Search

• HoFH requires prompt diagnosis and intensive treatment to prevent CVD in childhood. • Couples both carrying an FH variant run a 25% chance of having a child with HoFH. • Prenatal genetic counseling for HoFH should be performed on a case-by-case basis. • Clinicians should discuss all available diagnostic and reproductive options. • Discuss treatment outlook considering FH genotype and weighing parental preferences. Homozygous familial hypercholesterolemia (HoFH) is a rare, potentially life-limiting, inherited disorder of lipoprotein metabolism characterized by extremely high low-density lipoprotein cholesterol levels. When both parents have heterozygous FH, there is a 25% chance they will conceive a child with HoFH. Here we describe our clinical experience with two such prospective parent couples who were counseled regarding reproductive options and prenatal testing for HoFH. These cases showcase how, in consultation with a molecular geneticist and pediatric cardiologist, parents may be informed of the prognosis and treatment outlook of HoFH based on the FH-variants carried, to ultimately make personal decisions on reproductive options. One couple opted for prenatal testing and termination of pregnancy in case HoFH was found, while the other accepted the risk without testing. We review the available literature on preconception counseling for HoFH and provide practical guidance to clinicians counseling at-risk couples. Optimal counseling of prospective parents may help prevent future physical and psychological problems for both parent and child. [ABSTRACT FROM AUTHOR]

Homozygous familial hypercholesterolemia (hoFH) is either diagnosed on the identification of pathogenic genetic variants in LDLR , APOB , or PCSK9 or by phenotypic parameters of which an extremely elevated LDL-C level >13 mmol/L (>500 mg/dL) is the most prominent hallmark. Little is known about the clinical spectrum in children with hoFH. We set out to investigate the phenotypical spectrum of genetically defined hoFH in our pediatric cohort and evaluated how many pediatric patients, now classified as heterozygous, carry a second mutation, which would reclassify these patients as hoFH. We analyzed the data of a total of 1903 children with molecularly proven FH. Subsequently we performed candidate gene sequencing in the cohort of heterozygous familial hypercholesterolemia children in whom the LDL-C level was above the lowest level measured in the pediatric patients with hoFH. Of our 13 hoFH children, 8 (62%) had LDL-C levels below the clinical hoFH criteria of 13 mmol/L (500 mg/dL). In the remaining 1890 patients with heterozygous familial hypercholesterolemia, 64 (3.4%) had LDL-C levels equal to or above the lowest LDL-C level in a patient with hoFH carrying 2 deleterious variants (8.36 mmol/L or 323.3 mg/dL). No additional pathogenic variants in LDLR and APOB were identified. In 2 related patients, a PCSK9 gain of function mutation was found. We show that LDL-C levels vary among pediatric patients with molecularly proven hoFH, and that most of these patients do not meet the clinical LDL-C criteria for hoFH. The levels overlap with LDL-C levels in true heterozygous patients. This warrants a critical reappraisal of the current LDL-C cutoffs for the phenotypic diagnosis of hoFH in children. • LDL-C levels vary greatly among pediatric patients with genetically defined hoFH. • Almost half of the pediatric patients with hoFH do not meet the diagnostic LDL-C threshold. • There is an overlap between the phenotype of severe pediatric heFH and hoFH. • The strict separation between hoFH and heFH should be reconsidered. [ABSTRACT FROM AUTHOR]

