The prevalence of familial hyperaldosteronism in apparently sporadic primary aldosteronism in Germany: a single center experience

Primary aldosteronism (PA) is the most frequent cause of secondary arterial hypertension. To date 3 forms of familial hyperaldosteronism (FH) have been described accounting for a small percentage of all PA cases. In Germany, the prevalence of FH is currently unknown. Our aim was to determine the prevalence of familiarity in a large cohort of patients with PA. A total of 166 patients with apparently sporadic PA in Munich were investigated. FH types I, II, and III were identified using established clinical, biochemical, and molecular criteria. Among the 166 patients with PA, 2 patients (1.2%) reported a family history suggestive of FH. None of the 166 patients showed clinical, endocrine, or genetic evidence of FH type I. The 2 families had characteristic features of FH type II. Family A had 3 subjects affected out of 11 evaluated family members. Family B had 3 out of 4. Bilateral adrenal hyperplasia and unilateral adrenal adenoma were found within the same family. FH type I and FH type III are rare in Germany. With a prevalence of 1.2%, FH type II seems to be more common in apparently sporadic PA than had been assumed so far.     

Novel and recurrent LDLR gene mutations in Pakistani hypercholesterolemia patients

The majority of patients with the autosomal dominant disorder familial hypercholesterolemia (FH) carry novel mutations in the low density lipoprotein receptor (LDLR) that is involved in cholesterol regulation. In different populations the spectrum of mutations identified is quite different and to date there have been only a few reports of the spectrum of mutations in FH patients from Pakistan. In order to identify the causative LDLR variants the gene was sequenced in a Pakistani FH family, while high resolution melting analysis followed by sequencing was performed in a panel of 27 unrelated sporadic hypercholesterolemia patients. In the family a novel missense variant (c.1916T > G, p.(V639G)) in exon 13 of LDLR was identified in the proband. The segregation of the identified nucleotide change in the family and carrier status screening in a group of 100 healthy subjects was done using restriction fragment length polymorphism analysis. All affected members of the FH family carried the variant and none of the non-affected members nor any of the healthy subjects. In one of the sporadic cases, two sequence changes were detected in exon 9, one of these was a recurrent missense variant (c.1211C > T; p.T404I), while the other was a novel substitution mutation (c.1214 A > C; N405T). In order to define the allelic status of this double heterozygous individual, PCR amplified fragments were cloned and sequenced, which identified that both changes occurred on the same allele. In silico tools (PolyPhen and SIFT) were used to predict the effect of the variants on the protein structure, which predicted both of these variants to have deleterious effect. These findings support the view that there will be a novel spectrum of mutations causing FH in patients with hypercholesterolaemia from Pakistan.     

Difference in Aneurysm Characteristics between Patients with Familial and Sporadic Aneurysmal Subarachnoid Haemorrhage

ObjectPatients with familial intracranial aneurysms (IA) have a higher risk of rupture than patients with sporadic IA. We compared geometric and morphological risk factors for aneurysmal rupture between patients with familial and sporadic aneurysmal subarachnoid hemorrhage (aSAH) to analyse if these risk factors contribute to the increased rupture rate of familial IA.MethodsGeometric and morphological aneurysm characteristics were studied on CT-angiography in a prospectively collected series of patients with familial and sporadic aSAH, admitted between September 2006 and September 2009, and additional patients with familial aSAH retrieved from the prospectively collected database of familial IA patients of our center. Odds ratios (OR) with corresponding 95% confidence intervals (95% CI) were calculated to compare the aneurysm characteristics between patients with familial and sporadic aSAH.ResultsWe studied 67 patients with familial and 184 with sporadic aSAH. OR’s for familial compared with sporadic aSAH were for oval shape 1.16(95%CI:0.65–2.09), oblong shape 0.26(95%CI:0.03–2.13), irregular shape 0.83(95%CI:0.47–1.49), aspect ratio ≥ 1.6 0.94(95%CI:0.54–1.66), contact with the perianeurysmal environment (PAE) 1.15(95%CI:0.56–2.40), deformation by the PAE 1.05(95%CI:0.47–2.35) and for dominance of the posterior communicating artery (PCoA) in case of PCoA aneurysms 1.97(95% CI:0.50–7.83).ConclusionsThe geometric and morphological risk factors for aneurysm rupture do not have a higher prevalence in familial than in sporadic aSAH and thus do not explain the increased risk of IA rupture in patients with familial IA. We recommend further search for other potential risk factors for rupture of familial IA, such as genetic factors.     

