Large- and medium-sized arterial aneurysms in two patients with SMAD4-related juvenile polyposis syndrome.

Germline SMAD4 pathogenic variants (PVs) cause juvenile polyposis syndrome (JPS), which is known for an increased risk of gastrointestinal juvenile polyps and gastrointestinal cancer. Many patients with SMAD4 PV also show signs of hereditary hemorrhagic telangiectasia (HHT) and some patients have aneurysms and dissections of the thoracic aorta. Here we describe two patients with a germline SMAD4 PV and a remarkable clinical presentation including multiple medium-sized arterial aneurysms. More data are needed to confirm whether the more extensive vascular phenotype and the other described features in our patients are indeed part of a broader JPS spectrum.

Growth charts for Marfan syndrome in the Netherlands and analysis of genotype-phenotype relationships.

To optimize care for children with Marfan syndrome (MFS) in the Netherlands, Dutch MFS growth charts were constructed. Additionally, we aimed to investigate the effect of FBN1 variant type (haploinsufficiency [HI]/dominant negative [DN]) on growth, and compare MFS-related height increase across populations. Height and weight data of individuals with MFS aged 0-21 years were retrospectively collected. Generalized Additive Models for Location, Scale and Shape (GAMLSS) was used for growth chart modeling. To investigate genotype-phenotype relationships, FBN1 variant type was included as an independent variable in height-for-age and BMI-for-age models. MFS-related height increase was compared with that of previous MFS growth studies from the United States, Korea, and France. Height and weight data of 389 individuals with MFS were included (210 males). Height-for-age, BMI-for-age, and weight-for-height charts reflected the tall and slender MFS habitus throughout childhood. Mean increase in height of individuals with MFS compared with the general Dutch population was significantly lower than in the other three MFS populations compared to their reference populations. FBN1-HI variants were associated with taller height in both sexes, and decreased BMI in females (p-values <0.05). This Dutch MFS growth study broadens the notion that genetic background and MFS variant type (HI/DN) influence tall and slender stature in MFS.

Phenotypic spectrum of TGFB3 disease-causing variants in a Dutch-French cohort and first report of a homozygous patient.

Disease-causing variants in TGFB3 cause an autosomal dominant connective tissue disorder which is hard to phenotypically delineate because of the small number of identified cases. The purpose of this retrospective cross-sectional multicenter study is to elucidate the genotype and phenotype in an international cohort of TGFB3 patients. Eleven (eight novel) TGFB3 disease-causing variants were identified in 32 patients (17 families). Aortic root dilatation and mitral valve disease represented the most common cardiovascular findings, reported in 29% and 32% of patients, respectively. Dissection involving distal aortic segments occurred in two patients at age 50 and 52 years. A high frequency of systemic features (65% high-arched palate, 63% arachnodactyly, 57% pectus deformity, 52% joint hypermobility) was observed. In familial cases, incomplete penetrance and variable clinical expressivity were noted. Our cohort included the first described homozygous patient, who presented with a more severe phenotype compared to her heterozygous relatives. In conclusion, TGFB3 variants were associated with a high percentage of systemic features and aortic disease (dilatation/dissection) in 35% of patients. No deaths occurred from cardiovascular events or pregnancy-related complications. Nevertheless, homozygosity may be driving a more severe phenotype.

Results of next-generation sequencing gene panel diagnostics including copy-number variation analysis in 810 patients suspected of heritable thoracic aortic disorders.

Simultaneous analysis of multiple genes using next-generation sequencing (NGS) technology has become widely available. Copy-number variations (CNVs) in disease-associated genes have emerged as a cause for several hereditary disorders. CNVs are, however, not routinely detected using NGS analysis. The aim of this study was to assess the diagnostic yield and the prevalence of CNVs using our panel of Hereditary Thoracic Aortic Disease (H-TAD)-associated genes. Eight hundred ten patients suspected of H-TAD were analyzed by targeted NGS analysis of 21 H-TAD associated genes. In addition, the eXome hidden Markov model (XHMM; an algorithm to identify CNVs in targeted NGS data) was used to detect CNVs in these genes. A pathogenic or likely pathogenic variant was found in 66 of 810 patients (8.1%). Of these 66 pathogenic or likely pathogenic variants, six (9.1%) were CNVs not detectable by routine NGS analysis. These CNVs were four intragenic (multi-)exon deletions in MYLK, TGFB2, SMAD3, and PRKG1, respectively. In addition, a large duplication including NOTCH1 and a large deletion encompassing SCARF2 were detected. As confirmed by additional analyses, both CNVs indicated larger chromosomal abnormalities, which could explain the phenotype in both patients. Given the clinical relevance of the identification of a genetic cause, CNV analysis using a method such as XHMM should be incorporated into the clinical diagnostic care for H-TAD patients.

