Parental Attitudes and Ideas Regarding Newborn Screening for Familial Hypercholesterolemia.

BACKGROUND: Familial hypercholesterolemia (FH) is an inherited disease which causes premature atherosclerotic cardiovascular disease. However, less than 10% of individuals with FH have been identified. OBJECTIVE: To assess parental perspectives for inclusion of FH on routine newborn screening (NBS) and to highlight potential benefits, harms, and ethical concerns. METHODS: Telephone interviews of two groups were conducted: 1) parents of children diagnosed with FH, and 2) parents of children diagnosed with a genetic condition through NBS. Stratified purposive sampling was used to ensure adequate representation. The 11 telephone interviews were conducted in 30-min sessions guided by a semi-structured interview script. At the beginning of the interview, participants were educated on the NBS process and FH. The interviews were transcribed verbatim, and a thematic analysis was performed in multiple steps. RESULTS: All interviewees indicated that they would be interested in having their child be screened for FH on the newborn screen. Reasons supporting screening during the newborn period included knowing their child's diagnosis, the ability to screen family members for FH, incorporation of lifestyle changes, and access to preventive care. Negatives surrounding screening during the newborn period included increased stress or anxiety, knowledge, stigma, and the delay from diagnosis to initiation of pharmacotherapy for FH. CONCLUSION: While these interviewees were in favor of NBS for FH, further education of parents and clinicians is needed to ensure proper implementation. The results of this study may be useful to formulate family notification and care protocols for newborns diagnosed with FH and other diseases.

What is already known on this subject? Familial hypercholesterolemia is a common inherited disorder that predisposes to early cardiovascular disease, but most affected individuals are not diagnosed. Childhood cholesterol screening is an effective but underutilized diagnostic tool. Previous studies report parents find childhood cholesterol screening acceptable, but it is not known if screening newborns would also be acceptable.What does this study add? Interviewees found screening newborns for familial hypercholesterolemia acceptable and would agree to screen their own newborn. The ability to screen other family members and access to early treatment were important factors in their decision to screen. Education of clinicians about familial hypercholesterolemia was an important concern raised by interviewees.

An International Multicenter Evaluation of Inheritance Patterns, Arrhythmic Risks, and Underlying Mechanisms of CASQ2-Catecholaminergic Polymorphic Ventricular Tachycardia.

BACKGROUND: Genetic variants in calsequestrin-2 (CASQ2) cause an autosomal recessive form of catecholaminergic polymorphic ventricular tachycardia (CPVT), although isolated reports have identified arrhythmic phenotypes among heterozygotes. Improved insight into the inheritance patterns, arrhythmic risks, and molecular mechanisms of CASQ2-CPVT was sought through an international multicenter collaboration. METHODS: Genotype-phenotype segregation in CASQ2-CPVT families was assessed, and the impact of genotype on arrhythmic risk was evaluated using Cox regression models. Putative dominant CASQ2 missense variants and the established recessive CASQ2-p.R33Q variant were evaluated using oligomerization assays and their locations mapped to a recent CASQ2 filament structure. RESULTS: A total of 112 individuals, including 36 CPVT probands (24 homozygotes/compound heterozygotes and 12 heterozygotes) and 76 family members possessing at least 1 presumed pathogenic CASQ2 variant, were identified. Among CASQ2 homozygotes and compound heterozygotes, clinical penetrance was 97.1% and 26 of 34 (76.5%) individuals had experienced a potentially fatal arrhythmic event with a median age of onset of 7 years (95% CI, 6-11). Fifty-one of 66 CASQ2 heterozygous family members had undergone clinical evaluation, and 17 of 51 (33.3%) met diagnostic criteria for CPVT. Relative to CASQ2 heterozygotes, CASQ2 homozygote/compound heterozygote genotype status in probands was associated with a 3.2-fold (95% CI, 1.3-8.0; P=0.013) increased hazard of a composite of cardiac syncope, aborted cardiac arrest, and sudden cardiac death, but a 38.8-fold (95% CI, 5.6-269.1; P<0.001) increased hazard in genotype-positive family members. In vitro turbidity assays revealed that p.R33Q and all 6 candidate dominant CASQ2 missense variants evaluated exhibited filamentation defects, but only p.R33Q convincingly failed to dimerize. Structural analysis revealed that 3 of these 6 putative dominant negative missense variants localized to an electronegative pocket considered critical for back-to-back binding of dimers. CONCLUSIONS: This international multicenter study of CASQ2-CPVT redefines its heritability and confirms that pathogenic heterozygous CASQ2 variants may manifest with a CPVT phenotype, indicating a need to clinically screen these individuals. A dominant mode of inheritance appears intrinsic to certain missense variants because of their location and function within the CASQ2 filament structure.