Cutting edge: localization of the host recognition functions of complement factor H at the carboxyl-terminal: implications for hemolytic uremic syndrome

Incidents of hemolytic uremic syndrome (HUS) include a subset of patients that exhibit mutations in C factor H. These mutations cluster in the C-terminal domains of factor H where previous reports have identified polyanion and C3b-binding sites. In this study, we show that recombinant human factor H with deletions at the C-terminal end of the protein loses the ability to control the spontaneous activation of the alternative C pathway on host-like surfaces. For the pathology of HUS, the findings imply that mutations that disrupt the normal functions of the C-terminal domains prevent host polyanion recognition. The resulting uncontrolled activation of complement on susceptible host tissues appears to be the initiating event behind the acute renal failure of familial HUS patients.     

Association between serum sulfatide and carotid intima media thickness in patients with familial hypercholesterolemia

There is a positive association between sulfatide and atherosclerosis in an animal model for human familial hypercholesterolemia. Carotid intima–media thickness (IMT) is thought to be a marker of atherosclerosis in humans. We investigated the relationship between sulfatide and carotid IMT in heterozygous familial hypercholesterolemia (FH) patients. Thirty-five genetically-verified heterozygous patients with FH and 34 healthy controls were recruited into our study. We measured serum sulfatide levels, the carotid IMT, and conventional cardiovascular risk factors including obesity parameters, blood pressure, fasting blood glucose, and lipid profiles. Subjects with heterozygous FH had significantly elevated serum sulfatide, elevated total cholesterol, low-density lipoprotein cholesterol, and increased carotid IMT compared with control subjects. In patients with FH, univariate analysis showed that serum sulfatide was significantly correlated with carotid IMT. Multiple linear regression analysis indicated that serum sulfatide was the only independent predictor of carotid IMT in patients with FH. Patients with heterozygous FH had significantly higher carotid IMT and the level of serum sulfatide was independently associated with atherosclerotic progression. (R: 0.720, R²: 0.503, p?相似文献   

Tendon xanthomas in familial hypercholesterolemia are associated with a differential inflammatory response of macrophages to oxidized LDL

Tendon xanthomas (TX) are pathognomonic lipid deposits commonly found in familial hypercholesterolemia (FH) patients. The aim of this study was to determine whether macrophages from FH patients with TX (TX+) have higher predisposition to foam cells formation after oxidized LDL (oxLDL) overload than those from FH patients without TX (TX-), and if their differential gene expression profile could explain these different phenotypes. Total RNA pools from macrophages from FH patients TX+ and TX- were analyzed using Affymetrix oligonucleotide arrays to evaluate the gene expression profile in presence and absence of oxLDL. Also, the intracellular lipid content was measured by fluorescence flow cytometry. Results of these studies suggest that macrophages from FH subjects TX+ compared to those TX- have a differential response to oxLDL, since they show higher intracellular cholesterol ester accumulation and a differential gene expression profile. The gene array data were validated by relative quantitative real-time RT-PCR and quantitative ELISA in culture media and plasma samples. FH subjects TX+ showed increased plasma tryptase, TNF-alpha, IL-8 and IL-6 concentrations. We propose that TX formation are associated with higher intracellular lipid content, and higher inflammatory response of macrophages in response to oxLDL.     

HDL abnormalities in familial hypercholesterolemia: Focus on biological functions

Although a selective strong elevation in the plasma level of low-density lipoprotein (LDL) cholesterol is the hallmark of familial hypercholesterolemia (FH), also other plasma lipoprotein and lipid subspecies are changed in these patients. Several studies in FH patients have pointed to the qualitative abnormalities of high-density lipoprotein (HDL) particles, including their triglyceride and sphingomyelin enrichment, reduced capacity to promote cholesterol efflux from macrophages, impaired anti-inflammatory and anti-oxidant activities, and reduced plasma levels of miRs regulating HDL-dependent cholesterol efflux from macrophage foam cells, typical of atherosclerotic lesions. Thus, accurate understanding of HDL functionality and its disturbances in FH may serve a better estimation of the prognosis and also provide additional clues when searching for novel therapeutic choices in this disease. In spite of such a potential promise, there has been no prior comprehensive review focusing on indices of HDL function in FH patients. In the present review, we aim to fulfill this gap by identifying measures of HDL function that are impaired in FH, and by providing a concise summary on the impact of different lipid-modifying therapies on HDL functionality in FH.     

