J. Puzo

Comparison of genetic versus clinical diagnosis in familial hypercholesterolemia.

Early diagnosis is important in familial hypercholesterolemia (FH), a highly atherogenic condition, but internationally agreed clinical diagnostic criteria are lacking. Genetic testing for low-density lipoprotein (LDL) receptor (LDLR) and apolipoprotein B (APOB) gene defects is the preferable diagnostic method, but the best phenotype indication to proceed with genetic diagnosis has not been established. The aim of this study was to assess the predictive and accuracy values of standard diagnostic criteria for detecting disease-causing mutations in 825 subjects with clinical FH aged > or =14 years from 3 lipid clinics in Spain. All subjects underwent thorough genetic testing for the detection of LDLR and APOB defects using the Lipochip platform. FH-causing mutations were detected in 459 subjects (55.6%). By logistic regression analysis, familial or personal history of tendon xanthoma (TX) and LDL cholesterol were strongly associated with genetic diagnosis (p <0.005, R(2) = 0.41). In subjects without familial or personal histories of TX, the diagnostic criteria for FH of the Make Early Diagnosis to Prevent Early Deaths (MEDPED) project, based on age-specific LDL cholesterol thresholds, showed sensitivity of 72.4%, specificity of 71.1%, and accuracy of 71.6%. LDL cholesterol > or =190 mg/dl in subjects with familial or personal histories of TX and > or =220, > or =225, and > or =235 mg/dl in those without such histories aged <30, 30 to 39, and > or =40 years, respectively, showed sensitivity of 91.1%, specificity of 71.1%, and accuracy of 74.2% for a positive genetic diagnosis. This new set of diagnostic criteria for FH was validated in an independent group of 440 subjects from 6 additional Spanish lipid clinics. In conclusion, TX and age-adjusted LDL cholesterol cut-off values have the highest value for clinical diagnosis and indication of genetic testing in FH.

Serum Chitotriosidase Activity Is Increased in Subjects With Atherosclerosis Disease

Objective—This study was undertaken to analyze the relation between serum activity of chitotriosidase enzyme, a protein synthesized exclusively by activated macrophages, and atherosclerotic lesion extent in subjects with atherothrombotic stroke (ATS) and in subjects with ischemic heart disease (IHD). Methods and Results—We assayed the serum chitotriosidase activity and a common chitotriosidase gene polymorphism that causes deficiency in chitotriosidase activity in 3 Spanish populations, ATS (n=153), IHD (n=124), and control (n=148) subjects. Statistical differences were found in serum chitotriosidase activity between ATS (88.1±4.6 nmol/mL · h, P <0.0001) and IHD subjects (79.0±6.3, P =0.002) versus control group (70.9±5.2). These observed differences were not attributable to a distinct allelic or genotype distribution. The extension of the atherosclerotic lesion in carotids of ATS subjects was measured by duplex sonography. Chitotriosidase activities were 66.9±9.6, 88.7±8.3, and 107.7±11.8 for subjects with carotid stenosis ≤30%, 31% to 60%, and >60%, respectively. Statistical differences were observed between subjects with major and intermediate stenosis grade compared with subjects with minor stenosis, P =0.005 and P =0.016, respectively. Conclusions—Serum chitotriosidase activity is significantly increased in individuals suffering from atherosclerosis disease and is related to the severity of the atherosclerotic lesion, suggesting a possible role as atherosclerotic extent marker.

Apolipoprotein E gene mutations in subjects with mixed hyperlipidemia and a clinical diagnosis of familial combined hyperlipidemia.

