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Familial hypercholesterolemia (FH) manifested as atherosclerosis is a major cause of coronary heart disease. Different scoring systems based on clinical and paraclinical data are currently used, but the FH diagnosis should be made only in the presence of the causative genetic defect. In the present study, 12 symptomatic (previously diagnosed with atherosclerosis) and asymptomatic family members were investigated. Serum lipids were measured using commercial reagents. A genetic investigation was performed by Sanger sequencing using commercial reagents and custom primers, while copy number variations and a selected set of 40 point mutations were evaluated using in vitro diagnostic medical devices. For the investigated patients, serum lipids were within the reference range, due to the fact that the subjects were following lipid-lowering therapy, and smoking was the only identifiable additional risk factor. Four benign exon variants and three intron variants situated within the low-density lipoprotein cholesterol receptor gene were identified by Sanger sequencing. No copy number variations and none of the 40 investigated point mutations were determined. Although independently considered benign, the combined effect of the identified genetic conditions could be pathogenic under the influence of additional risk factors. Even in the presence of a diagnosis made using clinical scores, the molecular diagnosis is often challenging, attesting to the complexity of FH genetic etiology.

Introduction: Patients with loss of function (LoF) mutations of the LDL receptor gene (LDLR) have lifelong elevations in LDL-C. We investigated their risk of cardiovascular (CV) events compared with patients with intact LDLR function. Methods: We performed a prospective genetic cohort analysis from the FOURIER trial including all 14,297 patients who consented for genetic testing, passed QC, and were of European ancestry. All patients had established ASCVD and were on moderate or high intensity statin therapy. Whole exome sequencing was performed and LoF mutations in LDLR were identified using LOFTEE, a tool for detecting protein-truncating variants. Polygenic risk for CAD was also calculated for each patient using a previously validated 27-SNP genetic risk score, with high and low risk defined as above and below the median. The primary endpoint was a composite of CV death, myocardial infarction, stroke, unstable angina, or coronary revascularization. Results: There were 111 (0.8%) patients identified with an LDLR LoF mutation, representing an approximately 4-fold enrichment compared to the general population. These patients had mean baseline LDL-C levels 62 mg/dl higher than those without an identified LDLR LoF mutation (160 vs. 98 mg/dl, pFigure, a ). When polygenic risk for CAD was combined with LDLR mutation status there was a significant gradient of risk identified (p-trend=0.001). Patients without a monogenic LDLR mutation or high polygenic risk had a 2.5-year KM event rate of 8.6%; those with either one had a 10.0-12.9% event rate; those with both had a 17.1% event rate ( Figure, b ). Conclusion: ASCVD patients with LDLR LoF mutations have persistently elevated LDL-C and increased CV risk despite intensive statin therapy. The combination of a monogenic LDLR mutation with high polygenic risk for CAD appears additive in this secondary prevention cohort.

Background The low-density lipoprotein receptor (LDLR) plays a significant role in maintaining the cellular cholesterol homeostasis. Mutations in the LDLR gene can lead to a significant rise in plasma LDL levels that may result in an increased risk of atherosclerosis and coronary heart disease. The purpose of this study was to assess the potential association of the LDLR rs688 polymorphism with cardiovascular disease (CVD) in patients with end-stage kidney disease (ESKD) undergoing hemodialysis. Methods In this case-control study the polymorphism was genotyped by the allele specific PCR method in 800 patients with ESKD and 500 healthy controls. The genotype and allele distribution was compared in subgroups of patients with CVD (552) versus those without CVD (248). Results A significant difference was observed in genotype distribution among ESKD patients and healthy controls. The frequencies of the T allele and TT genotype in ESKD group were significantly higher, with OR (95% CI) 2.2 (1.87–2.6), p p p p Conclusions The present study is the first to demonstrate the association of the LDLR gene polymorphism with increased susceptibility to cardiovascular disease in ESKD patients. This finding needs further investigation to confirm that LDLR rs688 might be a novel genetic risk factor with some prognostic capacity for CVD in ESKD patients.