South African founder mutations in the low-density lipoprotein receptor gene causing familial hypercholesterolemia in the Dutch population

In South African Afrikaners, three point mutations in the gene coding for the low-density lipoprotein (LDL)-receptor are responsible for more than 95% of the cases of familial hypercholesterolemia (FH). To investigate whether one or more of these mutations originated in The Netherlands, a large group of Dutch heterozygous FH patients was screened for the presence of these three mutations. Of these, a missense mutation in exon 9 of the LDL-receptor gene, resulting in a substitution of Met for Val⁴⁰⁸, responsible for 15% of FH in Afrikaners, was found in 19 (1.5%) of 1268 FH patients of Dutch descent. Nine of the patients carrying the exon 9 mutation on one allele shared the LDL-receptor DNA haplotype with an FH patient from South Africa, who was homozygous for the same mutation. This would suggest that the mutation in these patients and in the South African patient have a common ancestral background. The remaining ten FH patients all shared a common haplotype, partly identical to the Afrikaner haplotype, which chould have arisen from a single recombinational event. This mutation has not been described in persons other than of Dutch ancestry and supports the hypothesis that this mutation in exon 9 originated in The Netherlands and, in all likelihood, was introduced into South Africa by early Dutch settlers in the seventeenth century.     

Shiga toxin-producing Escherichia coli O171:H25 strain isolated from a patient with haemolytic uraemic syndrome

Shiga toxin-producing Escherichia coli (STEC) strains of O157:H7 serotype are a predominant cause of haemolytic uraemic syndrome (HUS) worldwide, but strains of non-O157 serotypes can also be associated with serious disease. Some of them are associated with outbreaks of HUS, others with sporadic cases of HUS, and some with diarrhoea but not with outbreaks or HUS. A large number of STEC serotypes isolated from ruminants and foods have never been associated with human disease. In this study we characterize a STEC strain belonging to serotype O171:H25 that is responsible for a case of HUS. This strain has a single Shiga toxin gene encoding Stx2 toxin, and hlyA gene, but is eae-negative.     

Increased production of VLDL apoB-100 in subjects with familial hypercholesterolemia carrying the same null LDL receptor gene mutation

Early radiokinetic studies revealed that the classical metabolic defect in patients with familial hypercholesterolemia (FH) is hypocatabolism of LDL due to decreased LDL receptor activity. However, recent studies have suggested that hepatic oversecretion of apolipoprotein B-100 (apoB-100)-containing lipoproteins could also contribute to the markedly elevated plasma concentrations of LDL-cholesterol found in FH. The aim of this study was to examine the kinetics of apoB-100 labeled with a stable isotope (l-[5,5,5-D(3)] leucine) in five normolipidemic controls and in seven well-characterized FH subjects that included six FH heterozygotes and one FH homozygote carrying the same null LDL receptor gene mutation. As compared with controls, the VLDL apoB-100 production rate was increased by 50% in the FH heterozygotes and by 109% in the FH homozygote. Furthermore, FH subjects had significantly higher LDL apoB-100 pool size and lower LDL apoB-100 fractional catabolic rate than controls. These results indicate that the elevation of plasma LDL-cholesterol found in FH is attributable to both decreased clearance of LDL and increased hepatic production of apoB-100-containing lipoproteins.     

Identification of a deletion in the low density lipoprotein (LDL) receptor gene in a patient with familial hypercholesterolaemia

Summary DNA samples from 60 unrelated UK patients with familial hypercholesterolaemia (FH) were screened by Southern blot hybridisation to detect gross alterations in the low density lipoprotein (LDL) receptor gene. One patient was found to have a 2kb deletion in the 3 part of the gene. The deletion cosegregates with the FH phenotype in his family. This finding is compatible with the deletion being the cause of FH in this case and makes a presymptomatic test based on DNA analysis available for this family. The defects in most of the other patients are likely to be due to point mutations.     

Identification of a deletion in the LDL receptor gene A Finnish type of mutation

A cDNA probe for the low density lipoprotein (LDL) receptor gene was used to screen DNA samples from 52 unrelated Finnish patients with the heterozygous form of familial hypercholesterolemia (FH) and 51 healthy controls. Southern blot analysis using the restriction enzyme PvuII revealed an abnormal 11 kb (kilo base-pair) restriction fragment in 16 (31%) of the patients but none of the controls. A more detailed restriction enzyme analysis of the DNA from patients revealed a mutation which apparently is due to an 8 kb deletion extending from intron 15 to exon 18 of the LDL receptor gene. Co-segregation of FH with the mutated gene was demonstrated in three families. These data are consistent with a ‘founder gene effect’ and support the assumption that recombinant DNA methods may have great impact on the diagnostics of FH in genetically homogeneous populations.     