OBJECTIVE Rare mutations in the APOE gene, undetectable with the usual genotyping technique, are responsible for dominant familial dysbetalipoproteinemia (FD) and therefore could be easily misclassified as familial combined hyperlipidemia (FCHL). We aimed to identify APOE mutations associated with dominant combined hyperlipoproteinemia and to establish their frequency in subjects with a clinical diagnosis of FCHL. METHODS AND RESULTS In 279 unrelated subjects with FCHL in whom a functional LDLR mutation was excluded, sequencing of the entire APOE gene detected 9 carriers of a rare mutation: 5 subjects (1.8%) with the R136S mutation (arginine at residue 136 changed to serine) and 4 subjects (1.4%) with the p.Leu149del mutation, a 3-bp inframe deletion that results in the loss of leucine at position 149. Both genetic defects were detected with similar frequency (2.5% and 1.3%, respectively) in an independent group of 160 FCHL subjects from other locations in Spain. Family studies demonstrated cosegregation of these APOE mutations with hyperlipoproteinemia. R136S carriers showed dysbetalipoproteinemia, while the lipid phenotype of p.Leu149del carriers was IIa or IIb. CONCLUSIONS Rare APOE mutations are responsible for approximately 3.5% of FCHL cases in our population. APOE R136S and p.Leu149del induce autosomal dominant FD and a phenotype indistinguishable from FCHL, respectively.

Hipercolesterolemia familiar heterocigota en España. Estudio descriptivo de 819 casos no relacionados

Fundamento La hipercolesterolemia familiar heterocigota (HFh) es un trastorno frecuente en lapoblacion general y la cardiopatia isquemica prematura, su complicacion mas importante. Elobjetivo de este estudio es describir las manifestaciones clinicas y las caracteristicas de la enfermedadcardiovascular en la HFh en Espana. Pacientes y metodo Analisis de una cohorte de 819 sujetos no relacionados entre si (449 mujeresy 370 varones), con diagnostico clinico de hipercolesterolemia familiar, procedentes de 69clinicas de lipidos. Se registraron los datos clinicos y analiticos, ademas de los antecedentespersonales y familiares de enfermedad cardiovascular. Resultados La concentracion de colesterol total (DE) en el momento del diagnostico fue de412 (87) mg/dl en las mujeres y de 400 (78) mg/dl en los varones (p Conclusion Las caracteristicas clinicas y la presencia de enfermedad cardiovascular en la HFhen Espana son similares a las descritas en otros paises. El cLDL, la edad, el sexo, el tabaquismo,la hipertension arterial y el indice de masa corporal son importantes predictores de la enfermedadcardiovascular.

Serum Chitotriosidase Activity, a Marker of Activated Macrophages, Predicts New Cardiovascular Events Independently of C-Reactive Protein

Background: C-reactive protein (CRP) is a well-established inflammation marker associated with cardiovascular risk. However, its relationship with chitotriosidase activity, a novel marker of activated macrophages highly expressed in human atherosclerotic plaques, is unknown. Therefore, we sought to determine if serum chitotriosidase activity predicts the risk of new coronary events, and to analyze its relationship with CRP. Methods: Chitotriosidase activity and genotype, and high-sensitivity CRP were measured at baseline in 133 middle-aged men with stable coronary heart disease, who were followed for the occurrence of cardiovascular morbidity and mortality for a mean of 4 years. We studied the value of these proteins in predicting the risk of new cardiovascular events. Results: Serum chitotriosidase activity was higher in the group of subjects with a prespecified major event (nonfatal myocardial infarction, nonfatal ischemic stroke, coronary revascularization procedures and death from cardiovascular causes) than in the group of subjects without event, 116 ± 30.9 nmol/ml·h versus 74.2 ± 5.69 nmol/ml·h, respectively (p = 0.042). The baseline values of chitotriosidase activity and CRP did not correlate (R = 0.104, p = 0.266), but both parameters were related to a reduction of event-free survival in the Cox regression analysis, with relative risks of 2.61 (p = 0.060) and 2.56 (p = 0.019), respectively. Chitotriosidase activity seems to be a better marker for new events occurring after 2 years of follow-up than in the first 2 years. Both markers had similar predictive values, and their sensitivity (64%) and negative predictive value (84%) were improved when combined. Conclusions: Our results suggest that serum chitotriosidase activity predicts the risk of new cardiovascular events in the following 4 years. This new cardiovascular risk marker is independent of CRP and, when combined, the prediction of the risk of new cardiovascular events and the identification of a lower risk group seem to improve.

