Sergio Castillo

Cardiovascular disease in familial hypercholesterolaemia : Influence of low-density lipoprotein receptor mutation type and classic risk factors

AIM To determine the effect of the type of mutation in low-density lipoprotein receptor gene and the risk factors associated with the development of premature cardiovascular disease (PCVD) in a large cohort of heterozygous familial hypercholesterolemia (hFH) subjects with genetic diagnosis in Spain. METHODS AND RESULTS A cross-sectional study was conducted on 811 non-related FH patients (mean age 47.1+/-14 years, 383 males and 428 females) with a molecular defect in the low-density lipoprotein receptor (LDLR) gene from the Spanish National FH Register. Prevalence of PCVD was 21.9% (30.2% in males and 14.5% in women, P<0.001). Mean age of onset of cardiovascular event was 42.1 years in males and 50.8 years in females. Of those patients with PCVD, 59.5% of males and 27% of females suffered a second cardiovascular (CV) event. In multivariate analysis male gender, age, tobacco consumption (ever), and total cholesterol/HDL-cholesterol (TC/HDL-C) ratio were significantly associated with PCVD. Two hundred and twenty different mutations were found with a large heterogeneity. Patients carrying null-mutations had significantly higher frequency of PCVD and recurrence of CV events. No relationship with Lp(a) levels and genotype of Apo E were found. CONCLUSIONS This study confirms the importance of identifying some classic risk factors such as smoking and TC/HDL-C ratio, and also the type of mutation in LDLR gene in order to implement early detection and intensive treatment for the prevention of cardiovascular disease in FH patients.

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.

Genetic diagnosis of familial hypercholesterolemia using a DNA-array based platform

OBJECTIVES The aim of this study was to validate the Lipochip genetic diagnostic platform by assessing effectiveness, sensitivity, specificity and costs for the identification of patients with familial hypercholesterolemia (FH) in Spain. This platform includes the use of a DNA micro array, the detection of large gene rearrangements and the complete resequencing of the low-density lipoprotein receptor gene. DESIGN AND METHODS DNA samples of patients with clinically diagnosed FH were analyzed for mutations by application of the Lipochip platform. Results obtained were confirmed by DNA sequencing and MLPA analysis by two other, independent laboratories. RESULTS Of 808 patients tested, Lipochip detected a mutation in 66% of the cases and of these 78% were detected by the micro array. A specificity of 99.5% at a sensitivity of 99.8% was reached. A positive test result could be reported within 22 days after start of analysis. The total average screening costs of

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

350 per case were significantly lower compared to other existing screening programs. CONCLUSION Lipochip provides a reliable, fast and cheap alternative for the genetic testing of patients with clinically diagnosed FH.

Mutation analysis in 36 unrelated Spanish subjects with familial hypercholesterolemia: identification of 3 novel mutations in the LDL receptor gene.

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.

The apolipoprotein B R3500Q gene mutation in Spanish subjects with a clinical diagnosis of familial hypercholesterolemia

We used the single strand conformation polymorphism (SSCP) method to investigate 36 apparently unrelated Spanish patients with familial hypercholesterolemia (FH) for mutations in the promoter region and the 18 exons and their flanking intron sequences of the low density lipoprotein receptor (LDLR) gene. Nineteen aberrant SSCP patterns were found, and the underlying mutations were characterized by DNA sequencing. In addition, we tested all patients for the presence of mutations in the gene coding for apolipoprotein B (apo B). Five missense mutations (Q71E, S156L, E256K, N543H and T705I), four nonsense mutations (W(‐18)X, E10X, Q133X and C255X), six frameshift mutations (211delG, 518delG, 1045delC, 2085del19, 2207insT and 2393del9) and five splicing mutations (313+1G‐>C, 1061‐8T‐>C, 1845+1G‐>C, 2140+5G‐>A and 2390‐1G‐>C) were identified in the LDLR gene. In total, we detected 20 mutations, 3 of which, designated 1045delC, 1845+1G‐>C and 2207insT, have not been previously described. Seven patients were found to carry two different mutations in the same allele: W(‐18)X and E256K (one patient), Q71E and 313+1G‐>C (two patients), 1061‐8T‐>C and T705I (two patients), 518delG and 2140+5G‐>A (one patient) and N543H and 2393del9 (one patient). As we expected, there is a broad spectrum of mutations in the LDLR gene, given the genetic heterogeneity of the Spanish population. Hum Mutat 15:483–484, 2000.