Multiplex ligation-dependent probe amplification of LDLR enhances molecular diagnosis of familial hypercholesterolemia

Autosomal dominant (AD) familial hypercholesterolemia [FH; Mendelian Inheritance in Man (MIM) 143890] typically results from mutations in the LDL receptor gene (LDLR), which are now commonly diagnosed using exon-by-exon screening methods, such as exon-by-exon sequence analysis (EBESA) of genomic DNA (gDNA). However, many patients with FH have no LDLR mutation identified by this method. Part of the diagnostic gap is attributable to the genetic heterogeneity of AD FH, but another possible explanation is inadequate sensitivity of EBESA to detect certain mutation types, such as large deletions or insertions in LDLR. Multiplex ligation-dependent probe amplification (MLPA) is a new method that detects larger gDNA alterations that are overlooked by EBESA. We hypothesized that some FH patients with no LDLR mutation detectable by EBESA would have an abnormal LDLR MLPA pattern. In 70 unrelated FH patients, 44 had LDLR mutations detected by EBESA, including missense, RNA splicing, nonsense, or small deletion mutations, and 5 had the APOB R3500Q mutation. Among the remaining 21 AD FH patients with no apparent LDLR mutation, we found abnormal LDLR MLPA patterns in 12 and then demonstrated the deleted sequence in 5 of these. These findings indicate that MLPA may be a useful new adjunctive tool for the molecular diagnosis of FH.     

Population-based risk estimates of Wilms tumor in sporadic aniridia. A comprehensive mutation screening procedure of PAX6 identifies 80% of mutations in aniridia

Aniridia is a severe eye disease characterized by iris hypoplasia; both sporadic cases and familial cases with an autosomal dominant inheritance exist. Mutations in the PAX6 gene have been shown to be the genetic cause of the disease. Some of the sporadic cases are caused by large chromosomal deletions, some of which also include the Wilms tumor gene (WAGR syndrome), resulting in an increased risk of developing Wilms tumor. Based on the unique registration of both cancer and aniridia cases in Denmark, we have made the most accurate risk estimate to date for Wilms tumor in sporadic aniridia. We have found that patients with sporadic aniridia have a relative risk of 67 (confidence interval: 8.1-241) of developing Wilms tumor. Among patients investigated for mutations, Wilms tumor developed in only two patients out of 5 with the Wilms tumor gene (WT1) deleted. None of the patients with smaller chromosomal deletions or intragenic mutations were found to develop Wilms tumor. Our observations suggest a smaller risk for Wilms tumor than previous estimates, and that tumor development requires deletion of WT1. We report a strategy for the mutational analysis of aniridia cases resulting in the detection of mutations in 68% of sporadic cases and 89% of familial cases. We also report four novel mutations in PAX6, and furthermore, we have discovered a new alternatively spliced form of PAX6.     

Determining and interpreting new predictive rules for breast cancer familial inheritance

DNA copy number alterations have been discovered to be key genetic events in development and progression of cancer. No clear data of familial and sporadic breast cancer are available. We focused on looking for an independent platform as a tool to identify the chromosomal profile in familial versus sporadic breast cancer patients. A total of 124 breast cancer patients were studied utilizing aCGH. The dataset was analyzed using Gaussian Mixture Models to determine the thresholds in order to assess gene copy number changes and to minimize the impact of noise on further data analyses. The identification of regions of consistent aberration across samples was carried out with statistical approaches and machine learning tools to draw profiles for familial and sporadic groups. Familial and sporadic cases resulted with a chromosome imbalance of 15% [false discovery rate (FDR): q=718E-5] and 18% (FDR: q=632E-13), respectively. The differential map evidenced two cytogenetic bands (8p23 and 11q13-11q14) significantly altered in familial versus sporadic cases (FDR: q=7E-4). The application of a new bioinformatics tool that discovers fuzzy classification rules (IFRAIS) let to individualize association of genes alterations that identify familial or sporadic cases. These results are comparable to those of the other systems used and are consistent from the biological point of view.     

The molecular basis of familial hypercholesterolemia in The Netherlands

Mutations in the low-density lipoprotein (LDL) receptor gene are responsible for familial hypercholesterolemia (FH). At present, more than 600 mutations in this gene are known to underlie FH. However, the array of mutations varies considerably in different populations. Therefore, the delineation of essentially all LDL-receptor gene mutations in a population is a prerequisite for the implementation of nation-wide genetic testing for FH. In the Netherlands, mutation analysis by denaturing gradient gel electrophoresis and sequencing in 1641 clinically diagnosed FH patients resulted in the characterization of 159 different LDL-receptor gene defects. The nine most common mutations were responsible for 66.5% of our FH index cases. Of these, four mutations occurred with relatively high frequencies in specific parts of the Netherlands. The remaining mutations were only encountered in single FH patients, comprising 22.2% of the patient cohort analyzed. Subsequent genetic testing of relatives of the index cases within the national FH screening program resulted in the identification of 5,531 FH patients in total. The analysis for LDL-receptor mutations is a continuing effort to update the LDL-receptor mutation catalogue. Subsequently, with the newly generated index cases, the screening program can be extended and continued to identify and treat FH patients as early as possible and reduce cardiovascular morbidity and mortality in these patients at high risk.     