Role of naturally-occurring plant sterols on intestinal cholesterol absorption and plasmatic levels

Cardiovascular disease is a major health problem in developed countries although its incidence is relatively lower in Mediterranean countries which is partly ascribed to dietary habits. Epidemiologic evidence shows that elevated serum cholesterol, specifically low-density lipoprotein cholesterol (c-LDL), increases cardiovascular disease. Phytosterols are bioactive compounds, found in all vegetable foods, which inhibit intestinal cholesterol absorption and, therefore, have a serum cholesterollowering effect. Intestinal cholesterol absorption is a multistep process where, plant sterols and stanols may act:a) attenuating the NPC1L1 gene expression, which may result in a lower cholesterol uptake from the lumen;b) lowering the cholesterol esterification rate by the ACAT2 (acyl-CoA cholesterol acyltransferase) and, consequently, the amount of cholesterol secreted via the chylomicrons andc) upregulating the expression of ABC-transporters ABCG5 and ABCG8 in intestinal cells, which may result in an increased excretion of cholesterol by the enterocyte back in the lumen. Many clinical trials proved that commercial products enriched with phytosterols reduce cholesterol levels. Likewise, recent studies show that phytosterols present in natural food matrices are also effective and could be an important component of cardioprotective dietary patterns such as the Mediterranean diet.ResumenLe enfermedad cardiovascular es un problema de salud importante en los países desarrollados, aunque su incidencia es relativamente menor en los países mediterráneos lo que es parcialmente atribuible a los hábitos dietéticos. Existen evidencias epidemiológicas que muestran que el colesterol sérico elevado, específicamente el colesterol ligado a las lipoproteínas de baja densidad (c-LDL), incrementa la enfermedad cardiovascular. Los fitosteroles son compuestos bioactivos, presentes en todos los alimentos de origen vegetal, que inhiben la absorción intestinal de colesterol y, por lo tanto, tienen un efecto reductor en el colesterol sérico. La absorción intestinal de colesterol es un proceso multi-etapa donde los esteroles y estanoles vegetales pueden actuar de diversas formas:a) atenuando la expresión del gen NPC1L1, lo que puede suponer una disminución del ingreso de colesterol desde el lumen intestinal;b) disminuyendo la tasa de esterificación del colesterol por la ACAT2 (acil-CoA colesterol aciltransferasa) y, en consecuencia, la cantidad de colesterol excretada vía quilomicrones yc) aumentando la expresión de los ABC-transportadores ABCG5 y ABCG8 en las células intestinales, lo que puede derivar en una excreción incrementada de colesterol desde el enterocito hacia el lumen. Diversos ensayos clínicos han demostrado que los productos comerciales enriquecidos con fitosteroles reducen los niveles de colesterol. Sin embargo, estudios recientes muestran que los fitosteroles presentes en matrices alimentarias naturales también pueden ser bioactivos y podrían ser un componente importante de los patrones dietéticos cardioprotectores como es la dieta Mediterránea.

A presumptive new locus for autosomal dominant hypercholesterolemia mapping to 8q24.22

Cenarro A, García‐Otín A‐L, Tejedor MT, Solanas M, Jarauta E, Junquera C, Ros E, Mozas P, Puzo J, Pocoví M, Civeira F. A presumptive new locus for autosomal dominant hypercholesterolemia mapping to 8q24.22.

Apolipoprotein E genotype is not associated with cardiovascular disease in heterozygous subjects with familial hypercholesterolemia

