Phenotypic Divergence of JAG1- and NOTCH2-Associated Alagille Syndrome & Disease-Specific NOTCH2 Variant Classification Guidelines.

Background & Aims: Alagille syndrome (ALGS) is a rare, autosomal dominant disorder with high phenotypic heterogeneity. Disease-causing variants are primarily identified in Jagged1 (JAG1), with fewer reported in NOTCH2. JAG1 variants cause disease through a mechanism of haploinsufficiency, but the mechanism for NOTCH2 variants is not completely understood, making classification of variants more challenging.

Parents' perceptions of the utility of genetic testing in the NICU.

Purpose: Although several studies have evaluated the perspectives of parents in the neonatal intensive care unit on the utility of genetic testing in a research context and concluded with a positive appraisal, some data point to more varied perceptions.

Methods: Semistructured interviews were conducted to elicit parental beliefs about the ways in which clinical (nonresearch) genetic testing could be both helpful and harmful.

Results: We interviewed 43 parents of 36 neonates who were recommended and either accepted or declined to participate in clinical genetic testing.

How Neonatologists Use Genetic Information.

Objective: To delineate specific ways in which neonatologists integrate genetic information into their clinical decision making.

Study Design: We employed chart-stimulated recall, in which neonatologists described how they used genetic tests in specific patient cases, as well as semi-structured questioning about genetic information.

Results: Based on 28 interviews with neonatologists, we document 6 uses of genetic information: making a diagnosis, categorizing/stereotyping as "genetic," informing prognosis, influencing treatment, informing goals of care, and supporting accountability.

Generation of induced pluripotent stem cell lines TRNDi037-A and TRNDi038-A from two patients with Alagille syndrome carrying heterozygous JAG1 mutations.

Human induced pluripotent stem cell (iPSC) lines TRNDi037-A and TRNDi038-A were generated from the lymphoblastoid cell lines (LCL) of two patients with different heterozygous JAG1 variants resulting in Alagille syndrome (ALGS). ALGS is a rare genetic disease of haploinsufficiency that affects the formation of the bile duct, in addition to other symptoms. These ALGS iPSC lines can be used to model ALGS and aid in the identification of therapeutics to treat patients with ALGS.

Investigation of cryptic JAG1 splice variants as a cause of Alagille syndrome and performance evaluation of splice predictor tools.

Haploinsufficiency of JAG1 is the primary cause of Alagille syndrome (ALGS), a rare, multisystem disorder. The identification of JAG1 intronic variants outside of the canonical splice region as well as missense variants, both of which lead to uncertain associations with disease, confuses diagnostics. Strategies to determine whether these variants affect splicing include the study of patient RNA or minigene constructs, which are not always available or can be laborious to design, as well as the utilization of computational splice prediction tools.

Functional characterization of 2,832 JAG1 variants supports reclassification for Alagille syndrome and improves guidance for clinical variant interpretation.

Pathogenic variants in the JAG1 gene are a primary cause of the multi-system disorder Alagille syndrome. Although variant detection rates are high for this disease, there is uncertainty associated with the classification of missense variants that leads to reduced diagnostic yield. Consequently, up to 85% of reported JAG1 missense variants have uncertain or conflicting classifications.

Generation of an Alagille Syndrome (ALGS) patient-derived induced pluripotent stem cell line (TRNDi036-A) carrying a heterozygous mutation (p.Cys693*) in the JAG1 gene.

Alagille syndrome (ALGS) is an autosomal dominant, multisystemic disorder due to haploinsufficiency in JAG1 or less frequently, mutations in NOTCH2. The disease has been difficult to diagnose and treat due to variable expression. The generation of this iPSC line (TRNDi036-A) carrying a heterozygous mutation (p.

Human Mutation special issue on innovations in genomic diagnostics.

This special issue of Human Mutation focuses on Innovations in Genomic Diagnostics. The increasing interest in genomic medicine, and the growing possibilities for treatment and management of genetic disease, make complete and accurate diagnosis mission critical. This issue describes leading-edge technologies with emerging utility for genomic diagnostics.

Alagille syndrome and risk for hepatocellular carcinoma: Need for increased surveillance in adults with mild liver phenotypes.