Background Patients with autosomal dominant hypercholesterolemia (ADH), caused by mutations in either low-density lipoprotein receptor ( LDLR ), apolipoprotein B ( APOB ), or proprotein convertase subtilisin-kexin type 9 ( PCSK9 ) are characterized by high low-density lipoprotein cholesterol levels and in some studies also high lipoprotein(a) (Lp(a)) levels were observed. The question remains whether this effect on Lp(a) levels is gene-dose–dependent in individuals with either 0, 1, or 2 LDLR or APOB mutations. Objective We set out to study whether Lp(a) levels differ among bi-allelic ADH mutation carriers, and their relatives, in the Netherlands. Methods Bi-allelic ADH mutation carriers were identified in the database of the national referral laboratory for DNA diagnostics of inherited dyslipidemias. Family members were invited by the index cases to participate. Clinical parameters and Lp(a) levels were measured in bi-allelic ADH mutation carriers and their heterozygous and unaffected relatives. Results We included a total of 119 individuals; 34 bi-allelic ADH mutation carriers (20 homozygous/compound heterozygous LDLR mutation carriers (HoFH), 2 homozygous APOB mutation carriers (HoFDB), and 12 double heterozygotes for an LDLR and APOB mutation), 63 mono-allelic ADH mutation carriers (50 heterozygous LDLR [HeFH], 13 heterozygous APOB [HeFDB] mutation carriers), and 22 unaffected family members. Median Lp(a) levels in unaffected relatives, HeFH, and HoFH patients were 19.9 (11.1–41.5), 24.4 (5.9–70.6), and 47.3 (14.9–111.7) mg/dL, respectively ( P = .150 for gene-dose dependency). Median Lp(a) levels in HeFDB and HoFDB patients were 50.3 (18.7–120.9) and 205.5 (no interquartile range calculated), respectively ( P = .012 for gene-dose-dependency). Double heterozygous carriers of LDLR and APOB mutations had median Lp(a) levels of 27.0 (23.5–45.0), which did not significantly differ from HoFH and HoFDB patients ( P = .730 and .340, respectively). Conclusion A (trend toward) increased plasma Lp(a) levels in homozygous ADH patients compared with both heterozygous ADH and unaffected relatives was observed. Whether increased Lp(a) levels in homozygous ADH patients add to the increased cardiovascular disease risk and whether this risk can be reduced by therapies that lower both low-density lipoprotein cholesterol and Lp(a) levels remains to be elucidated. [ABSTRACT FROM AUTHOR]

Introduction Autosomal dominant hypercholesterolemia (ADH), characterized by high-plasma low-density lipoprotein cholesterol (LDL-C) levels and premature cardiovascular disease (CVD) risk, is caused by mutations in LDLR , APOB , and/or PCSK9 . Objective To describe the clinical characteristics of “double-heterozygous carriers,” with 2 mutations in 2 different ADH causing genes, that is, LDLR and APOB or LDLR and PCSK9 . Methods Double heterozygotes were identified in the database of the national referral laboratory for DNA diagnostics of inherited dyslipidemias. We collected the medical data (comprising lipids and CVD events) from double heterozygotes and compared these with data from their heterozygous and unaffected relatives and homozygote/compound heterozygous LDLR mutation carriers, identified in a previously described cohort (n = 45). Results A total of 28 double heterozygotes (23 LDLR/APOB and 5 LDLR/PCSK9 mutation carriers) were identified. Off treatment, LDL-C levels were significantly higher in double heterozygotes (mean ± SD, 8.4 ± 2.8 mmol/L) compared with 28 heterozygous (5.6 ± 2.2) and 18 unaffected relatives (2.5 ± 1.1; P ≤ .01 for all comparisons) and significantly lower compared with homozygous/compound heterozygous LDLR mutation carriers (13.0 ± 5.1; P < .001). Conclusions Double-heterozygous carriers of mutations in ADH genes express an intermediate phenotype compared with heterozygous and homozygous/compound heterozygous carriers and might well be misconceived to suffer from a severe form of heterozygous ADH. The molecular identification of double heterozygosity is of relevance from both a screening and an educational perspective. [ABSTRACT FROM AUTHOR]

Background Familial hypercholesterolemia (FH) leads to premature coronary artery disease and aortic stenosis, with undertreated severe forms causing death at a young age. Lipoprotein apheresis (LA) is often required for lowering low-density lipoprotein cholesterol levels in severe FH. Objectives The objective of this study was to present the first experiences with LA in Malaysia, between 2004 and 2014. Methods We retrospectively collected data from patient records to assess the effectiveness, adverse effects, patient quality of life, and costs associated with an LA service for genetically confirmed homozygous and heterozygous FH. Results We treated 13 women and 2 men aged 6 to 59 years, 10 with homozygous and 5 with heterozygous FH, all on maximally tolerated cholesterol-lowering drug therapy, for a total of 65 patient-years. Acute lowering of low-density lipoprotein cholesterol post apheresis was 56.3 ± 7.2%, with time-averaged mean lowering of 34.9 ± 13.9%. No patients experienced any cardiovascular events during the period of receiving LA. Patients receiving LA experienced few side effects and enjoyed reasonable quality of life, but inability to continue treatment was frequent because of cost. Conclusion LA for severe FH can be delivered effectively in the short term in developing nations, but costs are a major barrier to sustaining this mode of treatment for this high-risk group of patients. New drug therapies for FH, such as the proprotein convertase subtilisin/kexin type 9 inhibitors, microsomal triglyceride transfer protein inhibitors, and apolipoprotein-B100 antisense oligonucleotides may allow improved care for these patients, but costs and long-term safety remain as issues to be addressed. [ABSTRACT FROM AUTHOR]

