Miguel Pocovi

Association of Polymorphisms at the SR-BI Gene Locus With Plasma Lipid Levels and Body Mass Index in a White Population

The scavenger receptor class B type I (SR-BI) is a lipoprotein receptor that has been shown to be important in high density lipoprotein cholesterol (HDL-C) metabolism in mice. To determine its role in humans, we have characterized the human SR-BI gene and investigated its genetic variation in 489 white men and women. Five variants were demonstrated: 2 in introns (3 and 5) and 3 in exons (1, 8, and 11). Three variants at exons 1 and 8 and intron 5 with allele frequencies >0.1 were used to examine associations with lipid or anthropometric variables. The exon 1 variant was significantly (P<0.05) associated with increased HDL-C and lower low density lipoprotein cholesterol (LDL-C) values in men, but no associations were observed in women. The exon 8 variant was associated in women with lower LDL-C concentrations (3.05+/-0.98 mmol/L and 3.00+/-0.93 mmol/L for heterozygotes and homozygotes, respectively) compared with women homozygous for the common allele (3.39+/-1.09 mmol/L, P=0. 043). No associations for this variant were observed in men. Women carriers of the intron 5 variant showed a higher body mass index (23. 8+/-3.8 kg/m2, P=0.031) than those women homozygous for the common allele (22.4+/-3.4 kg/m2). Similar results were observed after haplotype analysis. Multiple regression analysis using HDL-C, LDL-C, and body mass index as dependent variables and age, sex, and each of the genetic variants as predictors also provided similar results. The associations found with both LDL-C and HDL-C suggest that SR-BI may play a role in the metabolism of both lipoprotein classes in humans.

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.

Pediatric non-neuronopathic Gaucher disease: presentation, diagnosis and assessment. Consensus statements

Gaucher disease is caused by defective activity of glucocerebrosidase. The resulting accumulation of glucocerebroside in the lysosomes of visceral macrophages in various tissue and organ compartments leads to multiple manifestations, including hepatosplenomegaly, anemia, thrombocytopenia, growth retardation and skeletal disease. The most prevalent form of Gaucher disease is the non-neuronopathic (type 1) variant, which lacks primary involvement of the central nervous system. Traditionally, this has been referred to as the ‘adult type’; however, 66% of individuals with symptomatic non-neuronopathic Gaucher disease manifest in childhood. Onset in childhood is usually predictive of a severe, rapidly progressive phenotype and children with non-neuronopathic Gaucher disease are at high risk for morbid complications. Enzyme therapy with recombinant human glucocerebrosidase in childhood can restore health in reversible manifestations and prevent the development of irreversible symptoms. A heightened focus on pediatric Gaucher disease is therefore needed. Although some correlation has been found between genotype and phenotype, mutation analysis is of limited value in disease prognosis. Management of pediatric Gaucher disease should be underpinned by a thorough assessment of the phenotype at baseline with regular monitoring thereafter. Excluding neuronopathic disease is recommended as the first step. Subsequently, baseline evaluation should focus on staging of different storage tissues, particularly the bone the involvement of which results in the greatest long-term morbidity. These organ assessments are recommended because bone disease severity may not correlate with disease severity in other organs and vice versa. In addition, different organs may respond differently to therapy. Initial assessment of each organ system can enable setting of realistic and individualized goals. Conclusion: A thorough approach to baseline assessment will improve the understanding of childhood Gaucher disease, optimizing management to minimize impairment of growth and development and prevent irreversible symptoms.

Clinical experience with miglustat therapy in pediatric patients with Niemann-Pick disease type C: A case series

