechanism by which HDL modulate the development and progression of atherosclerosis. A defect in LCAT function would be expected to enhance atherosclerosis by interfering with this process.The human LCAT gene encompasses 4.2 kilobases and is localized in the q21-22 region of chromosome 16. Methods SubjectsProbands with primary hypoalphalipoproteinemia (HALP), defined by a plasma HDL-C level below the fifth percentile for the age-and sex-matched general population, were identified by Lipid Clinics and Departments of Nephrology throughout Italy. Plasma samples were analyzed for total and unesterified cholesterol; in 18 unrelated index cases, the results were suggestive of a defect in the LCAT gene. Genetic analysis revealed that 13 of 18 index cases carried at least 1 mutant LCAT allele. Relatives of the 13 probands were invited to participate in the study. All subjects gave an informed consent. Blood samples were collected after an overni...

Abstract-Insulin resistance is associated with increased risk of atherosclerosis. Insulin receptor substrate-1 (IRS-1) plays a key role in tissue insulin sensitivity. A common mutation (G972R) of the IRS-1 gene has been shown to impair IRS-1 function, and it has been associated with reduced insulin sensitivity and lipid abnormalities. This led us to investigate the role of the G972R mutation in predisposing individuals to coronary artery disease (CAD). The DNA of 318 subjects with angiographically documented coronary atherosclerosis (Ͼ50% stenosis) and 208 population control subjects was analyzed for the presence of the G972R mutation. This mutation was detected by nested polymerase chain reaction and BstNI restriction enzyme digestion. The frequency of the G972R mutation was significantly higher among patients with CAD than controls (18.9% versus 6.8%, respectively; PϽ0.001). After controlling for other coronary risk factors, the relative risk of CAD associated with the G972R mutation was 2. 001).The IRS-1 gene variant was associated with a higher frequency of diabetes mellitus (14.9% among carriers versus 6.5% among noncarriers; PϽ0.01) and with a 60% increase of plasma total triglycerides (PϽ0.001). Also, plasma concentrations of total cholesterol and the ratio of total cholesterol to HDL cholesterol were significantly (PϽ0.001) higher among carriers than noncarriers, although to lesser a extent. These effects were independent of CAD status. The G972R mutation in the IRS-1 gene was found to be a significant independent predictor of CAD. Moreover, this mutation greatly increased the risk of CAD in obese subjects and in patients with the cluster of abnormalities of insulin resistance syndrome. Besides the increased frequency of diabetes, carriers showed a more atherogenic lipid profile, suggesting a potential role of the IRS-1 gene in the pathogenesis of lipid abnormalities associated with CAD. (Arterioscler Thromb

NAFLD is a polygenic condition but the individual and cumulative contribution of identified genes remains to be established. To get additional insight into the genetic architecture of NAFLD, GWAS-identified GCKR, PPP1R3B, NCAN, LYPLAL1 and TM6SF2 genes were resequenced by next generation sequencing in a cohort of 218 NAFLD subjects and 227 controls, where PNPLA3 rs738409 and MBOAT7 rs641738 genotypes were also obtained. A total of 168 sequence variants were detected and 47 were annotated as functional. When all functional variants within each gene were considered, only those in TM6SF2 accumulate in NAFLD subjects compared to controls (P = 0.04). Among individual variants, rs1260326 in GCKR and rs641738 in MBOAT7 (recessive), rs58542926 in TM6SF2 and rs738409 in PNPLA3 (dominant) emerged as associated to NAFLD, with PNPLA3 rs738409 being the strongest predictor (OR 3.12, 95% CI, 1.8-5.5, P < 0.001). A 4-SNPs weighted genetic risk score value >0.28 was associated with a 3-fold increased risk of NAFLD. Interestingly, rs61756425 in PPP1R3B and rs641738 in MBOAT7 genes were predictors of NAFLD severity. Overall, TM6SF2, GCKR, PNPLA3 and MBOAT7 were confirmed to be associated with NAFLD and a score based on these genes was highly predictive of this condition. In addition, PPP1R3B and MBOAT7 might influence NAFLD severity.