Background: Familial hypercholesterolemia (FH), mainly caused by LDL receptor gene mutation is attracting a lot of attention associated with the development of novel therapies. However, rare mutations tend to be ethnicity-specific, hence, it is always difficult to determine pathogenicity of LDL receptor gene mutation in a single individual in a certain ethnicity. Currently, little data exist on the pathogenic mutations of LDL receptor in Japanese familial hypercholesterolemia (FH). Objective: We aimed to catalogue the pathogenic mutations of LDL receptor gene in the 2 major Japanese FH-care centers (Kanazawa University and National Cerebral and Cardiovascular Center Research Institute), where genetic testing of FH has been performed centrally upon requests from institutes all over Japan during more than past two decades. Methods: 796 FH subjects from 472 families who had nonsynonymous mutations in LDL receptor gene were included in this study. Genetic mutations were analyzed for mutations by Sanger sequencing as well as by multiplex ligation probe dependent amplification (MLPA) technique for large rearrangements. Pathogenic mutations were defined either as 1) protein truncated variants, 2) registered as pathogenic in Clinvar, or Human Gene Mutation Database (HGMD), or meet the criteria of American College of Medical Genetics and Genomics (ACMG) guideline, or 3) CADD-score > 10. Results: We found 138 different mutations. Among them, 132 mutations were considered as pathogenic, including 19 large rearrangement mutations. Whereas, 6 missense mutations were classified as variants of unknown significance (VUS). A single mutation accounted for as much as 41 % of the FH subjects recruited from Kanazawa University mainly due to founder gene effect, whereas, many singleton mutations were found from National Cerebral and Cardiovascular Center Research Institute located in Osaka. Conclusions: We provided the largest catalogue of pathogenic mutations of LDL receptor gene in Japanese FH. This could aid to determine the pathogenicity of the LDL receptor genetic mutations not only in Japanese but also in other ethnicities.

Background and aims Familial hypercholesterolaemia has not been previously described in the Vietnamese population. We aimed to describe the features of patients with homozygous familial hypercholesterolaemia (hoFH) in Vietnam and the outcomes of screening family members using genetic and cholesterol testing. Methods Mutation testing by massively parallel sequencing for genes causative of FH was undertaken in five index cases presenting to a single cardiac center with a presumptive diagnosis of hoFH. Cascade testing of all available family members was subsequently undertaken. The number of new cases of FH detected and commenced on lipid-lowering treatment was evaluated. Results All five index cases had true homozygous mutations in the LDL receptor gene (LDLR). Cascade screening was undertaken in four families. 107 relatives were screened and FH was identified in 56 relatives (52%), including 3 new cases of hoFH. Only 5 FH relatives (9%) were subsequently treated owing to the adverse perceptions and comparative high cost of drug treatment, and lack of awareness of FH among patients and local doctors. Conclusions HoFH due to LDLR mutations is a severe disorder in Vietnam that needs early detection and treatment with LDL-cholesterol lowering drugs. Cascade testing of families allows effective detection of new cases of FH that may also benefit from early treatment. However, convincing patients to commence statin treatment is a challenge. Extended education and awareness programs and treatment subsidies are imperative to improve the care of patients and families suffering from FH in Vietnam.

We report on the case of an 8-year-old Mexican male, with a 3-year-old clinical diagnosis of familial hypercholesterolemia, and the difficulties encountered in his treatment while in our care. His treatment started with a regimen consisting of ezetimibe/simvastatin, cholestyramine, and a dietary plan of 1600 calories, with a limited intake of 200 mg of cholesterol per day. Problems arose when the patient’s low-density lipoprotein cholesterol (LDL) levels did not meet ideal targets, which prompted the use of LDL cholesterol apheresis (not available in Mexico) for 6 months. As a last resort, PCSK9 inhibitors were administered but the LDL levels remained in the 600 mg/dL range. AmbryGenetics conducted a genetic test employing the Sanger method. The results suggested that there were 2 different mutations for each allele of the same LDL receptor gene (c.249delTinsGG and p.(Cys109Arg)), located in exons 3 and 4, respectively. We identified compound heterozygous mutations in our index case, with him having both the p.C109R mutation (from the maternal lineage), as well as a c.249delTinsGG mutation (from the paternal lineage). The p.C109R mutation has been previously reported, not only in Mexico, but in European regions (Germany, Czech Republic, Ireland, Italy) as well. Functional studies indicated a residual enzymatic activity of 15% to 30% for heterozygotes. To date, the variant c.249delTinsGG has not been reported. This case study illustrates the fact that in Mexico there are limited options available for treatment in such a scenario. As medical professionals, we are limited by the tools at our disposal.