A mutation in C2orf64 causes impaired cytochrome c oxidase assembly and mitochondrial cardiomyopathy.

The assembly of mitochondrial respiratory chain complex IV (cytochrome c oxidase) involves the coordinated action of several assembly chaperones. In Saccharomyces cerevisiae, at least 30 different assembly chaperones have been identified. To date, pathogenic mutations leading to a mitochondrial disorder have been identified in only seven of the corresponding human genes. One of the genes for which the relevance to human pathology is unknown is C2orf64, an ortholog of the S. cerevisiae gene PET191. This gene has previously been shown to be a complex IV assembly factor in yeast, although its exact role is still unknown. Previous research in a large cohort of complex IV deficient patients did not support an etiological role of C2orf64 in complex IV deficiency. In this report, a homozygous mutation in C2orf64 is described in two siblings affected by fatal neonatal cardiomyopathy. Pathogenicity of the mutation is supported by the results of a complementation experiment, showing that complex IV activity can be fully restored by retroviral transduction of wild-type C2orf64 in patient-derived fibroblasts. Detailed analysis of complex IV assembly intermediates in patient fibroblasts by 2D-BN PAGE revealed the accumulation of a small assembly intermediate containing subunit COX1 but not the COX2, COX4, or COX5b subunits, indicating that C2orf64 is involved in an early step of the complex IV assembly process. The results of this study demonstrate that C2orf64 is essential for human complex IV assembly and that C2orf64 mutational analysis should be considered for complex IV deficient patients, in particular those with hypertrophic cardiomyopathy.

A mutation in the Kozak sequence of GATA4 hampers translation in a family with atrial septal defects.

Atrial septal defect (ASD) is the most common congenital heart defect clinically characterized by an opening in the atrial septum. Mutations in GATA4, TBX5, and NKX2-5 underlie this phenotype. Here, we report on the identification of a novel -6 G>C mutation in the highly conserved Kozak sequence in the 5'UTR of GATA4 in a small family presenting with two different forms of ASD. This is the first time a mutation in the Kozak sequence has been linked to heart disease. Functional assays demonstrate reduced GATA4 translation, though the GATA4 transcript levels remain normal. This leads to a reduction of GATA4 protein level, consequently diminishing the ability of GATA4 to transactivate target genes, as demonstrated by using the GATA4-driven Nppa (ANF) promoter. In conclusion, we identified a mutation in the GATA4 Kozak sequence that likely contributes to the pathogenesis of ASD. In general, it points to the importance of accurate protein level regulation during heart development and emphasizes the need to analyze the entire transcribed region when screening for mutations.

Bicuspid aortic valve morphology and associated cardiovascular abnormalities in fetal Turner syndrome: a pathomorphological study.

INTRODUCTION: Bicuspid aortic valve (BAV) is common in Turner syndrome (TS). In adult TS, 82-95% of BAVs have fusion of the right and left coronary leaflets. Data in fetal stages are scarce. The purpose of this study was to gain insight into aortic valve morphology and associated cardiovascular abnormalities in a fetal TS cohort with adverse outcome early in development. MATERIAL AND METHODS: We studied post-mortem heart specimens of 36 TS fetuses and 1 TS newborn. RESULTS: BAV was present in 28 (76%) hearts. BAVs showed fusion of the right and left coronary leaflet (type 1 BAV) in 61%, and fusion of the right coronary and non-coronary leaflet (type 2 BAV) in 39%. There were no significant differences in occurrence of additional cardiovascular abnormalities between type 1 and type 2 BAV. However, all type 2 BAV hearts showed ascending aorta hypoplasia and tubular hypoplasia of the B segment, as opposed to only 55 and 64% of type 1 BAV hearts, respectively. DISCUSSION: The proportion of type 2 BAV seems higher in TS fetuses than in adults. Fetal type 2 BAV hearts all had severe aortic pathology, possibly contributing to a worse prognosis of type 2 than type 1 BAV in TS.