Adaptation and validation of the ACMG/AMP variant classification framework for MYH7-associated inherited cardiomyopathies: recommendations by ClinGen's Inherited Cardiomyopathy Expert Panel.

PurposeIntegrating genomic sequencing in clinical care requires standardization of variant interpretation practices. The Clinical Genome Resource has established expert panels to adapt the American College of Medical Genetics and Genomics/Association for Molecular Pathology classification framework for specific genes and diseases. The Cardiomyopathy Expert Panel selected MYH7, a key contributor to inherited cardiomyopathies, as a pilot gene to develop a broadly applicable approach.MethodsExpert revisions were tested with 60 variants using a structured double review by pairs of clinical and diagnostic laboratory experts. Final consensus rules were established via iterative discussions.ResultsAdjustments represented disease-/gene-informed specifications (12) or strength adjustments of existing rules (5). Nine rules were deemed not applicable. Key specifications included quantitative frameworks for minor allele frequency thresholds, the use of segregation data, and a semiquantitative approach to counting multiple independent variant occurrences where fully controlled case-control studies are lacking. Initial inter-expert classification concordance was 93%. Internal data from participating diagnostic laboratories changed the classification of 20% of the variants (n = 12), highlighting the critical importance of data sharing.ConclusionThese adapted rules provide increased specificity for use in MYH7-associated disorders in combination with expert review and clinical judgment and serve as a stepping stone for genes and disorders with similar genetic and clinical characteristics.

Clinical Cardiovascular Genetic Counselors Take a Leading Role in Team-based Variant Classification.

We sought to delineate the genetic test review and interpretation practices of clinical cardiovascular genetic counselors. A one-time anonymous online survey was taken by 46 clinical cardiovascular genetic counselors recruited through the National Society of Genetic Counselors Cardiovascular Special Interest Group. Nearly all (95.7%) gather additional information on variants reported on clinical genetic test reports and most (81.4%) assess the classification of such variants. Clinical cardiovascular genetic counselors typically (81.0%) classify variants in collaboration with cardiologist and/or geneticist colleagues, with the genetic counselor as the team member who is primarily responsible. Variant classification is a relatively recent (mean 3.2 years) addition to practice. Most genetic counselors learned classification skills on the job from clinical and laboratory colleagues. Recent graduates were more likely to have learned this in graduate school (p < 0.001). Genetic counselors are motivated to take responsibility for the classification of variants because of prior experiences with variant reclassification, inconsistencies between laboratories, and incomplete laboratory reports. They are also driven by a sense of professional duty and their proximity to the clinical context. This practice represents a broadening of the skill set of clinical cardiovascular genetic counselors and a unique expertise that they contribute to the interdisciplinary teams in which they work.

Meta-Analysis of Genome-Wide Association Studies Reveals Genetic Mechanisms of Supraventricular Arrhythmias.

BACKGROUND: Substantial data support a heritable basis for supraventricular tachycardias, but the genetic determinants and molecular mechanisms of these arrhythmias are poorly understood. We sought to identify genetic loci associated with atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular accessory pathways or atrioventricular reciprocating tachycardia (AVAPs/AVRT). METHODS: We performed multiancestry meta-analyses of genome-wide association studies to identify genetic loci for AVNRT (4 studies) and AVAP/AVRT (7 studies). We assessed evidence supporting the potential causal effects of candidate genes by analyzing relations between associated variants and cardiac gene expression, performing transcriptome-wide analyses, and examining prior genome-wide association studies. RESULTS: Analyses comprised 2384 AVNRT cases and 106 489 referents, and 2811 AVAP/AVRT cases and 1,483 093 referents. We identified 2 significant loci for AVNRT, which implicate NKX2-5 and TTN as disease susceptibility genes. A transcriptome-wide association analysis supported an association between reduced predicted cardiac expression of NKX2-5 and AVNRT. We identified 3 significant loci for AVAP/AVRT, which implicate SCN5A, SCN10A, and TTN/CCDC141. Variant associations at several loci have been previously reported for cardiac phenotypes, including atrial fibrillation, stroke, Brugada syndrome, and electrocardiographic intervals. CONCLUSIONS: Our findings highlight gene regions associated with ion channel function (AVAP/AVRT), as well as cardiac development and the sarcomere (AVAP/AVRT and AVNRT) as important potential effectors of supraventricular tachycardia susceptibility.