Aim: Familial Hypercholesterolaemia (FH) is an autosomal disorder of lipid metabolism presenting increased cardiovascular risk due to lifelong exposure to high LDL levels. LDLR mutations are the cause of disease in about 90% of the cases, but proof of pathogenicity has only been obtained for about 10% of the variants. The lack of functional characterization of variants found in patients with a clinical diagnosis of FH makes it difficult to reach a definite FH diagnosis. In the Portuguese Familial Hypercholesterolemia Study (PFHS), 142LDLR alterations were found in 861 index patients and their relatives up to date. Until now, 82 of these alterations have already been proved to be mutations causing disease or are established null alleles and 15 were classified by in vitro studies as non-pathogenic. The remaining 38 variants, 21 of unknown significance (VUS), found in 102 index cases have not been yet functionally characterized. Project grant FCT_PTDC/SAU-GMG/101874/2008; UID/MULTI/04046/2013 centre grant from FCT, Portugal (to BioISI) N/A

Familial hypercholesterolemia (FH) is an autosomal dominant genetic disease caused mainly by LDL receptor (Ldlr) gene mutations. Unlike FH patients, heterozygous Ldlr knockout (KO) mice do not show a dominant FH trait. Hamsters, like humans, have the cholesteryl ester transfer protein, intestine-only ApoB editing and low hepatic cholesterol synthesis. Here, we generated Ldlr-ablated hamsters using CRISPR/Cas9 technology. Homozygous Ldlr KO hamsters on a chow diet developed hypercholesterolemia with LDL as the dominant lipoprotein and spontaneous atherosclerosis. On a high-cholesterol/high-fat (HCHF) diet, these animals exhibited severe hyperlipidemia and atherosclerotic lesions in the aorta and coronary arteries. Moreover, the heterozygous Ldlr KO hamsters on a short-term HCHF diet also had overt hypercholesterolemia, which could be effectively ameliorated with several lipid-lowering drugs. Importantly, heterozygotes on 3-month HCHF diets developed accelerated lesions in the aortas and coronary arteries. Our findings demonstrate that the Ldlr KO hamster is an animal model of choice for human FH and has great potential in translational research of hyperlipidemia and coronary heart disease., Highlights • Ldlr knockout hamsters were successfully generated by using the CRISPR/Cas9 editing system. • Loss of one copy of the Ldlr gene predisposes hamsters to diet-induced hyperlipidemia and coronary atherosclerosis. • Heterozygous Ldlr KO hamsters differentially respond to different lipid-lowering drugs. • Homozygous Ldlr KO hamsters on a chow diet develop severe hypercholesterolemia and spontaneous atherosclerosis. Genetically engineered animal models, especially mouse models, have been widely used to study the pathogenesis of cardiovascular disease. However, distinct differences in the metabolic profiles of mice and humans limit further applications of mouse models toward understanding atherosclerosis in humans. In the present study, we use the CRISPR/Cas9 editing system to delete the Ldlr gene in hamsters, a species exhibiting similar metabolic features to those of humans. Diet-induced heterozygous Ldlr KO hamsters show hyperlipidemia with atherosclerotic lesions in both the aorta and coronary arteries, which has been observed in FH patients but not in mice. Moreover, aged homozygous Ldlr KO hamsters on a chow diet display severe hypercholesterolemia and spontaneous atherosclerosis. Our work explores a human-like animal model for basic and translational research of human atherosclerosis.

Objective To evaluate the effectiveness of criteria based on child-parent assessment in predicting familial hypercholesterolemia (FH)-causative mutations in unselected children with hypercholesterolemia. Study design LDLR, APOB , and PCSK9 genes were sequenced in 78 children and adolescents (mean age 8.4 ± 3.7 years) with clinically diagnosed FH. The presence of polygenic hypercholesterolemia was further evaluated by genotyping 6 low-density lipoprotein cholesterol (LDL-C)-raising single-nucleotide polymorphisms. Results Thirty-nine children (50.0%) were found to carry LDLR mutant alleles but none with APOB or PCSK9 mutant alleles . Overall, 27 different LDLR mutations were identified, and 2 were novel. Children carrying mutations showed higher LDL-C (215.2 ± 52.7 mg/dL vs 181.0 ± 44.6 mg/dL, P .001) and apolipoprotein B levels (131.6 ± 38.3 mg/dL vs 100.3 ± 30.0 mg/dL, P .004), compared with noncarriers. A LDL-C of ~190 mg/dL was the optimal value to discriminate children with and without LDLR mutations. When different diagnostic criteria were compared, those proposed by the European Atherosclerosis Society showed a reasonable balance between sensitivity and specificity in the identification of LDLR mutations. In children without mutation, the FH phenotype was not caused by the aggregation of LDL-C raising single-nucleotide polymorphisms. Conclusions In unselected children with hypercholesterolemia, LDL-C levels >190 mg/dL and a positive family history of hypercholesterolemia appeared to be the most reliable criteria for detecting FH. As 50% of children with suspected FH did not carry FH-causing mutations, genetic testing should be considered.