Background Familial hypercholesterolemia (FH) is caused by mutations in LDLR , APOB , or PCSK9 , and in a previous study, we identified a causative mutation in these FH genes in 95% (255 of 269) of children with the FH phenotype. It has been hypothesized that a polygenic form of hypercholesterolemia is present in FH patients in whom no mutation is identified in the 3 FH genes. Objective To address whether a polygenic form of hypercholesterolemia, defined as high-weighted effect of low-density lipoprotein cholesterol (LDL-C) raising SNPs expressed as the genetic risk score (GRS), is present in the remaining 14 children. Methods and results On reassessment of the molecular diagnosis and clinical phenotype, 8 FH kindreds met the criteria for hypercholesterolemia of unknown cause and were included in this study. We calculated a weighted GRS comprising 10 established LDL-C–associated SNPs and the APOE genotype in these index cases and evaluated whether the index cases were characterized by an increased GRS compared to 26 first-degree relatives. Phenotypically affected and unaffected individuals could not be distinguished based on any of the risk scores. Conclusions In this and our previous study, we show that a causal mutation in LDLR , APOB , and PCSK9 can be identified in almost all children with a definite clinical diagnosis of FH. In the small group of patients without a mutation, we did not observe a higher GRS compared with unaffected relatives, which suggests that the FH phenotype is not caused by the aggregate of LDL-C increasing SNPs. Our data imply that application of the GRS is not instrumental as a diagnostic tool to individually define clinically diagnosed FH patients with polygenic hypercholesterolemia in our study population. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this article is to briefly review but also to highlight the rationale, motivation, and methods in the process of identifying patients of all ages with familial hypercholesterolemia (FH), an often hidden but very important genetic disorder. Since the initiation of population screening for FH in 1994 in the Netherlands, a vast amount of experience has been gathered, addressing almost all issues that are encountered in population screening. [ABSTRACT FROM AUTHOR]

Abstract: 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 $ 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. [Copyright &y& Elsevier]

Familial hypercholesterolemia (FH) is a common inherited disease characterized by elevated low-density lipoprotein cholesterol (LDL-C) plasma levels and increased cardiovascular disease risk. Most patients carry a mutation in the low-density lipoprotein receptor gene (LDLR). Common and rare variants in the genes encoding adenosine triphosphate–binding cassette transporters G5 and G8 (ABCG5 and ABCG8) have been shown to affect LDL-C levels. The objective of this study was to investigate whether and to which extent heterozygous variants in ABCG5 and ABCG8 are associated with the hypercholesterolemic phenotype. We sequenced ABCG5 and ABCG8 in a cohort of 3031 clinical FH patients and compared the prevalence of variants with a European reference population (gnomAD). Clinical characteristics of carriers of putative pathogenic variants in ABCG5 and/or ABCG8 were compared with heterozygous carriers of mutations in LDLR. Furthermore, we assessed the segregation of one ABCG5 and two ABCG8 variants with plasma lipid and sterol levels in three kindreds. The frequencies of (likely) pathogenic LDLR, APOB, PCSK9, ABCG5, and ABCG8 variants in our FH cohort were 11.42%, 2.84%, 0.69%, 1.48%, and 0.96%, respectively. We identified 191 ABCG5 and ABCG8 variants of which 53 were classified as pathogenic or likely pathogenic. Of these 53 variants, 51 were either absent from a reference population or more prevalent in our FH cohort than in the reference population. LDL-C levels were significantly lower in heterozygous carriers of a (likely) pathogenic ABCG5 or ABCG8 variant compared to LDLR mutation carriers (6.2 ± 1.7 vs 7.2 ± 1.7 mmol/L, P <.001). The combination of both an ABCG5 or ABCG8 variant and a LDLR variant was found not to be associated with significant higher LDL-C levels (7.8 ± 2.3 vs 7.2 ± 1.7 mmol/L, P =.259). Segregation analysis in three families (nine carriers, in addition to the index cases, and 16 noncarriers) did not show complete segregation of the ABCG5/G8 variants with high LDL-C levels, and LDL-C levels were not different (3.9 ± 1.3 vs 3.5 ± 0.6 mmol/L in carriers and noncarriers, respectively, P =.295), while plasma plant sterol levels were higher in carriers compared to noncarriers (cholestanol: 10.2 ± 1.7 vs 8.4 ± 1.6 μmol/L, P =.007; campesterol: 22.5 ± 10.1 vs 13.4 ± 3.5 μmol/L, P =.008; sitosterol: 17.0 ± 11.6 vs 8.2 ± 2.6 μmol/L, P =.024). 2.4% of subjects in our FH cohort carried putative pathogenic ABCG5 and ABCG8 variants but had lower LDL-C levels compared to FH patients who were heterozygous carriers of an LDLR variant. These results suggest a role for these genes in hypercholesterolemia in FH patients with less severely elevated LDL-C levels. We did not find evidence that these variants cause autosomal dominant FH. • 2.4% of clinical familial hypercholesterolemia patients carry variants in ABCG5 and ABCG8. • ABCG5 or ABCG8 carriers have lower low-density lipoprotein cholesterol compared to LDLR mutation carriers. • ABCG5 and ABCG8 variants did not cosegregate with high low-density lipoprotein cholesterol in familial hypercholesterolemia families. [ABSTRACT FROM AUTHOR]