Digenic inheritance novel mutations in SCN5a and SNTA1 increase late I(Na) contributing to LQT syndrome.

SCN5A and SNTA1 are reported susceptible genes for long QT syndrome (LQTS). This study was designed to elucidate a plausible pathogenic arrhythmia mechanism for the combined novel mutations R800L-SCN5A and A261V-SNTA1 on cardiac sodium channels. A Caucasian family with syncope and marginally prolonged QT interval was screened for LQTS-susceptibility genes and found to harbor the R800L mutation in SCN5A and A261V mutation in SNTA1, and those with both mutations had the strongest clinical phenotype. The mutations were engineered into the most common splice variant of human SCN5A and SNTA1 cDNA, respectively, and sodium current (INa) was characterized in human embryonic kidney 293 cells cotransfected with neuronal nitric oxide synthase (nNOS) and the cardiac isoform of the plasma membrane Ca-ATPase (PMCA4b). Peak INa densities were unchanged for wild-type (WT) and for mutant channels containing R800L-SCN5A, A261V-SNTA1, or R800L-SCN5A plus A261V-SNTA1. However, late INa for either single mutant was moderately increased two- to threefold compared with WT. The combined mutations of R800L-SCN5A plus A261V-SNTA1 significantly enhanced the INa late/peak ratio by 5.6-fold compared with WT. The time constants of current decay of combined mutant channel were markedly increased. The gain-of-function effect could be blocked by the N(G)-monomethyl-l-arginine, a nNOS inhibitor. We conclude that novel mutations in SCN5A and SNTA1 jointly exert a nNOS-dependent gain-of-function on SCN5A channels, which may consequently prolong the action potential duration and lead to LQTS phenotype.

Elucidation of ALG10B as a Novel Long-QT Syndrome-Susceptibility Gene.

BACKGROUND: Long-QT syndrome (LQTS) is characterized by QT prolongation and increased risk for syncope, seizures, and sudden cardiac death. The majority of LQTS stems from pathogenic mutations in KCNQ1, KCNH2, or SCN5A. However, ≈10% of patients with LQTS remain genetically elusive. We utilized genome sequencing to identify a novel LQTS genetic substrate in a multigenerational genotype-negative LQTS pedigree. METHODS: Genome sequencing was performed on 5 affected family members. Only rare nonsynonymous variants present in all affected family members were considered. The candidate variant was characterized functionally in patient-derived induced pluripotent stem cell and gene-edited, variant corrected, isogenic control induced pluripotent stem cell-derived cardiomyocytes. RESULTS: A missense variant (p.G6S) was identified in ALG10B-encoded α-1,2-glucosyltransferase B protein. ALG10B (alpha-1,2-glucosyltransferase B protein) is a known interacting protein of KCNH2-encoded Kv11.1 (HERG [human Ether-à-go-go-related gene]). Compared with isogenic control, ALG10B-p.G6S induced pluripotent stem cell-derived cardiomyocytes showed (1) decreased protein expression of ALG10B (p.G6S, 0.7±0.18, n=8 versus control, 1.25±0.16, n=9; P<0.05), (2) significant retention of HERG in the endoplasmic reticulum (P<0.0005), and (3) a significantly prolonged action potential duration confirmed by both patch clamp (p.G6S, 531.1±38.3 ms, n=15 versus control, 324.1±21.8 ms, n=13; P<0.001) and multielectrode assay (P<0.0001). Lumacaftor-a compound known to rescue HERG trafficking-shortened the pathologically prolonged action potential duration of ALG10B-p.G6S induced pluripotent stem cell-derived cardiomyocytes by 10.6% (n=31 electrodes; P<0.001). CONCLUSIONS: Here, we demonstrate that ALG10B-p.G6S downregulates ALG10B, resulting in defective HERG trafficking and action potential duration prolongation. Therefore, ALG10B is a novel LQTS-susceptibility gene underlying the LQTS phenotype observed in a multigenerational pedigree. ALG10B mutation analysis may be warranted, especially in genotype-negative patients with an LQT2-like phenotype.

