BIO FOr CARE: biomarkers of hypertrophic cardiomyopathy development and progression in carriers of Dutch founder truncating MYBPC3 variants-design and status.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is the most prevalent monogenic heart disease, commonly caused by truncating variants in the MYBPC3 gene. HCM is an important cause of sudden cardiac death; however, overall prognosis is good and penetrance in genotype-positive individuals is incomplete. The underlying mechanisms are poorly understood and risk stratification remains limited. AIM: To create a nationwide cohort of carriers of truncating MYBPC3 variants for identification of predictive biomarkers for HCM development and progression. METHODS: In the multicentre, observational BIO FOr CARe (Identification of BIOmarkers of hypertrophic cardiomyopathy development and progression in Dutch MYBPC3 FOunder variant CARriers) cohort, carriers of the c.2373dupG, c.2827C > T, c.2864_2865delCT and c.3776delA MYBPC3 variants are included and prospectively undergo longitudinal blood collection. Clinical data are collected from first presentation onwards. The primary outcome constitutes a composite endpoint of HCM progression (maximum wall thickness ≥ 20 mm, septal reduction therapy, heart failure occurrence, sustained ventricular arrhythmia and sudden cardiac death). RESULTS: So far, 250 subjects (median age 54.9 years (interquartile range 43.3, 66.6), 54.8% male) have been included. HCM was diagnosed in 169 subjects and dilated cardiomyopathy in 4. The primary outcome was met in 115 subjects. Blood samples were collected from 131 subjects. CONCLUSION: BIO FOr CARe is a genetically homogeneous, phenotypically heterogeneous cohort incorporating a clinical data registry and longitudinal blood collection. This provides a unique opportunity to study biomarkers for HCM development and prognosis. The established infrastructure can be extended to study other genetic variants. Other centres are invited to join our consortium.

UNRAVEL: big data analytics research data platform to improve care of patients with cardiomyopathies using routine electronic health records and standardised biobanking.

INTRODUCTION: Despite major advances in our understanding of genetic cardiomyopathies, they remain the leading cause of premature sudden cardiac death and end-stage heart failure in persons under the age of 60 years. Integrated research databases based on a large number of patients may provide a scaffold for future research. Using routine electronic health records and standardised biobanking, big data analysis on a larger number of patients and investigations are possible. In this article, we describe the UNRAVEL research data platform embedded in routine practice to facilitate research in genetic cardiomyopathies. DESIGN: Eligible participants with proven or suspected cardiac disease and their relatives are asked for permission to use their data and to draw blood for biobanking. Routinely collected clinical data are included in a research database by weekly extraction. A text-mining tool has been developed to enrich UNRAVEL with unstructured data in clinical notes. PRELIMINARY RESULTS: Thus far, 828 individuals with a median age of 57 years have been included, 58% of whom are male. All data are captured in a temporal sequence amounting to a total of 18,565 electrocardiograms, 3619 echocardiograms, data from over 20,000 radiological examinations and 650,000 individual laboratory measurements. CONCLUSION: Integration of routine electronic health care in a research data platform allows efficient data collection, including all investigations in chronological sequence. Trials embedded in the electronic health record are now possible, providing cost-effective ways to answer clinical questions. We explicitly welcome national and international collaboration and have provided our protocols and other materials on www.unravelrdp.nl .

Truncating Titin (TTN) Variants in Chemotherapy-Induced Cardiomyopathy.

Chemotherapy-induced cardiomyopathy (CCMP) is a complication of chemotherapy treatment occurring in 9% of patients treated with the use of anthracyclines. Currently, risk stratification is based on clinical risk factors that do not adequately account for variable individual susceptibility. This suggests the presence of other determinants. In this case series, we describe 2 women with breast cancer who developed severe heart failure within months after chemotherapy. Genetic screening revealed truncating frameshift mutations in TTN, encoding the myofilament titin, in both women. To our knowledge, this is the 1st report of an association between truncating TTN variants and CCMP. Because truncations in TTN are the most common cause of familial and sporadic dilated cardiomyopathy, further research is needed to establish their prevalence in patients presenting with CCMP.

Congenital posterior pole cataract and adult onset dilating cardiomyopathy: expanding the phenotype of αB-crystallinopathies.

