Mortality of Inherited Arrhythmia Syndromes Insight Into Their Natural History

Background-For most arrhythmia syndromes, the risk of sudden cardiac death for asymptomatic mutation carriers is ill defined. Data on the natural history of these diseases, therefore, are essential. The family tree mortality ratio method offers the unique possibility to study the natural history at a time when the disease was not known and patients received no treatment. Methods and Results-In 6 inherited arrhythmia syndromes caused by specific mutations, we analyzed all-cause mortality with the family tree mortality ratio method (main outcome measure, standardized mortality ratio [SMR]). In long-QT syndrome (LQTS) type 1, severely increased mortality risk during all years of childhood was observed (1-19 years), in particular during the first 10 years of life (SMR, 2.9; 95% CI, 1.5-5.1). In LQTS type 2, we observed increasing SMRs starting from age 15 years, which just reached significance between age 30 and 39 (SMR, 4.0; 95% CI, 1.1-10.0). In LQTS type 3, the SMR was increased between age 15 and 19 years (SMR, 5.8; 95% CI, 1.2-16.9). In the SCN5A overlap syndrome, excess mortality was observed between age 10 and 59 years, with a peak between 20 and 39 years (SMR, 3.8; 95% CI, 2.5-5.7). In catecholaminergic polymorphic ventricular tachycardia, excess mortality was restricted to ages 20 to 39 years (SMR, 3.0; 95% CI, 1.3-6.0). In Brugada syndrome, excess mortality was observed between age 40 and 59 (SMR, 1.79; 95% CI, 1.2-2.4), particularly in men. Conclusions-We identified age ranges during which the mortality risk manifests in an unselected and untreated population, which can guide screening in these families. (Circ Cardiovasc Genet. 2012;5:183-189.

Low rate of cardiac events in first-degree relatives of diagnosis-negative young sudden unexplained death syndrome victims during follow-up

BACKGROUND: Sudden unexplained death syndrome (SUDS) in young individuals often results from inherited cardiac disease. Accordingly, comprehensive examination in surviving first-degree relatives unmasks such disease in approximately 35% of the families. It is unknown whether individuals from diagnosis-negative families are at risk of developing manifest disease or cardiac events during follow-up.OBJECTIVE: This study aimed to study the prognosis of first-degree relatives of young SUDS victims, in whom the initial cardiologic and genetic examination did not lead to a diagnosis.METHODS: We retrieved vital status of surviving first-degree relatives from 83 diagnosis-negative families who presented to our cardiogenetics department between 1996 and 2009 because of SUDS in ≥1 relatives aged 1-50 years. Moreover, we contacted relatives who previously visited our center for detailed information.RESULTS: We obtained detailed information (median follow-up 6.6 years; interquartile range 4.7-9.6 years) in 340 of 417 first-degree relatives (81.5%) from 77 of 83 families (92.8%). Vital status, available in 405 relatives (97.1%), showed that 20 relatives (4.9%) died during follow-up, including 1 natural death before the age of 50. This girl belonged to a family with multiple cases of idiopathic ventricular fibrillation and SUDS, including another successfully resuscitated sibling during follow-up. Two hundred thirty-four of 340 first-degree relatives (68.8%) underwent cardiologic examination. Of these, 76 (32.5%) were reevaluated. Inherited cardiac disease was diagnosed in 3 families (3.6%).CONCLUSION: In first-degree relatives of young SUDS victims with no manifest abnormalities during the initial examination, the risk of developing manifest inherited cardiac disease or cardiac events during follow-up is low. This does not apply to families with obvious familial SUDS.</p

Correction: Clinical epigenomics: genome-wide DNA methylation analysis for the diagnosis of Mendelian disorders (Genetics in Medicine, (2021), 23, 6, (1065-1074), 10.1038/s41436-020-01096-4)

A Correction to this paper has been published: https://doi.org/10.1038/s41436-021-01130-z

Clinical epigenomics: genome-wide DNA methylation analysis for the diagnosis of Mendelian disorders

Purpose: We describe the clinical implementation of genome-wide DNA methylation analysis in rare disorders across the EpiSign diagnostic laboratory network and the assessment of results and clinical impact in the first subjects tested. Methods: We outline the logistics and data flow between an integrated network of clinical diagnostics laboratories in Europe, the United States, and Canada. We describe the clinical validation of EpiSign using 211 specimens and assess the test performance and diagnostic yield in the first 207 subjects tested involving two patient subgroups: the targeted cohort (subjects with previous ambiguous/inconclusive genetic findings including genetic variants of unknown clinical significance) and the screening cohort (subjects with clinical findings consistent with hereditary neurodevelopmental syndromes and no previous conclusive genetic findings). Results: Among the 207 subjects tested, 57 (27.6%) were positive for a diagnostic episignature including 48/136 (35.3%) in the targeted cohort and 8/71 (11.3%) in the screening cohort, with 4/207 (1.9%) remaining inconclusive after EpiSign analysis. Conclusion: This study describes the implementation of diagnostic clinical genomic DNA methylation testing in patients with rare disorders. It provides strong evidence of clinical utility of EpiSign analysis, including the ability to provide conclusive findings in the majority of subjects tested