Clinical and Functional Characterization of Ryanodine Receptor 2 Variants Implicated in Calcium-Release Deficiency Syndrome.

Importance: Calcium-release deficiency syndrome (CRDS), which is caused by loss-of-function variants in cardiac ryanodine receptor 2 (RyR2), is an emerging cause of ventricular fibrillation. However, the lack of complex polymorphic/bidirectional ventricular tachyarrhythmias during exercise stress testing (EST) may distinguish it from catecholaminergic polymorphic ventricular tachycardia (CPVT). Recently, in the first clinical series describing the condition, mouse and human studies showed that the long-burst, long-pause, short-coupled ventricular extra stimulus (LBLPS) electrophysiology protocol reliably induced CRDS ventricular arrhythmias. Data from larger populations with CRDS and its associated spectrum of disease are lacking. Objective: To further insight into CRDS through international collaboration. Design, Setting, and Participants: In this multicenter observational cohort study, probands with unexplained life-threatening arrhythmic events and an ultrarare RyR2 variant were identified. Variants were expressed in HEK293 cells and subjected to caffeine stimulation to determine their functional impact. Data were collected from September 1, 2012, to March 6, 2021, and analyzed from August 9, 2015, to March 6, 2021. Main Outcomes and Measures: The functional association of RyR2 variants found in putative cases of CRDS and the associated clinical phenotype(s). Results: Of 10 RyR2 variants found in 10 probands, 6 were loss-of-function, consistent with CRDS (p.E4451del, p.F4499C, p.V4606E, p.R4608Q, p.R4608W, and p.Q2275H) (in 4 [67%] male and 2 [33%] female probands; median age at presentation, 22 [IQR, 8-34] years). In 5 probands with a documented trigger, 3 were catecholamine driven. During EST, 3 probands with CRDS had no arrhythmias, 1 had a monomorphic couplet, and 2 could not undergo EST (deceased). Relatives of the decedents carrying the RyR2 variant did not have EST results consistent with CPVT. After screening 3 families, 13 relatives were diagnosed with CRDS, including 3 with previous arrhythmic events (23%). None had complex ventricular tachyarrhythmias during EST. Among the 19 confirmed cases with CRDS, 10 had at least 1 life-threatening event at presentation and/or during a median follow-up of 7 (IQR, 6-18) years. Two of the 3 device-detected ventricular fibrillation episodes were induced by a spontaneous LBLPS-like sequence. ß-Blockers were used in 16 of 17 surviving patients (94%). Three of 16 individuals who were reportedly adherent to ß-blocker therapy (19%) had breakthrough events. Conclusions and Relevance: The results of this study suggest that calcium-release deficiency syndrome due to RyR2 loss-of-function variants mechanistically and phenotypically differs from CPVT. Ventricular fibrillation may be precipitated by a spontaneous LBLPS-like sequence of ectopy; however, CRDS remains difficult to recognize clinically. These data highlight the need for better diagnostic tools and treatments for this emerging condition.

Psychosocial consequences of false-positive newborn screens for cystic fibrosis.

This study was designed to develop a framework for understanding parents' perspectives about the psychosocial consequences of false-positive newborn screening (NBS) results for cystic fibrosis (CF). Through content analysis of interviews with 87 parents of 44 infants, we found that receipt of genetic information through NBS affected parents on intrapersonal and interpersonal levels within a relational family system. Repercussions included wondering about test accuracy, the child's health, and the future; gaining new perspectives and strengthening relationships; questioning paternity; wondering if other relatives had CF/were carriers; searching for the genetic source; sharing genetic information; supporting NBS; and feeling empathy for parents of affected children. We concluded that abnormal NBS results that involve genetic testing can have psychosocial consequences that affect entire families. These findings merit additional investigation of long-term psychosocial sequelae for false-positive results, interventions to reduce adverse iatrogenic outcomes, and the relevance of the relational family system framework to other genetic testing.