Vascular Ehlers-Danlos Syndrome: A Comprehensive Natural History Study in a Dutch National Cohort of 142 Patients.

BACKGROUND: Vascular Ehlers-Danlos syndrome (vEDS) is a rare connective tissue disorder with a high risk for arterial, bowel, and uterine rupture, caused by heterozygous pathogenic variants in COL3A1. The aim of this cohort study is to provide further insights into the natural history of vEDS and describe genotype-phenotype correlations in a Dutch multicenter cohort to optimize patient care and increase awareness of the disease. METHODS: Individuals with vEDS throughout the Netherlands were included. The phenotype was charted by retrospective analysis of molecular and clinical data, combined with a one-time physical examination. RESULTS: A total of 142 individuals (50% female) participated the study, including 46 index patients (32%). The overall median age at genetic diagnosis was 41.0 years. More than half of the index patients (54.3%) and relatives (53.1%) had a physical appearance highly suggestive of vEDS. In these individuals, major events were not more frequent (P=0.90), but occurred at a younger age (P=0.01). A major event occurred more often and at a younger age in men compared with women (P<0.001 and P=0.004, respectively). Aortic aneurysms (P=0.003) and pneumothoraces (P=0.029) were more frequent in men. Aortic dissection was more frequent in individuals with a COL3A1 variant in the first quarter of the collagen helical domain (P=0.03). CONCLUSIONS: Male sex, type and location of the COL3A1 variant, and physical appearance highly suggestive of vEDS are risk factors for the occurrence and early age of onset of major events. This national multicenter cohort study of Dutch individuals with vEDS provides a valuable basis for improving guidelines for the diagnosing, follow-up, and treatment of individuals with vEDS.

Ebstein anomaly associated with left ventricular noncompaction: an autosomal dominant condition that can be caused by mutations in MYH7.

Left ventricular noncompaction (LVNC) is a relatively common genetic cardiomyopathy, characterized by prominent trabeculations with deep intertrabecular recesses in mainly the left ventricle. Although LVNC often occurs in an isolated entity, it may also be present in various types of congenital heart disease (CHD). The most prevalent CHD in LVNC is Ebstein anomaly, which is a rare form of CHD characterized by apical displacement and partial fusion of the septal and posterior leaflet of the tricuspid valve with the ventricular septum. Several reports of sporadic as well as familial cases of Ebstein anomaly associated with LVNC have been reported. Recent studies identified mutations in the MYH7 gene, encoding the sarcomeric ß-myosin heavy chain protein, in patients harboring this specific phenotype. Here, we will review the association between Ebstein anomaly, LVNC and mutations in MYH7, which seems to represent a subtype of Ebstein anomaly with autosomal dominant inheritance and variable penetrance.

The value of the clinical geneticist caring for adults with congenital heart disease: diagnostic yield and patients' perspective.

For adult patients with congenital heart disease (CHD), knowledge about the origin and inheritance of their CHD is important. Clinical geneticists may play a significant role in their care. We explored the diagnostic yield of clinical genetic consultation of adult CHD patients, patients' motivations for the consultation, implications for reproductive decisions, patients' evaluation of the impact of provided information, and satisfaction with counseling. Chart review was performed on all adult patients referred for CHD to our clinical genetics department between 2000 and 2011 (n = 90). Additionally, a questionnaire was sent to those patients referred between 2005 and 2011 (n = 64), of which 46 useful questionnaires were returned (72% response). Of patients without an etiological diagnosis at referral (n = 83), 17 (20%) were eventually diagnosed with syndromic CHD, 6 (7%) with nonsyndromic monogenetic CHD and 45 (54%) with nonsyndromic multifactorial CHD. The diagnosis remained undetermined in 15 (18%) patients. Half of patients who returned the questionnaire had purposefully postponed having children until after genetic consultation and 13% had changed their mind about having children or not after the consultation. Counseling was valued positively. In this study, we showed the added value of clinical genetic consultation in the care for adult CHD patients: it improves diagnostics by establishing an etiological diagnosis and associated recurrence risk in a substantial proportion of patients and leads to more informed reproductive decisions. With new genetic testing technologies an etiological diagnosis may be established in an increasing number of patients in the near future.