Background Mutations in the genes for the low-density lipoprotein receptor ( LDLR ), apolipoprotein B, and proprotein convertase subtilisin/kexin type 9 have been reported to cause heterozygous and homozygous familial hypercholesterolemia (FH). Objective The objective is to examine the influence of double heterozygous, compound heterozygous, or homozygous mutations underlying FH on the efficacy of alirocumab. Methods Patients from 6 alirocumab trials with elevated low-density lipoprotein cholesterol (LDL-C) and FH diagnosis were sequenced for mutations in the LDLR , apolipoprotein B, proprotein convertase subtilisin/kexin type 9, LDLR adaptor protein 1 ( LDLRAP1 ), and signal-transducing adaptor protein 1 genes. The efficacy of alirocumab was examined in patients who had double heterozygous, compound heterozygous, or homozygous mutations. Results Of 1191 patients sequenced, 20 patients were double heterozygotes (n = 7), compound heterozygotes (n = 10), or homozygotes (n = 3). Mean baseline LDL-C levels were similar between patients treated with alirocumab (n = 11; 198 mg/dL) vs placebo (n = 9; 189 mg/dL). All patients treated with alirocumab 75/150 or 150 mg every 2 weeks had an LDL-C reduction of ≥15% at either week 12 or 24. At week 12, 1 patient had an increase of 7.1% in LDL-C, whereas in others, LDL-C was reduced by 21.7% to 63.9% (corresponding to 39–114 mg/dL absolute reduction from baseline). At week 24, LDL-C was reduced in all patients by 8.8% to 65.1% (10–165 mg/dL absolute reduction from baseline). Alirocumab was generally well tolerated in the 6 trials. Conclusion Clinically meaningful LDL-C–lowering activity was observed in patients receiving alirocumab who were double heterozygous, compound heterozygous, or homozygous for genes that are causative for FH. [ABSTRACT FROM AUTHOR]