Familial hypercholesterolemia in St. Petersburg: diversity of mutations argues against a strong founder effect

Examination of low-density lipoprotein (LDL) receptor, its promoter, and major exon-intron boundaries from a sample of patients with familial hypercholesterolemia (FH) from 74 probands of St. Petersburg revealed 34 mutations and 8 widely spread polymorphisms at this locus. Only four mutations were considered silent, while the other 30 are likely associated with familial hypercholesterolemia (FH). Mutations in the LDL receptor gene, inducing the disease, were identified in 41 (55%) out of 74 families with FH. Mutation R3500Q in apolipoprotein B (APOB) gene was not detected in all probands. Therefore in the families lacking mutations hypercholesterolemia was induced by mutations in the introns of the LDL receptor gene or by other genetic factors. Nineteen mutations causing disease progression were described in St. Petersburg for the first time, while 18 of them are specific for Russia. Among Ashkenazi Jews, major mutation G197del was detected in 30% (7 out of 22) of patients with FH. In the Slavic population of St. Petersburg, no major mutations were detected. Only five mutations were identified in two families, while 24 were found in isolated families. These data are indicative of the lack of a strong founder effect for FH in the St. Petersburg population.     

Low density lipoprotein receptor founder mutations in Afrikaner familial hypercholesterolaemic patients: a comparison of two geographical areas

Summary Afrikaners with familial hypercholesterolaemia (FH) were screened for the presence of three point mutations in the low density lipoprotein receptor gene that were previously described as being relatively common in this population. The prevalence and distribution of the mutations were compared in 27 unrelated homozygous and 79 unrelated heterozygous FH Afrikaner patients from two regions in South Africa, the Transvaal and Cape Provinces. The relative distribution of the three mutations was similar in the two regions, with the FH1 mutation being the most prevalent (66%), followed by the FH2 mutation (27%) and the FH3 mutation (7%). Interestingly, defects other than the three common mutations are more common in the Cape than in the Transvaal; thus the three known mutations account for 98% of FH alleles in the Transvaal and only 74% in the Cape Province. None of the patients carried the recently described familial defective apolipoprotein B100 mutation. These results establish that three founder mutant genes occur amongst the Afrikaner and are responsible for the overall high prevalence of FH in this population.     

Two partial deletion mutations involving the same Alu sequence within intron 8 of the LDL receptor gene in Korean patients with familial hypercholesterolemia

Twenty-eight unrelated persons heterozygous for familial hypercholesterolemia (FH) were screened to assess the frequency and nature of major structural rearrangements at the low-density lipoprotein (LDL) receptor gene in Korean FH patients. Genomic DNA was analyzed by Southern blot hybridization with probes encompassing exons 1–18 of the LDL receptor gene. Two different deletion mutations (FH29 and FH110) were detected in three FH patients (10.7%). Each of the mutations was characterized by the use of exon-specific probes and detailed restriction mapping mediated by long-PCR (polymerase chain reaction). Mutation FH29 was a 3.83-kb deletion extending from intron 6 to intron 8 and FH110 was a 5.71-kb deletion extending from intron 8 to intron 12. In FH29, the translational reading frame was preserved and the deducible result was a cysteine-rich A and B repeat truncated protein that might be unable to bind LDL but would continue to bind β-VLDL. FH110 is presumed to be a null allele, since the deletion shifts the reading frame and results in a truncated protein that terminates in exon 13. Sequence analysis revealed that both deletions have occurred between two Alu-repetitive sequences that are in the same orientation. This suggested that in these patients the deletions were caused by an unequal crossing over event following mispairing of two Alu sequences on different chromatids during meiosis. Moreover, in both deletions, the recombinations were related to an Alu sequence in intron 8 and the deletion breakpoints are found within a specific sequence, 27 bp in length. This supports the hypothesis that this region might have some intrinsic instability, and act as one of the important factors in large recombinational rearrangements. Received: 3 April 1996 / Revised: 19 August 1996