HTAD patient pathway: Strategy for diagnostic work-up of patients and families with (suspected) heritable thoracic aortic diseases (HTAD). A statement from the HTAD working group of VASCERN.

Heritable thoracic aortic diseases (HTAD) are rare pathologies associated with thoracic aortic aneurysms and dissection, which can be syndromic or non-syndromic. They may result from genetic defects. Associated genes identified to date are classified into those encoding components of the (a) extracellular matrix (b) TGFß pathway and (c) smooth muscle contractile mechanism. Timely diagnosis allows for prompt aortic surveillance and prophylactic surgery, hence improving life expectancy and reducing maternal complications as well as providing reassurance to family members when a diagnosis is ruled out. This document is an expert opinion reflecting strategies put forward by medical experts and patient representatives involved in the HTAD Rare Disease Working Group of VASCERN. It aims to provide a patient pathway that improves patient care by diminishing time to diagnosis, facilitating the establishment of a correct diagnosis using molecular genetics when possible, excluding the diagnosis in unaffected persons through appropriate family screening and avoiding overuse of resources. It is being recommended that patients are referred to an expert centre for further evaluation if they meet at least one of the following criteria: (1) thoracic aortic dissection (<70 years if hypertensive; all ages if non-hypertensive), (2) thoracic aortic aneurysm (all adults with Z score >3.5 or 2.5-3.5 if non-hypertensive or hypertensive and <60 years; all children with Z score >3), (3) family history of HTAD with/without a pathogenic variant in a gene linked to HTAD, (4) ectopia lentis without other obvious explanation and (5) a systemic score of >5 in adults and >3 in children. Aortic imaging primarily relies on transthoracic echocardiography with magnetic resonance imaging or computed tomography as needed. Genetic testing should be considered in those with a high suspicion of underlying genetic aortopathy. Though panels vary among centers, for patients with thoracic aortic aneurysm or dissection or systemic features these should include genes with a definitive or strong association to HTAD. Genetic cascade screening and serial aortic imaging should be considered for family screening and follow-up. In conclusion, the implementation of these strategies should help standardise the diagnostic work-up and follow-up of patients with suspected HTAD and the screening of their relatives.

A tailored approach to informing relatives at risk of inherited cardiac conditions: results of a randomised controlled trial.

If undetected, inherited cardiac conditions can lead to sudden cardiac death, while treatment options are available. Predictive DNA testing is therefore advised for at-risk relatives, and probands are currently asked to inform relatives about this. However, fewer than half of relatives attend genetic counselling. In this trial, we compared a tailored approach to informing relatives, in which probands were asked whether they preferred relatives to be informed by themselves or by the genetic counsellor, with current practice. Our primary outcome was uptake of genetic counselling in relatives in the first year after test result disclosure. Secondary outcomes were evaluation of the approach and impact on psychological/family functioning measured 3 (T1) and 9 (T2) months post-disclosure via telephone interviews and questionnaires. We included 96 probands; 482 relatives were eligible for counselling and genetic testing. We observed no significant difference in uptake of genetic counselling between the control (38%) and the intervention (37%) group (p = 0.973). Nor were there significant differences between groups in impact on family/psychological functioning. Significantly more probands in the tailored group were satisfied (p = 0.001) and felt supported (p = 0.003) by the approach, although they also felt somewhat coerced to inform relatives (p < 0.001) and perceived room for improvement (p < 0.001). To conclude, we observed no differences in uptake and impact on family/psychological functioning between the current and tailored approach, but probands in the tailored group more often felt satisfied. Further research on barriers to relatives attending genetic counselling and on how to optimize the provision of a tailored approach is needed.

Adults with congenital heart disease: patients' knowledge and concerns about inheritance.