Background— Homozygous familial hypercholesterolemia (HoFH) is a rare disease characterized by elevated plasma levels of low-density lipoprotein cholesterol (LDL-C) and extremely high risk of premature atherosclerotic cardiovascular disease. HoFH is caused by mutations in several genes, including LDL receptor ( LDLR ), apolipoprotein B ( APOB ), proprotein convertase subtilisin/kexin type 9 ( PCSK9 ), and LDL protein receptor adaptor 1 ( LDLRAP1 ). No epidemiological studies have assessed HoFH prevalence or the clinical and molecular characteristics of this condition. Here, we aimed to characterize HoFH in Spain. Methods and Results— Data were collected from the Spanish Dyslipidemia Registry of the Spanish Atherosclerosis Society and from all molecular diagnoses performed for familial hypercholesterolemia in Spain between 1996 and 2015 (n=16 751). Clinical data included baseline lipid levels and atherosclerotic cardiovascular disease events. A total of 97 subjects were identified as having HoFH—of whom, 47 were true homozygous (1 for APOB , 5 for LDLRAP1 , and 41 for LDLR ), 45 compound heterozygous for LDLR , 3 double heterozygous for LDLR and PSCK9 , and 2 double heterozygous for LDLR and APOB . No PSCK9 homozygous cases were identified. Two variants in LDLR were identified in 4.8% of the molecular studies. Over 50% of patients did not meet the classical HoFH diagnosis criteria. The estimated HoFH prevalence was 1:450 000. Compared with compound heterozygous cases, true homozygous cases showed more aggressive phenotypes with higher LDL-C and more atherosclerotic cardiovascular disease events. Conclusions— HoFH frequency in Spain was higher than expected. Clinical criteria would underestimate the actual prevalence of individuals with genetic HoFH, highlighting the importance of genetic analysis to improve familial hypercholesterolemia diagnosis accuracy.

The search for two mutations, FH-Helsinki and FH-North Karelia, in LDL receptor gene was carried out in patients with familial hypercholesterolemia from St. Petersburg (80 families) and Petrozavodsk (80 families) using allele-specific PCR and analysis of single-stranded DNA fragment conformation polymorphism (SSCP analysis) with subsequent sequencing. The FH-North Karelia mutation was found in one family in St. Petersburg and in one family in Petrozavodsk, while FH-Helsinki mutation was not detected in any of the samples. Hence, the two "Finnish" mutations together responsible for 2/3 familial hypercholesterolemia cases in Finland were extremely rare in the Russian regions neighboring Finland.

Summary Familial hypercholesterolemia (FH) is a frequent monogenetic disease (1/500 for heterozygous and 1/1,000,000 for homozygous). The FH patients are exposed to a dramatic increase of vascular risk of about 50% for men and 30% for women compared to the general population. The diagnosis can be suspected in case of high plasma concentration of LDL-C over 2.20 mg/dL, first relatives with FH in the family, xantomas and early cardiovascular events. The “Simon Broone criteria” or the Deutch scale are useful tools to ascertain the diagnosis but DNA testing is the gold standard. The mutations are mainly located on the LDL receptor gene and less frequently on Apo B100 or PCSK9 genes. The “cascade” testing of the family from the index patient is a critical step to detect new cases and start early treatment. Long-term treatment with statins has dramatically decreased the vascular risk to the level of the general population. In primary prevention, LDL-C should be less than 130 mg/dL and in secondary prevention less than 100 mg/dL (as a best