Niemann-Pick disease type C (NP-C) is an inherited neurovisceral lysosomal lipid storage disease characterized by progressive neurological deterioration. Different clinical forms have been defined based on patient age at onset: perinatal, early-infantile (EI), late-infantile (Li), juvenile and adult. We evaluated the efficacy and tolerability of miglustat in 16 symptomatic NP-C patients, with comparative reference to one neurologically asymptomatic, untreated patient. All patients were categorized according to age at neurological disease onset, and were assessed using a standardized clinical assessment protocol: disability and cognitive function scales, positron emission tomography (PET), and biochemical markers. PET and disability scale evaluations indicated that cerebral hypometabolism and neurological symptoms were stabilized during treatment in juvenile-onset NP-C patients. EI and Li NP-C patients, who had higher disease severity at baseline (treatment start), showed increased disability scores and progressive cerebral hypometabolism during follow up. Similarly, while cognitive scale scores remained relatively stable in patients with juvenile NP-C, cognition deteriorated in EI and Li patients. Plasma chitotriosidase (ChT) activity was lower in the juvenile NP-C subgroup than in EI and Li patients, and generally increased in patients who discontinued treatment. Plasma CCL18/PARC and ChT activities indicated greater macrophagic activity in EI and Li patients versus juveniles. Miglustat was generally well tolerated; frequent adverse events included diarrhea and flatulence, which were managed effectively by dietary modification and loperamide. Overall, miglustat appeared to stabilize neurological status in juvenile-onset NP-C patients, but therapeutic benefits appeared smaller among younger patients who were at a more advanced stage of disease at baseline.

LDLR Database (second edition): New additions to the database and the software, and results of the first molecular analysis

Mutations in the LDL receptor gene (LDLR) cause familial hypercholesterolemia (FH), a common autosomal dominant disorder. The LDLR database is a computerized tool that has been developed to provide tools to analyse the numerous mutations that have been identified in the LDLR gene. The second version of the LDLR database contains 140 new entries and the software has been modified to accommodate four new routines. The analysis of the updated data (350 mutations) gives the following informations: (i) 63% of the mutations are missense, and only 20% occur in CpG dinucleotides; (ii) although the mutations are widely distributed throughout the gene, there is an excess of mutations in exons 4 and 9, and a deficit in exons 13 and 15; (iii) the analysis of the distribution of mutations located within the ligand-binding domain shows that 74% of the mutations in this domain affect a conserved amino-acid, and that they are mostly confined in the C-terminal region of the repeats. Conversely, the same analysis in the EGF-like domain shows that 64% of the mutations in this domain affect a non-conserved amino-acid, and, that they are mostly confined in the N-terminal half of the repeats. The database is now accessible on the World Wide Web at http://www.umd.necker.fr

Usefulness of Triglycerides-to–High-Density Lipoprotein Cholesterol Ratio for Predicting the First Coronary Event in Men

Overweight and obesity potentiate the development of cardiovascular risk factors but many doubts have arisen recently regarding their role in coronary events. We evaluated the predictive value of a surrogate maker of insulin resistance, the ratio of triglyceride (TG) to high-density lipoprotein (HDL), for the incidence of a first coronary event in men workers according to body mass index (BMI). We designed a case-control study of active subjects collected from a single factory through their annual health examination and medical reports. Case subjects included those with myocardial infarction, unstable angina pectoris, or subclinical myocardial ischemia detected through electrocardiographic abnormalities. The sample was constituted by 208 case and 2,080 control subjects (mean age 49.9 years, 49.6 to 50.2). General characteristics of case and control subjects were well matched. The TG/HDL ratio was significantly higher in case subjects compared to controls. Stratification of the sample revealed an increasing prevalence of case subjects and mean TG/HDL in each category of BMI. Multivariable analysis, adjusted by smoking, demonstrated that TG/HDL increased 50% the risk of a first coronary event (odds ratio [OR] 1.47, 95% confidence interval [CI] 1.26 to 1.71), whereas low-density lipoprotein cholesterol values indicated a more moderate increased risk (OR 1.01, 95% CI 1.005 to 1.012); metabolic syndrome (OR 1.76, 95% CI 0.94 to 3.30) and hypertension (OR 1.50, 95% CI 0.81 to 2.79) did not reach statistical significance. The TG/HDL ratio was associated with a first coronary event in all categories of BMI. In conclusion, the TG/HDL ratio has a high predictive value of a first coronary event regardless of BMI.

Force majeure: therapeutic measures in response to restricted supply of imiglucerase (Cerezyme) for patients with Gaucher disease.