Background Mutation(s) in genes involved in the low-density lipoprotein receptor (LDLR) pathway are typically the underlying cause of familial hypercholesterolemia. Objective The objective of the study was to examine the influence of genotype on treatment responses with alirocumab. Methods Patients from 6 trials (n = 1191, including 758 alirocumab-treated; Clinicaltrials.gov identifiers: NCT01266876 ; NCT01507831 ; NCT01623115 ; NCT01709500 ; NCT01617655 ; NCT01709513 ) were sequenced for mutations in LDLR , apolipoprotein B ( APOB ), proprotein convertase subtilisin/kexin type 9 ( PCSK9 ), LDLR adaptor protein 1, and signal-transducing adaptor protein 1 genes. New mutations were confirmed by Sanger sequencing. Results One or more specific gene mutations were found in 898 patients (75%): 387 and 437 patients had heterozygous LDLR defective and negative mutations, respectively; 46 had a heterozygous APOB -defective mutation; 8 patients had a heterozygous PCSK9 gain-of-function mutation; 293 (25%) had no identifiable mutation in the genes investigated. LDL cholesterol reductions at Week 24 were generally similar across genotypes: 48.3% (n = 131) and 54.3% (n = 89) in LDLR -defective heterozygotes with alirocumab 75 mg Q2W (with possible increase to 150 mg at Week 12) and 150 mg Q2W, respectively; 49.7% (n = 168) and 60.7% (n = 88) in LDLR -negative heterozygotes; 54.1% (n = 20) and 50.1% (n = 6) in APOB -defective heterozygotes; 60.5% (n = 5) and 94.0% (n = 1) in PCSK9 heterozygotes; and 44.9% (n = 85) and 55.4% (n = 69) in patients with no identified mutations. Overall rates of treatment-emergent adverse events were similar for alirocumab vs controls (placebo in 5 trials, ezetimibe control or atorvastatin calibrator arm in 1 trial), with only a higher rate of injection-site reactions with alirocumab. Conclusions In this large patient cohort, individuals with a wide spectrum of mutations in genes underlying familial hypercholesterolemia responded substantially and similarly to alirocumab treatment. [ABSTRACT FROM AUTHOR]

Familial hypercholesterolemia (FH) is an autosomal dominant disorder with an associated high risk of coronary heart disease (CHD). The considerable variation in age of onset of CHD in patients with FH is believed to arise from conventional risk factors, as well as genetic variation other than in the low-density lipoprotein receptor gene. The degree to which currently known genetic variants can improve the prediction of CHD risk beyond conventional risk factors in this disorder was investigated. Fourteen genetic variants recently identified for association with CHD in a Dutch FH population were considered. Prediction models were constructed using Cox proportional hazards models, and predictive value was assessed using a concordance statistic (c statistic). A total of 1,337 patients with FH were completely genotyped for all genetic variants. Hazard ratios of the genetic variants ranged from 0.61 to 0.74 and 1.24 to 2.33. The c statistic of the CHD prediction model based on genetic variants was 0.59, denoting little discrimination. The model based on conventional risk factors had a c statistic of 0.75, denoting moderate discrimination. Adding genetic test results to this model increased the c statistic to 0.76. In conclusion, the contribution of 14 genetic variants to the prediction of CHD risk in patients with FH was limited. To improve genome-based prediction of CHD, larger numbers of genetic variants need to be identified that either on their own or in gene–gene interaction have substantial effects on CHD risk. [Copyright &y& Elsevier]

Although awareness of familial hypercholesterolemia (FH) is increasing, this common, potentially fatal, treatable condition remains underdiagnosed. Despite FH being a genetic disorder, genetic testing is rarely used. The Familial Hypercholesterolemia Foundation convened an international expert panel to assess the utility of FH genetic testing. The rationale includes the following: 1) facilitation of definitive diagnosis; 2) pathogenic variants indicate higher cardiovascular risk, which indicates the potential need for more aggressive lipid lowering; 3) increase in initiation of and adherence to therapy; and 4) cascade testing of at-risk relatives. The Expert Consensus Panel recommends that FH genetic testing become the standard of care for patients with definite or probable FH, as well as for their at-risk relatives. Testing should include the genes encoding the low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB), and proprotein convertase subtilisin/kexin 9 (PCSK9); other genes may also need to be considered for analysis based on patient phenotype. Expected outcomes include greater diagnoses, more effective cascade testing, initiation of therapies at earlier ages, and more accurate risk stratification. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Fetal exposure to maternal hypercholesterolemia increases the extent of fatty-streak formation in fetal aortas as well as the rate of progression, and may therefore increase coronary heart disease (CHD) risk later in life. We hypothesized that the risk of CHD in untreated individuals with familial hypercholesterolemia (FH) is more extreme when the disease is transmitted maternally. Methods: In a large Dutch pedigree carrying the V408M mutation in the low-density lipoprotein (LDL) receptor gene, 161 individuals over seven generations were identified for which FH status and parent of origin of FH were known. We calculated standardized mortality ratios (SMR) and compared the consequences of maternal and paternal inheritance of FH by Poisson regression analysis. Results: Maternally inherited FH was associated with significantly higher excess mortality than FH transmitted by fathers (relative risk 2.2; p =0.048): the SMR of maternal inheritance was 2.49 (95% confidence interval (CI) 1.45–3.99; p =0.001), whereas it was not significantly increased in paternally inherited FH (SMR 1.30, 95% CI 0.65–2.32; p =0.234). Conclusion: Mortality rates are more increased when FH is inherited through the mother, supporting the fetal origin of adulthood disease hypothesis with all cause death, the most indisputable outcome measure. Future research should explore safe options for cholesterol-lowering therapy of pregnant women with FH in order to prevent unfavourable (epigenetic) consequences leading to atherosclerosis in their children. [Copyright &y& Elsevier]