Male and female rats were fed diets supplemented with cholesterol and palm fat at 10 and 50 g/kg, respectively; serum, hepatic tissue and faeces were analysed. Cholesterol supplementation significantly increased serum and hepatic cholesterol both in male and female rats. Male and female rats fed the cholesterol-containing diet differed significantly in serum cholesterol concentration (2.48 µmol/mL vs 2.92 µmol/mL), concentration of serum triacylglycerols, but not in hepatic cholesterol concentration. The serum and hepatic cholesterol concentrations correlated non-significantly in male rats (r=0.491; P=0.063) and significantly in female rats (r=0.818; P

Some cases of hypercholesterolemia observed in childhood present a high risk of premature cardiovascular disease, such as in monogenic dominantly inherited hypercholesterolemia, particularly familial hypercholesterolemia due to mutations on the LDL receptor gene. This article, jointly written by the Societe Francaise de Pediatrie Nutrition Committee and the Nouvelle Societe Francaise d'Atherosclerose, proposes recommendations for a screening strategy and management of childhood hypercholesterolemia. A practical approach to high-risk cases of inherited hypercholesterolemia is detailed and the dietary management, indications, and supervision of lipid-lowering drug therapy in children are discussed.

Familial hypercholesterolaemia is the most common monogenic disorder associated with premature coronary artery disease. Mutations are most frequently found in the LDL receptor gene. Clinical criteria can be used to make the diagnosis; however, genetic testing will confirm the disorder and is very useful for cascade screening. Early identification and adequate treatment can improve prognosis, reducing negative clinical cardiovascular outcomes. Patients with familial hypercholesterolaemia are considered at high cardiovascular risk and the treatment target is LDL cholesterol

Mutations within the low density lipoprotein (LDL)-receptor gene result in familial hypercholesterolemia, an autosomal dominant inherited disease. Clinical homozygous affected subjects die of premature coronary artery disease as early as in early childhood. We identified a girl at the age of five yr with clinical homozygous familial hypercholesterolemia presenting with achilles tendon xanthomas and arcus lipoides. Her total cholesterol reached up to 1050 mg/dL. Molecular characterization of the LDL-receptor gene revealed a homozygous p.W577R mutation. Despite intensive treatment interventions with the combination of diet, statins, colestipol, and LDL-apheresis, the patient developed symptomatic coronary artery disease at the age of 16 yr. Subsequently, orthotopic liver transplantation was performed to cure the defective LDL-receptor gene. Clinical follow-up for almost nine yr post-transplantation revealed excellent liver function, normal liver enzymes, normal LDL-cholesterol, and regression of both tendon xanthomas and symptomatic coronary artery disease. In conclusion, liver transplantation can effectively reduce LDL-cholesterol in a familial hypercholesterolemia recipient with subsequent regression of xanthomas and atherosclerosis. Timing is extremely important in these exceptional cases to exclude the demand for heart transplantation due to severe coronary artery disease. In addition, the identification of the LDL-receptor as etiology of clinical homozygous hypercholesterolemia is a prerequisite once liver transplantation is considered as therapeutic option.

Conjugated linoleic acids (CLA) have attracted scientific interest due to their potential beneficial effects on atherosclerosis. Recently, a mixture of CLA isomers was demonstrated to upregulate LDL receptor expression in the human hepatoma cell line HepG2. However, the underlying mechanisms remain to be resolved. Thus, the aim of this study was to elucidate how CLA mediates upregulation of LDL receptor in HepG2 cells and whether this upregulation is isomer-specific. The results revealed that LDL receptor promoter activity and mRNA expression were strongly induced upon treatment with t10c12-CLA (P0.05), whereas c9t11-CLA and linoleic acid (LA) had no effect. In addition, only treatment with t10c12-CLA markedly induced mRNA expression of SREBP-2 and HMG-CoA reductase and slightly induced that of SREBP-1 (P0.05). Using SREBP-2 knockdown cells, we could demonstrate that the effect of t10c12-CLA on LDL receptor gene transcription was significantly reduced when compared to control cells (P0.05). When using SREBP-1 knockdown cells the effect of t10c12-CLA on LDL receptor mRNA only slightly decreased compared to control cells. In addition, using different deletion constructs of the LDL receptor gene promoter we showed that the induction of the LDL receptor by t10c12-CLA is independent of the AP-1 motif in the LDL receptor promoter. In conclusion, the present study revealed that transcriptional activation of the LDL receptor gene by t10c12-CLA is dependent on the upregulation of SREBP-2 and is probably due to the activation of the SRE-1 in the LDL receptor gene promoter in HepG2 cells. Thus, the decreased plasma cholesterol levels in response to CLA as observed in a limited number of animal and human studies might be explained by an enhanced uptake of VLDL and LDL cholesterol via hepatic LDL receptors. However, it provides no explanation for the outcome of most human studies reporting unaltered or even increased plasma and LDL cholesterol concentrations in response to supplementation with CLA.