With recent advances in medical and surgical management, most patients with congenital heart disease (CHD) survive to reproductive age. Current guidelines recommend counseling about inheritance and transmission of CHD to offspring. We evaluated whether adult CHD patients recalled having received information about the inheritance of their CHD, patients' knowledge about inheritance and their concerns in this regard. A questionnaire was sent to 486 non-syndromic CHD patients aged 20-45 years. We received 332 useful questionnaires (response rate 68%). One-third (33%) of patients recalled receiving information about inheritance of CHD from their cardiologist, and 13% had consulted a clinical geneticist. Eight percent of patients who were considering having children estimated the recurrence risk for their own offspring to be 1% or lower, whereas one-fourth (25%) estimated it to be higher than 10%. According to our classification, 44% estimated the recurrence risk in a correct range of magnitude. Additional information about inheritance of CHD was desired by 41% of patients. Forty-two percent of patients considering having children reported concerns about transmitting CHD to offspring. We conclude that a substantial proportion of adult CHD patients lacks knowledge and desires more information about inheritance, indicating a need for better patient education. Current guidelines and/or their implementation do not seem to meet the needs of these patients. A dedicated program of counseling for adults with CHD has to be developed to optimize knowledge and satisfaction with information provision and to reduce or manage concerns regarding inheritance of CHD.

The clinical spectrum of missense mutations of the first aspartic acid of cbEGF-like domains in fibrillin-1 including a recessive family.

Marfan syndrome (MFS) is a dominant disorder with a recognizable phenotype. In most patients with the classical phenotype mutations are found in the fibrillin-1 gene (FBN1) on chromosome 15q21. It is thought that most mutations act in a dominant negative way or through haploinsufficiency. In 9 index cases referred for MFS we detected heterozygous missense mutations in FBN1 predicted to substitute the first aspartic acid of different calcium-binding Epidermal Growth Factor-like (cbEGF) fibrillin-1 domains. A similar mutation was found in homozygous state in 3 cases in a large consanguineous family. Heterozygous carriers of this mutation had no major skeletal, cardiovascular or ophthalmological features of MFS. In the literature 14 other heterozygous missense mutations are described leading to the substitution of the first aspartic acid of a cbEGF domain and resulting in a Marfan phenotype. Our data show that the phenotypic effect of aspartic acid substitutions in the first position of a cbEGF domain can range from asymptomatic to a severe neonatal phenotype. The recessive nature with reduced expression of FBN1 in one of the families suggests a threshold model combined with a mild functional defect of this specific mutation.

Prevalence of congenital heart defects in neuroblastoma patients: a cohort study and systematic review of literature.

Data on the prevalence of congenital heart defects (CHD) in neuroblastoma patients are inconsistent. If CHD are more common in neuroblastoma patients than in the general population, cardiac screening might be warranted. In this study we used echocardiography to determine the prevalence of CHD in a single centre cohort of surviving neuroblastoma patients. In addition, we performed a systematic review of the literature. Echocardiography was performed in 119 of 133 patients (89.5%). Only two patients (1.7%) had CHD. The prevalence of CHD was not significantly different from a previously published control group of 192 leukaemia patients examined by echocardiography (P = 0.49). Literature search revealed 17 studies, showing prevalence rates of CHD in neuroblastoma patients ranging from 0 to 20%. Prevalence was less than 3.6% in the majority of studies. Most studies lacked information on validity. We conclude that current evidence does not support standard cardiac screening in all patients with neuroblastoma.

Preconceptional cystic fibrosis carrier screening: opinions of general practitioners, gynecologists, and pediatricians in the Netherlands.

Knowledge of the opinions of physicians with regard to preconceptional cystic fibrosis (CF) carrier screening and the possible factors that are associated with their opinions is important for the implementation of such a screening program. Data were obtained from a study in which genetic knowledge, opinions with regard to genetic testing and related skills were investigated. A questionnaire, developed and used by American researchers, was adapted to the Dutch health care situation, and sent to randomly selected general practitioners (GPs) (n = 200), gynecologists (GYNs) (n = 300), and pediatricians (PEDs) (n = 265). In this part of the study, their opinions with regard to genetic preconceptional CF carrier screening in different situations were assessed. The response rate for the GPs, GYNs, and PEDs was 64%, 69%, and 72%, respectively. In total, 63% of the GPs, 69% of the GYNs and 72% of the PEDs supported preconceptional CF carrier testing if a couple requested a test. Sixteen percent, 19% and 25%, respectively, were in favor of actively offering a test with 95% test sensitivity to all couples who were planning a pregnancy. A positive opinion on preconceptional CF carrier screening was associated with the following variables: "considering the test sensitivity as less important" (GPs, GYNs), "high perceived risk of having a child with CF" (GYNs), "providing genetic counselling in their own practice" (PEDs) and "reassurance when both partners test negative" (PEDs). Physicians are sympathetic toward preconceptional CF carrier screening if the couples themselves request a test. Physicians had reservations about routinely offering a CF carrier test.