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

Familial hypercholesterolemia (FH) and familial defective apolipoprotein B-100 (FDB) are autosomal codominant diseases characterized by elevated LDL cholesterol levels and premature coronary artery disease. Mutations of the LDL-receptor and apolipoprotein B genes, which affect the binding domains of their protein products, are the causal defects. Securing the diagnosis of these conditions by molecular assays is important because it mandates early intervention for coronary risk reduction. DNA screening for apolipoprotein B R3500Q gene mutation was performed in 913 unrelated Spanish individuals with a clinical diagnosis of FH using a modified polymerase chain reaction protocol and restriction enzyme genotyping. Thirteen FDB heterozygotes were identified (frequency of 1.4% in subjects with a clinical diagnosis of FH). The prevalence of hypercholesterolemic subjects with FDB in the general Spanish population was estimated to be as low as 2.8 x 10(-5) (95% CI, -3.1 x 10(-4) to 3.7 x 10(-4)). The ancestors of 11 out of 13 FDB carriers were from Galicia, a region of Celtic ancestry in Northwestern Spain. As the series included 100 unrelated subjects of Galician ancestry, FDB appears to be an important genetic cause of hypercholesterolemia in this region. All the R3500Q mutations were found on the same allele, assigned to haplotype XbaI-/MspI+/EcoRI-/3HVR48, suggesting that the mutant alleles are identical by descent in people from Spain, as observed in other Caucasian populations. In conclusion, the R3500Q mutation of the apolipoprotein B gene, a common cause of FH in central Europe, is infrequent in the general Spanish population, but it is common in Galicia.

MEDPED and the Spanish Familial Hypercholesterolemia Foundation.

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.

Screening of APOB Gene Mutations in Subjects with Clinical Diagnosis of Familial Hypercholesterolemia

We analysed clinical and genetic data of 819 non-related familial hypercholesterolemia patients. No differences on baseline low density lipoprotein (LDL) cholesterol levels between females and males were observed. High density lipoprotein (HDL) cholesterol values were higher in females than in males (57+/-15 vs. 47.7+/-13, respectively, P<0.01). Premature cardiovascular disease was present in 21.7% of cases (30.8% in males and 14.3% in females, P<0.001). A significant and positive correlation was observed between cardiovascular disease and age, gender, tobacco, total and LDL cholesterol levels at diagnosis, and negatively with HDL cholesterol levels. Analysis of LDL-receptor gene have been performed in 350 cases and 86 different mutations have been found.

Additional value of screening for minor genes and copy number variants in hypertrophic cardiomyopathy

Monogenic hypercholesterolemia is a group of lipid disorders, most of which have autosomal dominant transmission. Familial defective apoB (FDB) resulting from mutations in the APOB gene is a well-recognized cause of autosomal dominant monogenic hypercholesterolemia (ADMH). However, the frequency of FDB among patients with ADMH is not well established. The aim of our research was to screen for mutations responsible for FDB in subjects with a clinical diagnosis of familial hypercholesterolemia. We studied 408 patients from the Spanish Register of Familial Hypercholesterolemia, proportionally distributed among all Spanish regions. Abnormal SSCP patterns of the APOB gene were checked by DNA sequencing and restriction analysis. Three out of the 408 patients were carriers of the R3500Q mutation, and 2 subjects were carriers of the silent T3552T mutation; in both of these patients functional mutations in the LDL receptor gene were found. We conclude that FDB is not a common cause of ADMH in Spain; the R3500Q mutation is the only mutation in APOB causing FDB, and the LDL receptor binding domain of APOB is highly conserved in the studied sample.