Long QT Syndrome KCNH2 Variant Induces hERG1a/1b Subunit Imbalance in Patient-Specific Induced Pluripotent Stem Cell-Derived Cardiomyocytes.

[Figure: see text].

Shared Decision Making in Cardiac Electrophysiology Procedures and Arrhythmia Management.

Shared decision making (SDM) has been advocated to improve patient care, patient decision acceptance, patient-provider communication, patient motivation, adherence, and patient reported outcomes. Documentation of SDM is endorsed in several society guidelines and is a condition of reimbursement for selected cardiovascular and cardiac arrhythmia procedures. However, many clinicians argue that SDM already occurs with clinical encounter discussions or the process of obtaining informed consent and note the additional imposed workload of using and documenting decision aids without validated tools or evidence that they improve clinical outcomes. In reality, SDM is a process and can be done without decision tools, although the process may be variable. Also, SDM advocates counter that the low-risk process of SDM need not be held to the high bar of demonstrating clinical benefit and that increasing the quality of decision making should be sufficient. Our review leverages a multidisciplinary group of experts in cardiology, cardiac electrophysiology, epidemiology, and SDM, as well as a patient advocate. Our goal is to examine and assess SDM methodology, tools, and available evidence on outcomes in patients with heart rhythm disorders to help determine the value of SDM, assess its possible impact on electrophysiological procedures and cardiac arrhythmia management, better inform regulatory requirements, and identify gaps in knowledge and future needs.

Newborn screening: an appeal for improved parent education.

OBJECTIVE: The purpose of this study, which was part of a larger investigation of newborn screening (NBS) for cystic fibrosis (CF), was to learn how parents were informed about NBS and obtain their suggestions for improving the process of educating parents about NBS. METHOD: Qualitative study using directed and summative content analyses was conducted on 100 interviews with 193 parents of 100 newborns recruited from 4 clinical populations including parents of infants with (1) a CF diagnosis, (2) one CF mutation and therefore CF carriers, (3) congenital hypothyroidism, and (4) normal screening results. RESULTS: Parents described much inconsistency in the timing of and methods used to inform them about NBS. Mothers with higher income were 3.69 times more likely to receive information before their infants' births than mothers with lower income. Parents recommended improving verbal and written communication with parents about NBS at multiple junctures from preconception to the infant's first few days of life. Parents suggested that providers take time to explain the purpose and importance of NBS, which diseases are included in testing, and when parents can expect results. CONCLUSION: These findings suggest a need to establish evidence-based guidelines for informing parents about NBS.

A Case for Inclusion of Genetic Counselors in Cardiac Care.

Recent advances in genetic testing for heritable cardiac diseases have led to an increasing involvement of the genetic counselor in cardiology practice. We present a series of cases collected from a nationwide query of genetics professionals regarding issues related to cost and utilization of genetic testing. Three themes emerged across cases: (1) choosing the most appropriate genetic test, (2) choosing the best person to test, and (3) interpreting results accurately. These cases demonstrate that involvement of a genetic counselor throughout the evaluation, diagnosis, and continuing management of individuals and families with inherited cardiovascular conditions helps to promote the efficient use of healthcare dollars.

KCNJ2 mutation causes an adrenergic-dependent rectification abnormality with calcium sensitivity and ventricular arrhythmia.

