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

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.Cys693*) in the JAG1 gene provides a means of studying the disease and developing novel therapeutics towards patient treatment.

Dual Deletion of Keap1 and Rbpjκ Genes in Liver Leads to Hepatomegaly and Hypercholesterolemia

The hepatic deletion of Rbpjκ (RbpjF/F::AlbCre) in the mouse leads to exhibition of the Alagille syndrome phenotype during early postnatal liver development with hyperlipidemia and cholestasis due to attenuated disruption of NOTCH signaling. Given the roles of NRF2 signaling in the regulation of lipid metabolism and bile ductal formation, it was anticipated that these symptoms could be alleviated by enhancing NRF2 signaling in the RbpjF/F::AlbCre mouse by hepatic deletion of Keap1 in compound Keap1F/F::RbpjF/F::AlbCre mice. Unexpectedly, these mice developed higher hepatic and plasma cholesterol levels with more severe cholestatic liver damage during the pre-weaning period than in the RbpjF/F::AlbCre mice. In addition, hypercholesterolemia and hepatic damage were sustained throughout the growth period unlike in the RbpjF/F::AlbCre mouse. These enhanced abnormalities in lipid metabolism appear to be due to NRF2-dependent changes in gene expression related to cholesterol synthetic and subsequent bile acid production pathways. Notably, the hepatic expression of Cyp1A7 and Abcb11 genes involved in bile acid homeostasis was significantly reduced in Keap1F/F::RbpjF/F::AlbCre compared to RbpjF/F::AlbCre mice. The accumulation of liver cholesterol and the weakened capacity for bile excretion during the 3 pre-weaning weeks in the Keap1F/F::RbpjF/F::AlbCre mice may aggravate hepatocellular damage level caused by both excessive cholesterol and residual bile acid toxicity in hepatocytes. These results indicate that a tuned balance of NOTCH and NRF2 signaling is of biological importance for early liver development after birth.

UK guideline on the transition and management of childhood liver diseases in adulthood

INTRODUCTION

Improved outcomes of liver disease in childhood and young adulthood have resulted in an increasing number of young adults (YA) entering adult liver services. The adult hepatologist therefore requires a working knowledge in diseases that arise almost exclusively in children and their complications in adulthood.

AIMS

To provide adult hepatologists with succinct guidelines on aspects of transitional care in YA relevant to key disease aetiologies encountered in clinical practice.

METHODS

A systematic literature search was undertaken using the Pubmed, Medline, Web of Knowledge and Cochrane database from 1980 to 2023. MeSH search terms relating to liver diseases ('cholestatic liver diseases', 'biliary atresia', 'metabolic', 'paediatric liver diseases', 'autoimmune liver diseases'), transition to adult care ('transition services', 'young adult services') and adolescent care were used. The quality of evidence and the grading of recommendations were appraised using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system.

RESULTS

These guidelines deal with the transition of YA and address key aetiologies for the adult hepatologist under the following headings: (1) Models and provision of care; (2) screening and management of mental health disorders; (3) aetiologies; (4) timing and role of liver transplantation; and (5) sexual health and fertility.

CONCLUSIONS

These are the first nationally developed guidelines on the transition and management of childhood liver diseases in adulthood. They provide a framework upon which to base clinical care, which we envisage will lead to improved outcomes for YA with chronic liver disease.

JAG1 Variants Confer Genetic Susceptibility to Thyroid Dysgenesis and Thyroid Dyshormonogenesis in 813 Congenital Hypothyroidism in China

Background and Objective

Congenital hypothyroidism (CH) is indeed a prevalent neonatal endocrine disorder, affecting approximately 1 in 2000-3000 newborns worldwide, and 1 in 2400 newborns in China. Despite its high incidence, the genetic causes of CH, particularly those related to thyroid dysgenesis (TD), are still not well understood. However, previous studies have suggested that JAG1 may be a potential susceptibility gene for congenital thyroid defects. To explore the association between JAG1 and CH, we screened JAG1 variants in a large cohort of 813 CH patients.

Methods

We performed genetic analysis of JAG1 using next-generation sequencing in 813 CH cases. The pathogenicity of the variants was assessed by bioinformatics softwares, protein sequence conservation analysis, and hydrophobic analysis. Further genetic analysis was conducted targeting 20 CH-related genes in these 25 JAG1 variant carriers.

Results

We identified 10 pathogenic missense mutations (p.V45L, p.V272I, p.P552L, p.G610E, p.G852D, p.A891T, p.E1030K, p.R1060W, p.A1131T, p.P1174L) carried by 25 patients, the mutation rate of JAG1 in CH was 3.08%. Among these 25 patients, 16 with 1 variant, 6 with 2 variants, and the other 3 with 3 variants. Our findings indicated that JAG1 variants confer genetic susceptibility to both TD and DH, but with different inheritance models. JAG1 variants lead to TD mainly through monogenic model, while for DH cases, both monogenic mechanisms and oligogenic mechanisms play a pivotal role. Oligogenicity may contribute to the disease severity of DH.

Conclusion

JAG1 is a shared genetic factor in TD and DH, with a detection rate of 3.08% in Chinese individuals with CH. A comparison between the oligogenic and monogenic groups suggests a gene dosage effect in CH. Patients with the same JAG1 mutation exhibit diverse clinical phenotypes, indicating complex mechanisms underlying phenotypic heterogeneity.