Mutations in the αB-crystallin gene (CRYAB) have been reported in desmin-related myopathies, with or without cardiac involvement. Mutations in this gene have also been documented in large multi-generation families with autosomal dominant congenital posterior pole cataract (CPPC). In these congenital cataract families no cardiac or muscular phenotype was reported. This report describes a family with an unusual read-through mutation in CRYAB, leading to the elongation of the normal αB-crystallin protein with 19 amino acid residues. Affected family members combine a CPPC with an adult onset dilated cardiomyopathy (DCM), thereby expanding the αB-crystallinopathy phenotype. Repolarisation abnormalities preceded the onset of cardiomyopathy and were already present in childhood. No skeletal myopathy was observed. This report illustrates that congenital cataract can be a prelude to more severe disease even outside the context of inborn errors of metabolism. The identification of a CRYAB mutation in this family supports the notion that mutations in this gene are a rare cause of genetically determined DCM. The combined congenital cataract/cardiomyopathy phenotype adds to our understanding of the complex phenotypic spectrum of αB-crystallinopathies.

Arrhythmogenic cardiomyopathy: diagnosis, genetic background, and risk management.

Arrhythmogenic cardiomyopathy (AC), also known as arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), is a hereditary disease characterised by ventricular arrhythmias, right ventricular and/or left ventricular dysfunction, and fibrofatty replacement of cardiomyocytes. Patients with AC typically present between the second and the fourth decade of life with ventricular tachycardias. However, sudden cardiac death (SCD) may be the first manifestation, often at young age in the concealed stage of disease. AC is diagnosed by a set of clinically applicable criteria defined by an international Task Force. The current Task Force Criteria are the essential standard for a correct diagnosis in individuals suspected of AC. The genetic substrate for AC is predominantly identified in genes encoding desmosomal proteins. In a minority of patients a non-desmosomal mutation predisposes to the phenotype. Risk stratification in AC is imperfect at present. Genotype-phenotype correlation analysis may provide more insight into risk profiles of index patients and family members. In addition to symptomatic treatment, prevention of SCD is the most important therapeutic goal in AC. Therapeutic options in symptomatic patients include antiarrhythmic drugs, catheter ablation, and ICD implantation. Furthermore, patients with AC and also all pathogenic mutation carriers should be advised against practising competitive and endurance sports.

Detection of genomic deletions of PKP2 in arrhythmogenic right ventricular cardiomyopathy.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited myocardial disease that predominantly affects the right ventricle and is associated with ventricular arrhythmias that may lead to sudden cardiac death. Mutations within at least seven separate genes have been identified to cause ARVC, however a genetic culprit remains elusive in approximately 50% of cases. Although negative genetic testing may be secondary to pathogenic mutations within undiscovered genes, an alternative explanation may be the presence of large deletions or duplications involving known genes. These large copy number variants may not be detected with standard clinical genetic testing which is presently limited to direct DNA sequencing. We describe two cases of ARVC possessing large deletions involving plakophilin-2 (PKP2) identified with microarray analysis and/or multiplex ligation-dependent probe amplification (MLPA) that would have been classified as genotype negative with standard clinical genetic testing. A deletion of the entire coding region of PKP2 excluding exon 1 was identified in patient 1 and his son. In patient 2, MLPA analysis of PKP2 revealed deletion of the entire gene with subsequent microarray analysis demonstrating a de novo 7.9 Mb deletion of chromosome 12p12.1p11.1. These findings support screening for large copy number variants in clinically suspected ARVC cases without clear disease causing mutations following initial sequencing analysis.

Prenatal ultrasound diagnosis of MYH7 non-compaction cardiomyopathy.

We report on two prenatal ultrasound diagnoses of left ventricular non-compaction cardiomyopathy (LVNC) associated with mutation of the cardiac ß-myosin heavy chain gene (MYH7). LVNC is characterized by a trabecular meshwork and deep intertrabecular myocardial recesses communicating with the left ventricular cavity. Clinical features range from non-penetrant disease in adult carriers to heart failure, arrhythmia and thromboembolism. Both cases showed cardiomegaly on prenatal ultrasound examinations, with features indicating non-compaction of the myocardium apparent in the third trimester. Mutations in the MYH7 gene were identified postnatally in each case in both the proband and the father. One infant underwent surgical mitral valvuloplasty and a mechanical valve implant later; in the other, left ventricular function was unimpaired at birth. Cardiac function in both cases remained stable at last follow-up. These cases highlight the importance of prenatal ultrasound diagnosis of LVNC and the need for cardiologic and molecular testing of first-degree relatives who may be unknown carriers of an MYH7 mutation.