Gaucher disease is the first lysosomal disorder for which clinically effective enzyme replacement therapy has been introduced. Lifelong treatment with imiglucerase, the recombinant glucocerebrosidase manufactured by the Genzyme Corporation (MA, USA), is administered intravenously - usually at biweekly intervals. An acute shortage of imiglucerase (to 20% of prior global supply) has occurred as a result of viral contamination of the production facility; production was halted, and a full supply of imiglucerase is not anticipated until January 2010. An urgent meeting of physicians, researchers, and patients was convened through the agency of the European Working Group for Gaucher Disease; this was instigated by patients internationally represented by the European Gaucher Alliance. Here we present a position statement based on the findings of the group, with key recommendations about identification and monitoring of at-risk patients threatened by the abrupt withdrawal of treatment, the equitable distribution of residual imiglucerase - and access to alternative treatments including those that have completed phase III clinical trials but have not yet been licensed.

Tendon Xanthomas in Familial Hypercholesterolemia Are Associated With Cardiovascular Risk Independently of the Low-Density Lipoprotein Receptor Gene Mutation

Objective—To investigate the significance of tendon xanthomas (TX) in heterozygous subjects with familial hypercholesterolemia (hFH). Methods and Results—951 men and women with genetic diagnosis of hFH were studied, of whom 278 (29.2%) presented TX. TX frequency increased with age from 6.9% in subjects 20 to 30 years to 38.3% at 51 to 60 years, with a decrease in those older than 60 years. Total and low-density lipoprotein (LDL) cholesterol were higher in TX+ than in TX− subjects (439.0±78.5 mg/dL and 363.1±76.5 mg/dL versus 400.6±73.4 and 323.3±71.0, respectively; P=0.001). High-density lipoprotein (HDL) cholesterol was lower in TX+ than in TX− subjects (50.4±15.0 mg/dL versus 53.1±14.8 mg/dL; P=0.005). Lp(a), apolipoprotein E genotype, and type of LDL receptor gene mutation showed no differences between groups. 102 TX+ reported premature cardiovascular disease (CVD) (36.7%) versus 93 TX− (13.8%) (P=0.001). The relative odds for premature CVD were higher in women (4.49 versus 2.26), and increased in hFH younger than 51 years to 3.60 (95% CI, 1.703 to 7.608) in men and to 17.1 (95% CI, 2.697 to 108.920) in women. In the multivariate analysis, age, male sex, LDL cholesterol, and hypertension showed significant positive association with TX, whereas body mass index showed negative association with TX. Conclusions—TX are associated with cardiovascular risk factors and higher CVD, indicating that their detection indicates the need for more aggressive lipid-lowering intervention.

Human apolipoprotein A-I gene promoter mutation influences plasma low density lipoprotein cholesterol response to dietary fat saturation

Previous studies have shown that the A to G transition occurring at position -75 bp upstream of the transcriptional start site in the human apolipoprotein A-I gene may affect plasma high density lipoprotein cholesterol (HDL-C) levels and low density lipoprotein cholesterol (LDL-C) response to changes in amount of dietary fat. We have examined the response to dietary fat saturation as a function of this mutation in 50 men and women. Subjects were first fed a saturated (SAT) fat diet (35% fat, 17% SAT) for 28 days, followed by a diet rich in monounsaturated fatty (MUFA) acids (35% fat, 22% MUFA) for 35 days and a diet rich in polyunsaturated (PUFA) fat (35% fat, 13% PUFA) for 35 days. All meals were prepared and consumed at the study sites. Lipoproteins were measured at the end of each diet period. The allele frequency for the A allele was 0.13. Subjects carrying the A allele had higher plasma cholesterol, LDL-C and triglyceride levels than those homozygotes for the G allele. As compared to the SAT diet, a PUFA diet induced significantly greater plasma total (P = 0.003) and LDL-C decreases (P = 0.001) in G/A women (-1.62 and -1.32 mmol/l, respectively) than in G/G subjects (-0.87 and -0.74 mmol/l for plasma and LDL-C, respectively). Multiple regression analysis demonstrated that in women, the variability in LDL-C response from a diet rich in SAT fat to a diet rich in PUFA was primarily due to LDL-C levels (during the SAT phase), accounting for 55.1% of the variance, waist to hip ratio (W/H; 11.4%) and the G/A polymorphism (10%). Whereas in men the major determinant of this response was smoking (21.4%). In conclusion, the G/A polymorphism appears to have a small but significant effect on plasma LDL-C responsiveness to changes in dietary fat saturation specially in women.