BACKGROUND: KCNJ2 mutations are associated with a variety of inherited arrhythmia syndromes including catecholaminergic polymorphic ventricular tachycardia 3. OBJECTIVE: To characterize the detailed cellular mechanisms of the clinically recognized KCNJ2 mutation R67Q. METHODS: Kir2.1 current density was measured from COS-1 cells transiently transfected with wild-type human Kir-2.1 (WT-Kir2.1) and/or a heterozygous missense mutation in KCNJ2 (R67Q-Kir2.1) by using the whole-cell voltage clamp technique. Catecholamine activity was simulated with protein kinase A-stimulating cocktail exposure. Phosphorylation-deficient mutants, S425N-Kir2.1 and S425N-Kir2.1/R67Q-S425N-Kir2.1, were used in a separate set of experiments. HA- or Myc-Tag-WT-Kir2.1 and HA-Tag-R67Q-Kir2.1 were used for confocal imaging. RESULTS: A 33-year-old woman presented with a catecholaminergic polymorphic ventricular tachycardia-like clinical phenotype and was found to have KCNJ2 missense mutation R67Q. Treatment with nadolol and flecainide resulted in the complete suppression of arrhythmias and symptom resolution. Under baseline conditions, R67Q-Kir2.1 expressed alone did not produce inward rectifier current while cells coexpressing WT-Kir2.1 and R67Q-Kir2.1 demonstrated the rectification index (RI) similar to that of WT-Kir2.1. After PKA stimulation, R67Q-Kir2.1/WT-Kir2.1 failed to increase peak outward current density; WT-Kir2.1 increased by 46% (n = 5), while R67Q-Kir2.1/WT-Kir2.1 decreased by 6% (n = 6) (P = .002). Rectification properties in R67Q-Kir2.1/WT-Kir2.1 demonstrated sensitivity to calcium with a decreased RI in the high-calcium pipette solution (RI 20.3% ± 4.1%) than in the low-calcium pipette solution (RI 36.5% ± 5.7%) (P < .05). Immunostaining of WT-Kir2.1 and R67Q-Kir2.1 individually and together showed a normal membrane expression pattern and colocalization by using the Pearson correlation coefficient. CONCLUSIONS: R67Q-Kir2.1 is associated with an adrenergic-dependent clinical and cellular phenotype with rectification abnormality enhanced by increased calcium. These findings are a significant advancement of our knowledge and understanding of the phenotype-genotype relationship of arrhythmia syndromes related to KCNJ2 mutations.

Atrial Fibrillation and Long QT Syndrome Presenting in a 12-Year-Old Girl.

Atrial fibrillation (AF) is rare in the pediatric population; however, there is increasing recognition that AF can be inherited. Long QT syndrome (LQTS), likewise, can be both acquired and inherited with mutations leading to abnormalities in cardiac ion channel function. Mutations in KCNQ1 are the most common cause of LQTS. Although rare, mutations in KCNQ1 also can cause familial AF. This report describes a child with a KCNQ1 missense mutation who uniquely expresses concomitant AF and LQTS. Due to the potential for increased morbidity and mortality, young patients who present with AF and a family history suggestive of inherited arrhythmias should trigger further investigation for LQTS and subsequent familial genetic counseling.

Task-oriented and bottle feeding adversely affect the quality of mother-infant interactions after abnormal newborn screens.

OBJECTIVE: To examine effects of newborn screening and neonatal diagnosis on the quality of mother-infant interactions in the context of feeding. METHODS: Study compared the quality of mother-infant feeding interactions among 4 groups of infants classified by severity of newborn screening and diagnostic results: cystic fibrosis (CF), congenital hypothyroidism, heterozygote CF carrier, and healthy with normal newborn screening. The Parent-Child Early Relational Assessment and a task-oriented item measured the quality of feeding interactions for 130 dyads, infant ages 3 to 19 weeks (M = 9.19, SD = 3.28). The Center for Epidemiologic Studies Depression Scale and State-Trait Anxiety Inventory measured maternal depression and anxiety. RESULTS: Composite Indicator Structure Equation Modeling showed that infant diagnostic status and, to a lesser extent, maternal education predicted feeding method. Mothers of infants with CF were most likely to bottle feed, which was associated with more task-oriented maternal behavior than breastfeeding. Mothers with low task-oriented behavior showed more sensitivity and responsiveness to infant cues, as well as less negative affect and behavior in their interactions with their infants than mothers with high task-oriented scores. Mothers of infants with CF were significantly more likely to have clinically significant anxiety and depression than the other groups. However, maternal psychological profile did not predict feeding method or interaction quality. CONCLUSIONS: Mothers in the CF group were the least likely to breastfeed. Research is needed to explicate long-term effects of feeding methods on quality of mother-child relationship and ways to promote continued breastfeeding after a neonatal CF diagnosis.