Delineating the molecular and phenotypic spectrum of the SETD1B-related syndrome

Purpose: Pathogenic variants in SETD1B have been associated with a syndromic neurodevelopmental disorder including intellectual disability, language delay, and seizures. To date, clinical features have been described for 11 patients with (likely) pathogenic SETD1B sequence variants. This study aims to further delineate the spectrum of the SETD1B-related syndrome based on characterizing an expanded patient cohort. Methods: We perform an in-depth clinical characterization of a cohort of 36 unpublished individuals with SETD1B sequence variants, describing their molecular and phenotypic spectrum. Selected variants were functionally tested using in vitro and genome-wide methylation assays. Results: Our data present evidence for a loss-of-function mechanism of SETD1B variants, resulting in a core clinical phenotype of global developmental delay, language delay including regression, intellectual disability, autism and other behavioral issues, and variable epilepsy phenotypes. Developmental delay appeared to precede seizure onset, suggesting SETD1B dysfunction impacts physiological neurodevelopment even in the absence of epileptic activity. Males are significantly overrepresented and more severely affected, and we speculate that sex-linked traits could affect susceptibility to penetrance and the clinical spectrum of SETD1B variants. Conclusion: Insights from this extensive cohort will facilitate the counseling regarding the molecular and phenotypic landscape of newly diagnosed patients with the SETD1B-related syndrome

Peri-operative red blood cell transfusion in neonates and infants: NEonate and Children audiT of Anaesthesia pRactice IN Europe: A prospective European multicentre observational study

BACKGROUND: Little is known about current clinical practice concerning peri-operative red blood cell transfusion in neonates and small infants. Guidelines suggest transfusions based on haemoglobin thresholds ranging from 8.5 to 12 g dl-1, distinguishing between children from birth to day 7 (week 1), from day 8 to day 14 (week 2) or from day 15 (≥week 3) onwards. OBJECTIVE: To observe peri-operative red blood cell transfusion practice according to guidelines in relation to patient outcome. DESIGN: A multicentre observational study. SETTING: The NEonate-Children sTudy of Anaesthesia pRactice IN Europe (NECTARINE) trial recruited patients up to 60 weeks' postmenstrual age undergoing anaesthesia for surgical or diagnostic procedures from 165 centres in 31 European countries between March 2016 and January 2017. PATIENTS: The data included 5609 patients undergoing 6542 procedures. Inclusion criteria was a peri-operative red blood cell transfusion. MAIN OUTCOME MEASURES: The primary endpoint was the haemoglobin level triggering a transfusion for neonates in week 1, week 2 and week 3. Secondary endpoints were transfusion volumes, 'delta haemoglobin' (preprocedure - transfusion-triggering) and 30-day and 90-day morbidity and mortality. RESULTS: Peri-operative red blood cell transfusions were recorded during 447 procedures (6.9%). The median haemoglobin levels triggering a transfusion were 9.6 [IQR 8.7 to 10.9] g dl-1 for neonates in week 1, 9.6 [7.7 to 10.4] g dl-1 in week 2 and 8.0 [7.3 to 9.0] g dl-1 in week 3. The median transfusion volume was 17.1 [11.1 to 26.4] ml kg-1 with a median delta haemoglobin of 1.8 [0.0 to 3.6] g dl-1. Thirty-day morbidity was 47.8% with an overall mortality of 11.3%. CONCLUSIONS: Results indicate lower transfusion-triggering haemoglobin thresholds in clinical practice than suggested by current guidelines. The high morbidity and mortality of this NECTARINE sub-cohort calls for investigative action and evidence-based guidelines addressing peri-operative red blood cell transfusions strategies. TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT02350348

Sodium channelopathies: do we really understand what's going on?