Circulating Acylcarnitines Associated with Hypertrophic Cardiomyopathy Severity: an Exploratory Cross-Sectional Study in MYBPC3 Founder Variant Carriers.

Hypertrophic cardiomyopathy (HCM) is a relatively common genetic heart disease characterised by myocardial hypertrophy. HCM can cause outflow tract obstruction, sudden cardiac death and heart failure, but severity is highly variable. In this exploratory cross-sectional study, circulating acylcarnitines were assessed as potential biomarkers in 124 MYBPC3 founder variant carriers (59 with severe HCM, 26 with mild HCM and 39 phenotype-negative [G + P-]). Elastic net logistic regression identified eight acylcarnitines associated with HCM severity. C3, C4, C6-DC, C8:1, C16, C18 and C18:2 were significantly increased in severe HCM compared to G + P-, and C3, C6-DC, C8:1 and C18 in mild HCM compared to G + P-. In multivariable linear regression, C6-DC and C8:1 correlated to log-transformed maximum wall thickness (coefficient 5.01, p = 0.005 and coefficient 0.803, p = 0.007, respectively), and C6-DC to log-transformed ejection fraction (coefficient -2.50, p = 0.004). Acylcarnitines seem promising biomarkers for HCM severity, however prospective studies are required to determine their prognostic value.

Cloning of murine TCF-1, a T cell-specific transcription factor interacting with functional motifs in the CD3-epsilon and T cell receptor alpha enhancers.

CD3-epsilon gene expression is confined to the T cell lineage. We have recently identified and cloned a human transcription factor, TCF-1, that binds to a functional element in the T lymphocyte-specific enhancer of CD3-epsilon. In a panel of human cell lines, TCF-1 expression was restricted to T lineage cells. TCF-1 belonged to a novel family of genes that contain the so-called high mobility group 1 (HMG) box. Here we report the cloning of murine TCF-1. Two splice alternatives were identified that were not previously observed in human TCF-1. Murine and human TCF-1 displayed a 95.5% overall amino acid homology. Recombinant murine and human TCF-1 recognized the same sequence motif in the CD3-epsilon enhancer as judged by gel retardation and methylation interference assays. With the murine cDNA clones several aspects of TCF-1 were analyzed. First, deletion analysis revealed that a region of TCF-1 containing the HMG box was sufficient for sequence-specific binding. Second, by high stringency Northern blotting and in situ hybridization, TCF-1 expression was shown to be confined to the thymus and to the T cell areas of the spleen. Third, TCF-1 bound specifically to a functional T cell-specific element in the T cell receptor alpha (TCR-alpha) enhancer. The T lineage-specific expression and the affinity for functional motifs in the TCR-alpha and CD3-epsilon enhancers imply an important role for TCF-1 in the establishment of the mature T cell phenotype.

A decade of genetic counseling in frontotemporal dementia affected families: few counseling requests and much familial opposition to testing.

A decade of genetic counseling of frontotemporal dementia (FTD) affected families has generated two important observations. First, the uptake rate for presymptomatic testing for FTD is low in our department of Clinical Genetics at the Erasmus Medical Center in the Netherlands. Second, FTD at-risk counselees reported substantial familial opposition to genetic testing, which is distinct from the attitude in Huntington Disease affected families. We hypothesize that the low acceptance for FTD genetic counseling is consequential to the familial opposition and explain this within the theoretical framework of separation-individuation. Furthermore, we hypothesize that separation-individuation problems do not similarly influence the acceptance of HD genetic counseling, due to the educative role of the well-organised patient organization for HD in the Netherlands. We offer counseling recommendations that serve to facilitate the individuation of the counselee with respect to the FTD genetic test.

A high incidence of MSH6 mutations in Amsterdam criteria II-negative families tested in a diagnostic setting.