BACKGROUND Familial hypercholesterolemia (FH) is a genetic disorder characterized by high low-density lipoprotein cholesterol levels and premature cardiovascular disease (CVD). There are important differences in the presence of CVD among heterozygous subjects with FH. Some of this variability can be explained by genetic factors, and the apolipoprotein (apo) E genotype has been proposed as a useful marker. METHODS We analyzed the apo E genotype in 706 non-related subjects who were heterozygous for FH from Spain. CVD was present in 198 subjects (28%), 132 men (41%) and 66 women (17%). RESULTS Apo E allele frequencies for the epsilon 3, epsilon 4, and epsilon 2 alleles were 0.89, 0.09, and 0.02 respectively. Age, body mass index, smoking status, high blood pressure, diabetes mellitus, presence of tendon xanthomas, total cholesterol level, triglyceride levels, high-density lipoprotein cholesterol level, low-density lipoprotein cholesterol level, and Lp(a) did not differ among genotypes. The incidence of CVD and the age of onset of CVD did not differ among genotypes either. In the multivariant analysis, apo E genotype did not contribute significantly to CVD. CONCLUSIONS Heterozygous men with FH have a very high risk of coronary disease in a Mediterranean country, and the apo E genotype in this large group of adults with FH is not associated either with CVD or lipid values, in contrast with the established effect in the general population.

Naturally-occurring phytosterols in the usual diet influence cholesterol metabolism in healthy subjects

BACKGROUND AND AIMS Modulation of cholesterol absorption is potentially an effective way of lowering blood cholesterol levels and decreasing inherent cardiovascular risk in the general population. It is well established that cholesterol absorption efficiency can be modified by the intake of foods enriched with gram-doses of phytosterols, but little is known about the effects of phytosterols in the usual diet, even though moderate doses have been reported to affect whole-body cholesterol metabolism. A way to indirectly measure cholesterol synthesis and absorption rates is by quantification of serum non-cholesterol sterols. The aim of this study was to investigate the role of naturally occurring phytosterol intake on cholesterol absorption and serum cholesterol concentrations in a Spanish free-living population. METHODS AND RESULTS A total of 85 healthy volunteers were studied regarding their dietary habits (using a validated food frequency questionnaire), lipid profile and surrogate markers of cholesterol metabolism. Subjects were classified into tertiles of total phytosterol intake, and differences in lipid profile and markers of cholesterol metabolism were assessed by multivariate linear regression models adjusted for various confounders. The estimated daily intake of phytosterols and cholesterol was 489 (median) and 513 (mean) mg, respectively. Both serum low-density lipoprotein (LDL)-cholesterol concentration and sitosterol-to-cholesterol ratio adjusted by sitosterol intake (a surrogate marker of intestinal cholesterol absorption) decreased significantly (p < 0.05, both) across tertiles of phytosterol intake. CONCLUSION Moderate doses of phytosterols in the habitual diet might have a protective effect on the lipid profile via decreasing cholesterol absorption.

Comparison of the hypolipidemic effect of gemfibrozil versus simvastatin in patients with type III hyperlipoproteinemia

Abstract Background Type III hyperlipoproteinemia is characterized by the accumulation of chylomicron and very low density lipoprotein (VLDL) remnants. Individuals with this disorder have a high risk of premature atherosclerosis, and hypolipidemic drugs are useful in their management. Methods We compared, in a double-blind, placebo-controlled, randomized crossed study, the effects of gemfibrozil (1200 mg/day) and simvastatin (20 mg/day) on lipids, apolipoprotein AI, apolipoprotein B, and apolipoprotein E and on lipids and apolipoprotein B content in VLDL, intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) in 10 patients with type III hyperlipoproteinemia. Results Levels of total cholesterol, VLDL cholesterol, IDL cholesterol, and apolipoprotein B decreased with both drugs. Larger reductions in triglycerides (109 ± 28.2 mg/dL, P = .005), VLDL cholesterol (24.7 ± 10.9 mg/dL, P = .05), and VLDL triglycerides (86.3 ± 20.2 mg/dL, P = .003) were obtained with gemfibrozil compared with simvastatin. LDL cholesterol reduction was more effective with simvastatin than with gemfibrozil (44.3 ± 17.1 mg/dL, P = .03). HDL cholesterol after gemfibrozil was 5.71 ± 2.37 mg/dL higher than after simvastatin. Conclusions In patients with type III hyperlipoproteinemia gemfibrozil is more effective in reducing total triglyceride and VLDL lipid levels than simvastatin, and simvastatin is better in reducing LDL cholesterol than gemfibrozil is. IDL and apolipoprotein E levels were reduced similarly with both drugs. (Am Heart J 1999;138:156-62.)