Comparison of activities and attitudes of general practitioners concerning genetic counseling over a 10-year time-span.

The aim of this study was to investigate whether the activities and attitudes of general practitioners (GPs) concerning genetic counseling have changed between 1989 and 1999. In 1989 a random sample of 124 GPs in The Netherlands was selected. Of these GPs, 98 were contacted again in 1999 and 71 completed the questionnaire. The study showed an increase in the percentage of GPs who provided genetic counseling when a risk factor for having a child with a congenital disorder was present and known. In both 1989 and 1999, the GPs seldom used a recommended combination of oral and written information, and only data that was available in the databases on the risk indicator 'use of medication' increased over the years. GPs are still supporters of a directive method of counseling, and seem to believe that the main goal of genetic counseling is to prevent hereditary and congenital disorders. Although, between 1989 and 1999 more GPs provided genetic counseling when a risk indicator was present and known or referred to a clinical geneticist, only limited improvement was found in the activities of GPs to attempt to collect these data.

HCN4 mutations in multiple families with bradycardia and left ventricular noncompaction cardiomyopathy.

BACKGROUND: Familial forms of primary sinus bradycardia have sometimes been attributed to mutations in HCN4, SCN5A, and ANK2. In these studies, no structural cardiac alterations were reported in mutation carriers. However, a cluster of reports in the literature describe patients presenting with sinus bradycardia in association with left ventricular noncompaction cardiomyopathy (LVNC), pointing to a shared genetic cause. OBJECTIVES: This study sought to identify the genetic defect underlying the combined clinical presentation of bradycardia and LVNC, hypothesizing that these 2 clinical abnormalities have a common genetic cause. METHODS: Exome sequencing was carried out in 2 cousins from the index family that were affected by the combined bradycardia-LVNC phenotype; shared variants thus identified were subsequently overlaid with the chromosomal regions shared among 5 affected family members that were identified using single nucleotide polymorphism array analysis. RESULTS: The combined linkage analysis and exome sequencing in the index family identified 11 novel variants shared among the 2 affected cousins. One of these, p.Gly482Arg in HCN4, segregated with the combined bradycardia and LVNC phenotype in the entire family. Subsequent screening of HCN4 in 3 additional families with the same clinical combination of bradycardia and LVNC identified HCN4 mutations in each. In electrophysiological studies, all found HCN4 mutations showed a more negative voltage dependence of activation, consistent with the observed bradycardia. CONCLUSIONS: Although mutations in HCN4 have been previously linked to bradycardia, our study provides the first evidence to our knowledge that mutations in this ion channel gene also may be associated with structural abnormalities of the myocardium.

The ambiguous role of NKX2-5 mutations in thyroid dysgenesis.

NKX2-5 is a homeodomain-containing transcription factor implied in both heart and thyroid development. Numerous mutations in NKX2-5 have been reported in individuals with congenital heart disease (CHD), but recently a select few have been associated with thyroid dysgenesis, among which the p.A119S variation. We sequenced NKX2-5 in 303 sporadic CHD patients and 38 families with at least two individuals with CHD. The p.A119S variation was identified in two unrelated patients: one was found in the proband of a family with four affected individuals with CHD and the other in a sporadic CHD patient. Clinical evaluation of heart and thyroid showed that the mutation did not segregate with CHD in the familial case, nor did any of the seven mutation carriers have thyroid abnormalities. We tested the functional consequences of the p.A119S variation in a cellular context by performing transactivation assays with promoters relevant for both heart and thyroid development in rat heart derived H10 cells and HELA cells. There was no difference between wildtype NKX2-5 and p.A119S NKX2-5 in activation of the investigated promoters in both cell lines. Additionally, we reviewed the current literature on the topic, showing that there is no clear evidence for a major pathogenic role of NKX2-5 mutations in thyroid dysgenesis. In conclusion, our study demonstrates that p.A119S does not cause CHD or TD and that it is a rare variation that behaves equal to wildtype NKX2-5. Furthermore, given the wealth of published evidence, we suggest that NKX2-5 mutations do not play a major pathogenic role in thyroid dysgenesis, and that genetic testing of NKX2-5 in TD is not warranted.