BACKGROUND AND AIMS: In Lynch syndrome, the clinical phenotype in MSH6 mutation families differs from that in MLH1 and MSH2 families. Therefore, MSH6 mutation families are less likely to fulfil diagnostic criteria such as the Amsterdam II criteria (AC II) and the revised Bethesda guidelines (rBG), and will be underdiagnosed. The aim of the present study was to evaluate the contribution of MSH6 gene mutations in families that were analysed for Lynch syndrome in a diagnostic setting. METHODS: Families that had molecular analysis for Lynch syndrome were included in this study. Complete molecular screening of the MLH1, MSH2 and MSH6 genes was performed in all families. Microsatellite instability (MSI) and immunohistochemical (IHC) analysis was performed in almost all families. Clinical data were collected from medical records and family pedigrees. RESULTS: A total of 108 families were included. MSI and IHC analysis was performed in 97 families, and in 40 an MSI-high phenotype with absent protein expression was found. Germline mutation analysis detected mutations in 23 families (7 MLH1, 4 MSH2 and 12 MSH6). The majority of MSH6 families were AC II negative, but fulfilled the rBG. CONCLUSIONS: There is a high incidence of MSH6 mutations in families tested for Lynch syndrome in a diagnostic setting. Many of these families remain underdiagnosed using the AC II. The rBG are more useful to select these families for further analysis. However, to optimise the detection of MSH6 families, MSI and IHC analysis should also be performed in families with clustering of late-onset endometrial carcinoma.

Familial screening and genetic counselling in hypertrophic cardiomyopathy: the Rotterdam experience.

Hypertrophic cardiomyopathy (HCM) is a disease characterised by unexplained left ventricular hypertrophy (LVH) (i.e. LVH in the absence of another cardiac or systemic disease that could produce a similar degree of hypertrophy), electrical instability and sudden death (SD).Germline mutations in genes encoding for sarcomere proteins are found in more than half of the cases of unexplained LVH. The autosomal dominant inherited forms of HCM are characterised by incomplete penetrance and variability in clinical and echocardiographic features, prognosis and therapeutic modalities. The identification of the genetic defect in one of the HCM genes allows accurate presymptomatic detection of mutation carriers in a family. Cardiac evaluation of at-risk relatives enables early diagnosis and identification of those patients at high risk for SD, which can be the first manifestation of the disease in asymptomatic persons.In this article we present our experience with genetic testing and cardiac screening in our HCM population and give an overview of the current literature available on this subject. (Neth Heart J 2007;15:184-9.).

Base J originally found in kinetoplastida is also a minor constituent of nuclear DNA of Euglena gracilis.

We have analyzed DNA of EUGLENA: gracilis for the presence of the unusual minor base beta-D-glucosyl-hydroxymethyluracil or J, thus far only found in kinetoplastid flagellates and in DIPLONEMA: Using antibodies specific for J and post-labeling of DNA digests followed by two-dimensional thin-layer chromatography of labeled nucleotides, we show that approximately 0.2 mole percent of EUGLENA: DNA consists of J, an amount similar to that found in DNA of Trypanosoma brucei. By staining permeabilized EUGLENA: cells with anti-J antibodies, we show that J is rather uniformly distributed in the EUGLENA: nucleus, and does not co-localize to a substantial extent with (GGGTTA)(n) repeats, the putative telomeric repeats of EUGLENA: Hence, most of J in EUGLENA: appears to be non-telomeric. Our results add to the existing evidence for a close phylogenetic relation between kinetoplastids and euglenids.

Hyperechogenic fetal bowel: counseling difficulties.

The detection of echodense fetal bowel on ultrasound examination in the second trimester of pregnancy justifies invasive procedures such as amniocentesis to detect an underlying cause. We present a case in which initial tests identified only one mutation in the cystic fibrosis transmembrane regulator (CFTR)-gene of the fetus, the family history being negative for CF. Strongly reduced intestinal enzyme activities suggested intestinal obstruction and further increased the estimated risk for CF. After the 24th gestational week, a second mutation was found, confirming cystic fibrosis in this child. Problems in counseling in this particular case are discussed.

Spinocerebellar ataxias in the Netherlands: prevalence and age at onset variance analysis.