Alagille syndrome (ALGS) is a multisystem autosomal dominant developmental disorder caused predominantly by pathogenic variants in JAGGED1 (JAG1), and also by pathogenic variants in NOTCH2 in a much smaller number of individuals. Clinical presentation is highly variable and includes liver, heart, eye, skeleton, and facial abnormalities, with a subset of individuals also presenting with kidney, vascular, and central nervous system phenotypes. Hepatocellular carcinoma (HCC) is a rare complication of ALGS, though little is known about its incidence or etiology among affected individuals.

Outcomes of Childhood Cholestasis in Alagille Syndrome: Results of a Multicenter Observational Study.

Alagille syndrome (ALGS) is an autosomal dominant multisystem disorder with cholestasis as a defining clinical feature. We sought to characterize hepatic outcomes in a molecularly defined cohort of children with ALGS-related cholestasis. Two hundred and ninety-three participants with ALGS with native liver were enrolled.

A six-attribute classification of genetic mosaicism.

Mosaicism denotes an individual who has at least two populations of cells with distinct genotypes that are derived from a single fertilized egg. Genetic variation among the cell lines can involve whole chromosomes, structural or copy-number variants, small or single-nucleotide variants, or epigenetic variants. The mutational events that underlie mosaic variants occur during mitotic cell divisions after fertilization and zygote formation.

Impaired Redox and Protein Homeostasis as Risk Factors and Therapeutic Targets in Toxin-Induced Biliary Atresia.

Background & Aims: Extrahepatic biliary atresia (BA) is a pediatric liver disease with no approved medical therapy. Recent studies using human samples and experimental modeling suggest that glutathione redox metabolism and heterogeneity play a role in disease pathogenesis. We sought to dissect the mechanistic basis of liver redox variation and explore how other stress responses affect cholangiocyte injury in BA.

A Centralized Approach for Practicing Genomic Medicine.

Next-generation sequencing has revolutionized the diagnostic process, making broadscale testing affordable and applicable to almost all specialties; however, there remain several challenges in its widespread implementation. Barriers such as lack of infrastructure or expertise within local health systems and complex result interpretation or counseling make it harder for frontline clinicians to incorporate genomic testing in their existing workflow. The general population is more informed and interested in pursuing genetic testing, and this has been coupled with the increasing accessibility of direct-to-consumer testing.

Exome Sequencing in Individuals with Isolated Biliary Atresia.

Biliary atresia (BA) is a severe pediatric liver disease resulting in necroinflammatory obliteration of the extrahepatic biliary tree. BA presents within the first few months of life as either an isolated finding or with additional syndromic features. The etiology of isolated BA is unknown, with evidence for infectious, environmental, and genetic risk factors described.

Protein-elongating mutations in MYH11 are implicated in a dominantly inherited smooth muscle dysmotility syndrome with severe esophageal, gastric, and intestinal disease.

Gastrointestinal motility disorders include a spectrum of mild to severe clinical phenotypes that are caused by smooth muscle dysfunction. We investigated the genetic etiology of severe esophageal, gastric, and colonic dysmotility in two unrelated families with autosomal dominant disease presentation. Using exome sequencing, we identified a 2 base pair insertion at the end of the myosin heavy chain 11 (MYH11) gene in all affected members of Family 1 [NM_001040113:c.

Alagille syndrome mutation update: Comprehensive overview of JAG1 and NOTCH2 mutation frequencies and insight into missense variant classification.

Alagille syndrome is an autosomal dominant disease with a known molecular etiology of dysfunctional Notch signaling caused primarily by pathogenic variants in JAGGED1 (JAG1), but also by variants in NOTCH2. The majority of JAG1 variants result in loss of function, however disease has also been attributed to lesser understood missense variants. Conversely, the majority of NOTCH2 variants are missense, though fewer of these variants have been described.

Use of a Dynamic Genetic Testing Approach for Childhood-Onset Epilepsy.

Importance: Although genetic testing is important for bringing precision medicine to children with epilepsy, it is unclear what genetic testing strategy is best in maximizing diagnostic yield.

Objectives: To evaluate the diagnostic yield of an exome-based gene panel for childhood epilepsy and discuss the value of follow-up testing.

Design, Setting, And Participants: A case series study was conducted on data from clinical genetic testing at Children's Hospital of Philadelphia was conducted from September 26, 2016, to January 8, 2018.