Abstract: Objective: Mannose binding lectin (MBL) is one of the three initiators of complement activation. Polymorphisms of the MBL2 gene and its promoter, and especially haplotypes, determine MBL plasma levels. MBL deficiency has been associated with the development of atherosclerosis. We evaluated whether the rate of angiographic progression of coronary atherosclerosis during pravastatin treatment was associated with MBL2 haplotypes in REGRESS, a placebo-controlled 2 years intervention study. Methods: Three polymorphic sites in exon 1 (rs1800450, rs1800451 and rs5030737) of the MBL2 gene and 2 sites (rs7096206 and rs11003125) in the promoter region were genotyped in 398 subjects. Genotyping was performed using Applied Biosystems® TaqMan® Genotyping Assays. We divided the group in high, intermediate and low MBL2 secretor haplotypes. Quantitative coronary angiography was performed. Endpoints were mean segment diameter (MSD) and minimum obstruction diameter (MOD) established by quantitative coronary angiography. Results: At inclusion, 50.1, 31.7 and 17.6% of the patients in the REGRESS cohort carried the high, intermediate and low MBL2 secretor haplotypes, respectively. In 0.6% of the patients, the haplotype was not informative. There were no baseline differences between the MBL2 haplotypes for age, BMI, lipid levels, leukocyte counts, CRP, MSD and MOD. The intermediate MBL2 placebo group showed the greatest increase in MSD compared to the low MBL2 group (P =0.03). No difference was found for the change in MOD. No significant interaction between MBL2 haplotype groups and pravastatin therapy was observed. Conclusion: In men with proven coronary artery disease, MBL2 secretor haplotypes are not associated to the rate of progression of coronary sclerosis nor does pravastatin treatment influence progression based on MBL2 haplotypes. [Copyright &y& Elsevier]

Abstract: Background: Tendon xanthomas are characteristic for familial hypercholesterolemia (FH), and are associated with a higher risk of coronary heart disease (CHD). They often present with local inflammation. Inflammation may therefore be involved in their pathogenesis, as it is in the pathogenesis of CHD. A key role in the inflammatory pathway is played by the 5-lipoxygenase activating protein (ALOX5AP), which is known to influence the risk of CHD in FH. To test our hypothesis that ALOX5AP contributes to the development of xanthomas, we studied whether variants in the ALOX5AP gene influence the risk of xanthomas. Methods: We examined 945 patients with genetically confirmed heterozygous FH to determine whether they had tendon xanthomas. We genotyped seven polymorphisms in the ALOX5AP gene and constructed haplotypes of these polymorphisms. Results: The A allele of the rs9551963 polymorphism was associated with an increased risk of xanthomas (OR 1.52, 95% CI 1.11–2.07, p =0.01), while the A allele of rs17222842 was protective (OR 0.62, 95% CI 0.43–0.90, p =0.01). These two polymorphisms fully explained the risk estimates of all haplotypes. Individual haplotypes, however, were not significantly associated with xanthomas. Conclusion: Variants in the ALOX5AP gene are associated with the presence of xanthomas in FH patients. This result supports our hypothesis that inflammation is a pathogenetic factor of xanthomas. [Copyright &y& Elsevier]