Department of Molecular GeneticsUniversity of Texas Southwestern Medical Center5323 Harry Hines Boulevard plasma cholesterol levels and the removal of LDL fromDallas, Texas 75390 the circulation is generally well known. Humans andrabbits that are homozygous for naturally occurring re-ceptor-inactivatingmutationsandmiceinwhichtheLDL

Receptors belonging to the low density lipoprotein receptor (LDLR) superfamily play important biological roles in addition to mediating the lipoprotein metabolism. The recent discovery of a novel mosaic LDLR family member by us (Yamazaki H, Bujo H, Kusunoki J, Seimiya K, Kanaki T, Morisaki N, Schneider WJ, and Saito Y J Biol Chem 271: 24761-24768, 1996) and others, which we termed LR11, offers the opportunity to gain new insights into receptor multifunctionality. The expression of a 250-kDa mosaic LDLR family member, which we termed LR11 due to the presence of 11 ligand binding repeats, is markedly induced during the process of atherogenesis in two animal models. The highest induction of LR11 occurs in the intimal smooth muscle cells (SMCs) of atheromatous lesions. In agreement with the correlation of LR11 induction during increased cell proliferation in vivo, cultured SMCs showed a marked increase in LR11 expression in the proliferative phase. Furthermore, such proliferation-dependent expression of LR11 could be observed in a cultured neuroblastoma cell line, which was established to be a suitable in vitro model for proliferation and differentiation. Possible involvement of LR11 in the cellular proliferation sheds new light on the recently proposed novel functions of the LDL receptor gene family in atherosclerosis.

Recent research has focused on the rapid detection of new LDL receptor gene variants and large scale screening for known mutations. Whether the nature of the mutation in the LDL receptor gene in familial hypercholesterolaemia determines clinical variability has been examined, as well as the potential value of detecting mutation carriers for clinical practice. There is also evidence that some patients with clinical familial hypercholesterolaemia do not have detectable defects in the LDL receptor or apolipoprotein B. Curr Opin Lipidol 9:141–147. © 1998 Rapid Science Ltd

Fasting is associated with a reduction in serum T3 and T4 and a rise of plasma LDL cholesterol. We hypothesized that an hypothyroid-like condition induced by fasting is responsible for the rise in LDL cholesterol. We therefore examined the relation between changes in thyroid hormone and cholesterol metabolism in rats fasted for 0, 8, 12, 24 or 48 h. Fasting resulted in a decrease of liver 5′-deiodinase mRNA from 8 h (to 50%, p n =6), of serum T3 from 12 h and of serum T4 at 48 h; serum TSH remained unchanged. Furthermore, plasma LDL cholesterol increased from 24 h onwards preceded by a decrease of liver LDL receptor mRNA which in turn is related to serum T3 ( r =0.55, p n =19). Adding T3 at a concentration such that normal T3 levels are maintained during 48 h fasting, prevents the decrease in the LDL receptor mRNA. Fasting did not change hepatic HMG CoA reductase mRNA but decreased cholesterol 7 α -hydroxylase mRNA, which however was not related to the decrease of serum T3. In conclusion: (1) Fasting induces a hypothyroid-like condition in which inhibition of hepatic conversion of T4 into T3 may be responsible for the decrease of serum T3. (2) Fasting induces an increase of plasma LDL cholesterol, apparently caused by a decrease of hepatic LDL receptor gene expression which is (partly) related to the fall in serum T3. (234).