Long-QT syndrome, Brugada syndrome, and conduction disease may be caused by mutations in the cardiac sodium channel gene SCN5A, and from the ECG one can already presume either a gain- or a loss-of-function defect. We describe a family harboring 2 SCN5A mutations: the ΔKPQ mutation, the "classical" gain-of-function mutation associated with Long-QT syndrome, and the I1660V mutation, a loss-of-function mutation associated with Brugada syndrome. However, we were surprised by the result of genetic testing in this family. One son who carried the ΔKPQ mutation but not the I1660V mutation did not show the expected Long-QT phenotype but, unexpectedly, showed a conduction disease/Brugada phenotyp

A de novo mutation in KCNN3 associated with autosomal dominant idiopathic non-cirrhotic portal hypertension

Non-cirrhotic portal hypertension is characterized by histopathological abnormalities in the liver, mostly affecting small intrahepatic portal veins that cause portal hypertension in the absence of cirrhosis. It can be secondary to coagulation disorders or toxic agents. However, most cases are idiopathic non-cirrhotic portal hypertension (INCPH) and familial cases are rare. We report a family in which a father and three of his four children conceived with three different mothers are affected by INCPH. Whole exome and Sanger sequencing showed the father to have a de novo single nucleotide substitution c.1348G>C in the KCNN3 gene that was transmitted to all three of his affected offspring. The KCNN3 gene encodes small conductance calcium-activated potassium (SK) channel 3. SK channels are involved in the regulation of arterial and venous vascular tone by causing smooth muscle relaxation on activation. No data exist on the expression and function of SK channels in portal veins. The autosomal dominant inheritance in this unique pedigree and the single de novo mutation identified, strongly suggests that KCNN3 mutations have a pathogenetic role in INCP

Congenital aplastic anemia caused by mutations in the SBDS gene: A rare presentation of Shwachman-Diamond syndrome

Clinical Findings. Aplastic anemia was diagnosed at birth for a first child from healthy nonconsanguineous parents. The girl had hypoglycemia, which normalized within 2 months. Cow milk allergy was suspected initially, because of skin lesions and diarrhea, followed by severe growth retardation. Clinical and radiologic symptoms gradually became typical for Shwachman-Diamond syndrome. Two common mutations in the SBDS gene (183-184TA --> CT [K62X] and IVS2(258) + 2T --> C [C84fs]) were found. Results. Bone marrow transplantation from a matched unrelated donor was unsuccessful. The genetic information from the deceased patient enabled us to perform prenatal molecular studies during the subsequent pregnancy, successfully predicting a nonaffected child. Conclusions. This report describes for the first time the hematologic abnormalities of congenital aplastic anemia and prolonged neonatal hypoglycemia as the presenting symptoms of Shwachman-Diamond syndrome. The finding of common mutations in the presence of these symptoms at birth suggests the lack of a clear phenotype-genotype relationship in this syndrom

Active Cascade Screening in Primary Inherited Arrhythmia Syndromes:Does It Lead to Prophylactic Treatment?

Objectives: The purpose of this study was to investigate the follow-up and treatment of the mutation-carrying relatives of a proband with an inherited arrhythmia syndrome. Background: The congenital long QT syndrome (LQTS), catecholaminergic polymorphic ventricular tachycardia (CPVT), and Brugada syndrome (BrS) are primary inherited arrhythmia syndromes that may cause syncope and sudden cardiac death in young individuals. After establishing the disease-causing deoxyribonucleic acid (DNA) mutation in probands, we actively conducted cascade screening to identify, most often asymptomatic, relatives who are also at risk of life-threatening arrhythmias. Methods: We retrospectively collected data from our cardiogenetics database and patient records and analyzed whether the identified carriers received prophylactic treatment. Results: From 1996 to 2008, 130 probands with a disease-causing mutation in one of the involved genes were identified, and 509 relatives tested positive for the disease-causing familial mutation. These subjects subsequently underwent cardiologic investigation (electrocardiography, exercise testing, Holter monitoring, ajmaline testing, echocardiography, where appropriate). After a mean follow-up of 69 ± 31 months (LQTS), 60 ± 19 months (CPVT), and 56 ± 21 months (BrS), treatment was initiated and ongoing in 65% (199 of 308), 71% (85 of 120), and 6% (5 of 81) of the relatives in the LQTS, CPVT, and BrS families, respectively. Eight carriers were lost to follow-up. Treatment included drug treatment (n = 249) or implantation of pacemakers (n = 26) or cardioverter-defibrillators (n = 14). All mutation carriers received lifestyle instructions and a list of drugs to be avoided. Conclusions: Cascade screening in families with LQTS, BrS, or CPVT, which was based on DNA mutation carrying and subsequent cardiologic investigation, resulted in immediate prophylactic treatment in a substantial proportion of carriers, although these proportions varied significantly between the different diseases. © 2010 American College of Cardiology Foundation