BACKGROUND: International prevalence estimates of autosomal dominant cerebellar ataxias (ADCA) vary from 0.3 to 2.0 per 100,000. The prevalence of ADCA in the Netherlands is unknown. Fifteen genetic loci have been identified (SCA-1-8, SCA-10-14, SCA-16, and SCA-17) and nine of the corresponding genes have been cloned. In SCA-1, SCA2, SCA3, SCA6, SCA7, SCA-12 and SCA-17 the mutation has been shown to be an expanded CAG repeat. Previously, the length of the CAG repeat was found to account for 50 to 80% of variance in age at onset. Because of heterogeneity in encoded proteins, different pathophysiologic mechanisms leading to neurodegeneration could be involved. The relationship between CAG repeat length and age at onset would then differ accordingly. METHOD: Based on the results of SCA mutation analysis in the three DNA diagnostic laboratories that serve the entire Dutch population, the authors surveyed the number of families and affected individuals per SCA gene, as well as individual repeat length and age at onset. Regression analysis was applied to study the relationship between CAG repeat length and age at onset per SCA gene. The slopes of the different regression curves were compared. RESULTS: On November 1, 2000, mutations were found in 145 ADCA families and 391 affected individuals were identified. The authors extrapolated a minimal prevalence of 3.0 per 100,000 (range 2.8 to 3.8/100,000). SCA3 was the most frequent mutation. CAG repeat length contributed to 52 to 76% of age at onset variance. Regression curve slopes for SCA-1, SCA2, SCA3, and SCA7 did not differ significantly. CONCLUSIONS: The estimated minimal prevalence of ADCA in the Netherlands is 3.0 per 100,000 inhabitants. Except for SCA6, the relationship between age at onset and CAG repeat expansion does not differ significantly between SCA-1, SCA2, SCA3, and SCA7 patient groups in our population, indicating that these SCA subtypes share similar mechanisms of polyglutamine-induced neurotoxicity, despite heterogeneity in gene products.

Control of gene expression during lymphoid development: targeted gene disruption provides new clues.

The expression of structural genes is thought to be regulated by DNA-binding factors interacting with cis-acting regulatory elements. These regulatory elements, identified for many lymphopoietic genes, have served in recent years to identify and clone novel transcription factors. The expression of some of these factors is found to be confined to the lymphoid lineage. This regulated expression in both time and space is thought to mediate entry into and progression along the correct developmental differentiation programs. In recent years, many laboratories have tried to assess the functional relevance of these DNA-binding factors by making use of gene targeting techniques. A review of the results of such knock-out experiments and the consequences for lymphoid development models appears below.

[From gene to disease: arteriohepatic dysplasia or Alagille syndrome]. / Van gen naar ziekte; arteriohepatische dysplasie--het syndroom van Alagille.

Alagille syndrome (AGS), also known as arteriohepatic dysplasia, is an autosomal dominant disorder with a prevalence of approximately one in 70,000 live births. AGS is characterised by intrahepatic bile duct paucity and other developmental abnormalities affecting the heart, liver, eyes, vertebrae and the craniofacial region. Mutations in the JAG1 gene have been demonstrated to cause Alagille syndrome. JAG1 encodes a cellular membrane-bound ligand for the Notch receptor and is expressed during the normal development of tissues affected in Alagille syndrome. JAG1 mutations are detected in approximately 70% of AGS patients and are mostly protein truncating mutations. JAG1 mutations have also been described in patients that do not demonstrate the complete AGS phenotype, suggesting that the phenotypic spectrum of JAG1 mutations is broader than thus far assumed.

[From gene to disease; neurofibromatosis type 1]. / Van gen naar ziekte; neurofibromatosis type 1.

Neurofibromatosis type 1 (NF1) is an autosomal dominant disease characterised by café-au-lait spots, freckling in the axillary or inguinal region, dermal and plexiform neurofibromas and Lisch nodules. Complications are severe in one third of patients, and the clinical variability is pronounced, even within families. The NF1 gene has been localised to chromosome 17q11.2 and encodes the protein neurofibromin. The gene is proposed to be a tumour suppressor gene. Inactivation of neurofibromin leads to a disruption in cell growth regulation. Mutation analysis is possible but laborious, and therefore NF1 is generally a clinical diagnosis based on diagnostic criteria.