The year 1997 celebrated the 20th anniversary of the European Lipoprotein Club. Sessions explored topics in the line of classical concepts and forthcoming advances in the field of basic and clinical research on lipoproteins. Participants from 18 European countries attended the conference. Recent Developments in Lipoprotein Research, were reviewed by Thomas Olivecrona (Umea, Sweden), who gave a perspective on lipolysis; and Gerd Assmann (Munster, Germany), who overviewed epidemiological data of the PROCAM study and focused on the biochemical and genetic components of reverse cholesterol transport. Session I, chaired by Katriina Aalto Setala (Tampere, Finland) and Marten Hofker (Leiden, Netherlands) was dedicated to `Lipoprotein receptors (old and new)'. Various structural and functional aspects were reported for the newcomers in the ever enriching LDL receptor gene family (VLDLR, LR7/8B, LR11, Megalin, RAP-related proteins). However, a decade of identification of LDL receptors gene defects reveals now that phenocopies of familial hypercholesterolemia may be linked to a third, yet unknown locus. Identification of pathways which clear HDL is underway. Session II, chaired by David Bowyer (Cambridge, United Kingdom) and Richard W James (Geneva, Switzerland), was entitled `Significance of lipoprotein heterogeneity (metabolic and pathological aspects)'. Factors involved in lipoprotein modification (dense LDL, oxidation), transient production (post prandial, VLDL synthesis) or degradation (complement activation) and controversial hypotheses on their links with atherosclerosis were discussed. Session III on `Novel methodologies for lipoprotein research' was chaired by Rudolph Poledne (Prague, Czech Republic) and Armin Steinmetz (Marburg, Germany). Simple technologies for routine assessment of lipoprotein metabolism, as well as the most sophisticated ones, to study lipid and free radical exchanges between particles, were presented.

In patients heterozygous for familial hypercholesterolemia, the low-density lipoprotein (LDL) cholesterol lowering effect of beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitors may depend on the nature of the mutation in the LDL receptor gene. To test this hypothesis, we compared the response to simvastatin, 20 mg daily for 9 weeks, between heterozygous carriers of functionally different classes of mutations, i.e. mRNA negative or mRNA positive mutations. Out of 116 consecutive, unrelated patients with familial hypercholesterolemia, 27 patients were selected for molecular analyses: 14 patients with mRNA negative and 13 with mRNA positive mutations. Before simvastatin treatment, patients with mRNA negative mutations had higher levels of LDL cholesterol, lower levels of high-density lipoprotein (HDL) cholesterol and significantly more often tendon xanthomas, compared to patients with mRNA positive mutations. Simvastatin reduced the mean fasting LDL cholesterol levels to a similar percentage in the mRNA negative and mRNA positive patients (37, 36%, respectively, 95% CI of difference--8 to 5%, P = 0.2). This effect was similar to the 37% decrease observed in our total series of patients with familial hypercholesterolemia (n = 116). The increase in mean concentration of HDL cholesterol was greater in the mRNA negative group than in the mRNA positive group (16, 0%, respectively, 95%, CI of difference 8-25%, P = 0.002) independent of the response of total triglycerides to simvastatin. The percentage LDL cholesterol lowering response varied among multiple carriers of the same mutation, even in the case of mRNA negative mutations. We conclude that the percentage LDL lowering response to simvastatin treatment was similar in patients with mRNA negative and mRNA positive mutations. Moreover, variation of this response within multiple carriers of the same mutation suggests an influence of additional factors.

This study was undertaken to determine the effect of transient overexpression of hepatic cholesterol 7α-hydroxylase on low density lipoprotein (LDL) cholesterol transport in mice lacking LDL receptors (LDL receptor−/−). Primary overexpression of hepatic 7α-hydroxylase in LDL receptor−/− mice was accompanied by a dose-dependent decrease in the rate of LDL cholesterol appearance in plasma (whole body LDL cholesterol transport) and a corresponding reduction in circulating LDL cholesterol levels. The increase in hepatic 7α-hydroxylase activity necessary to achieve a 50% reduction in plasma LDL cholesterol concentrations was ∼10-fold. In comparison, cholestyramine increased hepatic 7α-hydroxylase activity ∼3-fold and reduced plasma LDL cholesterol concentrations by 17%. This study demonstrates that augmentation of hepatic 7α-hydroxylase expression is an effective strategy for lowering plasma LDL concentrations even in animals with a genetic absence of LDL receptors.

Molecular biological studies in familial hypercholesterolaemia have indicated that the severity of the disease, at least in terms of circulating LDL-cholesterol levels, varies depending on the kind of structural defect found in the LDL receptor gene. This may well influence individual risk and signal that more aggressive therapeutic intervention is required. The discovery of the statins has revolutionized therapy for the familial hypercholesterolaemia heterozygote, but the prognosis for the rare homozygote, who fails to respond adequately to therapy, remains poor unless extreme measures are taken.