Abstract: Objectives: To investigate the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene as a potential modifier gene for coronary heart disease (CHD) in patients with familial hypercholesterolemia (FH). Background: The ALOX5AP gene is required for the synthesis of leukotrienes, a protein family involved in inflammatory responses. Recently, genetic variation in this gene was shown to be associated with myocardial infarction in an Icelandic and British population. Since FH is characterized by severely increased levels of plasma low-density lipoprotein (LDL) cholesterol levels, chronic inflammation of the arterial wall, and subsequent premature CHD, the ALOX5AP gene could be an important modifier gene for CHD in FH. Methods: In a cohort of 1817 FH patients, we reconstructed two four-marker haplotypes, previously defined in Icelandic (HapA) and British (HapB) individuals. The haplotypes were inferred with PHASE and the associations between the haplotypes and CHD were analyzed with a Cox proportional hazards model, adjusted for year of birth, sex, and smoking. Results: HapB had a frequency of 6.9% and 8.2% in the group without and with CHD, respectively, conferring a hazard ratio of 1.48 (95% CI 1.17–1.89, p =0.001). This association was predominantly found in patients with LDL cholesterol levels above the median (HR 1.82, 95% CI 1.20–2.76, p =0.005). HapA was not associated with CHD. Conclusion: We conclude that genetic variation in the ALOX5AP gene contributes to CHD risk in patients with FH. Our findings emphasize the important role of inflammation in the pathogenesis of early CHD in this disorder, particularly in patients with more severely raised LDL cholesterol levels. [Copyright &y& Elsevier]

Homozygous familial hypercholesterolemia (hoFH) is caused by mutations in the low-density lipoprotein receptor gene and is characterized by severe hypercholesterolemia from birth and onset of premature cardiovascular disease (CVD) during childhood. The onset and progression of CVD using currently available testing methods in children with hoFH have not been fully characterized. A large cohort of patients with hoFH referred to our subspecialty clinic was studied. Thirty-nine patients (22 aged ≤16 years) underwent extensive cardiovascular, lipid, and genetic evaluation. Sixteen children ≤16 years without known CVD when first evaluated were followed up longitudinally for up to 8 years. CVD was clinically evident in 88% of subjects aged >16 years and 9% of those ≤16 years. Markers of atherosclerosis correlated significantly with age at which lipid-lowering treatment was initiated (abnormal coronary angiogram, abnormal aortic valve using echocardiography, and high calcium score using electron beam computed tomography; all p <0.01; abnormal carotid Doppler result; p = 0.03). Twenty of 22 children had no clinical evidence of coronary artery disease, yet 7 of these children had angiographically confirmed mild coronary artery disease (<50%) and 8 had mild to moderate aortic regurgitation using echocardiography. Of noninvasive tests, only evaluation of aortic valve regurgitation using echocardiography predicted the presence of angiographic coronary stenosis (p <0.001). During follow-up, 7 children developed progression of coronary and/or aortic valvular disease during their teenage years and 4 required surgical interventions. In conclusion, in these patients aggressive lipid-lowering treatment initiated in early childhood is warranted. Careful coronary and valvular surveillance strategies and coronary revascularization when appropriate are also warranted in this high-risk population. [Copyright &y& Elsevier]

Abstract: Studies on the clinical consequences of different low-density lipoprotein (LDL) receptor genotypes in adult patients have yielded conflicting results. We hypothesized that children with familial hypercholesterolemia (FH) provide a better model to perform genotype–phenotype analyses than adults. We tested this hypothesis and assessed the effect of LDL receptor genotypes on lipoprotein levels and on parental risk of cardiovascular disease (CVD) in a pediatric FH cohort. We identified 75 different LDL receptor mutations in 645 children with heterozygous FH; in these children, null alleles were clearly associated with more elevated LDL cholesterol levels compared to receptor-defective mutations. Familial factors explained 50.4% of the variation in LDL cholesterol levels of this pediatric cohort compared to only 9.5% in adults. Parental CVD risk was not significantly different between carriers of null alleles and receptor-defective mutations (RR, 1.22; 95% CI, 0.76–1.95; p =0.4). The N543H/2393del9 mutation was associated with a less deteriorated lipid profile and the parents had less often CVD relative to parents with other mutations (RR, 0.39; 95% CI, 0.20–0.78; p =0.008). We could confirm that children with FH provide a better model to perform genotype–phenotype analyses. In particular, children with null alleles had significantly more elevated LDL cholesterol levels than carriers of other alleles but this was not associated with higher risk of CVD in the parents. Nonetheless, a specific LDL receptor mutation was associated with less deteriorated lipoprotein levels and a milder CVD risk. [Copyright &y& Elsevier]