BACKGROUND: In the Netherlands, a screening programme was set up in 1994 in order to identify all patients with familial hypercholesterolaemia (FH). After 15 years of screening, we evaluated the geographical distribution, possible founder effects and clinical phenotype of the 12 most prevalent FH gene mutations. METHODS: Patients who carried one of the 12 most prevalent mutations, index cases and those identified between 1994 and 2009 through the screening programme and whose postal code was known were included in the study. Low-density lipoprotein cholesterol (LDL-C) levels at the time of screening were retrieved. The prevalence of identified FH patients in each postal code area was calculated and visualised in different maps. RESULTS: A total of 10,889 patients were included in the study. Mean untreated LDL-C levels ranged from 4.4 to 6.4 mmol/l. For almost all mutations, a region of high prevalence could be observed. In total, 51 homozygous patients were identified in the Netherlands, of which 13 true homozygous for one of the 12 most prevalent mutations. The majority of them were living in high-prevalence areas for that specific mutation. CONCLUSIONS: Phenotypes with regard to LDL-C levels varied between the 12 most prevalent FH mutations. For most of these mutations, a founder effect was observed. Our observations can have implications with regard to the efficiency of molecular screening and physician's perception of FH and to the understanding of the prevalence and distribution of homozygous patients in the Netherlands.

Familial hypercholesterolemia (FH) is associated with an increased risk of premature coronary heart disease. Molecular identification of these patients can reduce the burden of mortality from cardiovascular disorders simply by the correct identification of the disease early in life, followed by counseling and appropriate lifestyle modifications, and therapeutic measures when required. Recent studies show that, in Portugal, this disease is severely under-diagnosed. After more than 10 years of research through the Portuguese FH Study, it is now possible to translate the original research results into clinical application. AIMS: The main aims of the present work were to determine whether clinical characterization is sufficient to identify these individuals at high risk of developing CHD and to evaluate the clinical applicability of molecular diagnosis for FH. METHODS: All patients described in this study were recruited for the Portuguese FH Study. The diagnostic criteria used to select the index patients were adapted from the Simon Broome Heart Research Trust. To analyze the usefulness of the molecular diagnosis, graphs of total and LDL cholesterol values by age were constructed for 622 possible FH patients. The lipid profile of patients genetically identified as having FH, before and under medication, were analyzed to assess whether these patients were receiving appropriate treatment. The data are shown separately for children and adults and for female and male propositi (index cases and hypercholesterolemic relatives), both with and without a detectable mutation in the LDLR gene. RESULTS: The Portuguese FH Study has already genetically identified 404 individuals (171 index patients and 233 relatives) among more than one thousand individuals sent for study. A total of 78 different mutations in the LDLR gene were found in 171 index patients, 2 different mutations were found in the apoB gene of 4 patients and 2 patients had a unique PCSK9 mutation. Statistical analysis revealed that there are significant differences between total cholesterol (p < 0.001) and apoB (p = 0.026) values in the group of children (male and female) with and without a mutation in LDLR. For female children LDL values were also significantly different (p < 0.001) between subgroups but for male children this difference did not reach statistical significance. In adult women there is a statistically significant difference for total cholesterol (p = 0.049), LDL cholesterol (p = 0.031) and apoB (p = 0.003) values in the subgroups with and without a LDLR mutation. In adult males there is a statistical difference for total cholesterol (p = 0.002). LDL cholesterol (p = 0.003) and apoB (p = 0.0023) in subgroups with and without an LDLR mutation. Nevertheless there was considerable dispersion of values and individually it is not possible to distinguish between patients with and without a mutation in the LDLR gene, based only on lipid profile. CONCLUSIONS: By analysis of the clinical data of 696 possible FH patients, the present report shows evidence that clinical characterization is not sufficient to distinguish between patients with genetic or environmental dyslipidemia, and so molecular diagnosis is useful in clinical practice, allowing correct identification of FH patients and their relatives, and the early implementation of therapeutic measures to reduce the elevated cardiovascular risk of these patients. In general, molecular diagnosis of FH is feasible and could be obtained in 1-2 months if the technology is available. In Portugal the test will be offered to the population by our Institute at a cost of about 500 euros, like many other genetic tests or exams such as nuclear magnetic resonance.