THREE-YEAR FOLLOW-UP OF PROGRESSIVE CHORIORETINAL ATROPHY IN ATYPICAL ALAGILLE SYNDROME: A CASE REPORT

PURPOSE

To report a case of atypical Alagille syndrome with progressive chorioretinal atrophy.

METHODS

Case Report.

RESULTS

A 42-year-old Japanese man presented with atypical Alagille syndrome. At the first visit, funduscopy revealed anterior circumferential chorioretinal atrophy in the peripheral retina and peripapillary region with posterior pole sparing in both eyes. Fundus autofluorescence showed hypoautofluorescence in the peripheral and peripapillary regions, but normal findings in the macular region. After follow-up for 3 years, hypopigmented area with well visualized large choroidal vessels extended to mid-peripheral region. On Fundus autofluorescence images, hypoautofluorescence newly appeared in macular region in both eyes. Perivascular hypoautofluorescence and granular hyperautofluorescence scattering within the posterior pole were also observed. BCVA deteriorated and concentric visual field contraction worsened progressively.

CONCLUSION

Alagille syndrome is known to have many ophthalmic manifestations, most of which are stable with minimal threat to vision. In the present case, chorioretinal atrophy progressed during 3-year follow-up, suggesting that progression of chorioretinal atrophy with vision loss may occur over time in Alagille syndrome.

Jagged-mediated development and disease: Mechanistic insights and therapeutic implications for Alagille syndrome

Notch signaling controls multiple aspects of embryonic development and adult homeostasis. Alagille syndrome is usually caused by a single mutation in the jagged canonical Notch ligand 1 (JAG1), and manifests with liver disease and cardiovascular symptoms that are a direct consequence of JAG1 haploinsufficiency. Recent insights into Jag1/Notch-controlled developmental and homeostatic processes explain how pathology develops in the hepatic and cardiovascular systems and, together with recent elucidation of mechanisms modulating liver regeneration, provide a basis for therapeutic efforts. Importantly, disease presentation can be regulated by genetic modifiers, that may also be therapeutically leverageable. Here, we summarize recent insights into how Jag1 controls processes of relevance to Alagille syndrome, focused on Jag1/Notch functions in hepatic and cardiovascular development and homeostasis.

Pediatric Cholestatic Diseases: Common and Unique Pathogenic Mechanisms

Cholestasis is the predominate feature of many pediatric hepatobiliary diseases. The physiologic flow of bile requires multiple complex processes working in concert. Bile acid (BA) synthesis and excretion, the formation and flow of bile, and the enterohepatic reuptake of BAs all function to maintain the circulation of BAs, a key molecule in lipid digestion, metabolic and cellular signaling, and, as discussed in the review, a crucial mediator in the pathogenesis of cholestasis. Disruption of one or several of these steps can result in the accumulation of toxic BAs in bile ducts and hepatocytes leading to inflammation, fibrosis, and, over time, biliary and hepatic cirrhosis. Biliary atresia, progressive familial intrahepatic cholestasis, primary sclerosing cholangitis, and Alagille syndrome are four of the most common pediatric cholestatic conditions. Through understanding the commonalities and differences in these diseases, the important cellular mechanistic underpinnings of cholestasis can be greater appreciated.

Novel JAG1 variants leading to Alagille syndrome in two Chinese cases

Alagille Syndrome (ALGS) is a complex genetic disorder characterized by cholestasis, congenital cardiac anomalies, and butterfly vertebrae. The variable phenotypic expression of ALGS can lead to challenges in accurately diagnosing affected infants, potentially resulting in misdiagnoses or underdiagnoses. This study highlights novel JAG1 gene mutations in two cases of ALGS. The first case with a novel p.Pro325Leufs*87 variant was diagnosed at 2 months of age and exhibited a favorable prognosis and an unexpected manifestation of congenital hypothyroidism. Before the age of 2, the second patient was incorrectly diagnosed with liver structural abnormalities, necessitating extensive treatment. In addition, he exhibited delays in language acquisition that may have been a result of SNAP25 haploinsufficiency. The identification of ALGS remains challenging, highlighting the importance of early detection and genetic testing for effective patient management. The variant p.Pro325Leufs*87 is distinct from reported variants linked to congenital hypothyroidism in ALGS patients, thereby further confirming the clinical and genetic complexity of ALGS. This emphasizes the critical need for individualized and innovative approaches to diagnosis and medical interventions, uniquely intended to address the complexity of this syndrome.

Human Genetics of Semilunar Valve and Aortic Arch Anomalies

Lesions of the semilunar valve and the aortic arch can occur either in isolation or as part of well-described clinical syndromes. The polygenic cause of calcific aortic valve disease will be discussed including the key role of NOTCH1 mutations. In addition, the complex trait of bicuspid aortic valve disease will be outlined, both in sporadic/familial cases and in the context of associated syndromes, such as Alagille, Williams, and Kabuki syndromes. Aortic arch abnormalities particularly coarctation of the aorta and interrupted aortic arch, including their association with syndromes such as Turner and 22q11 deletion, respectively, are also discussed. Finally, the genetic basis of congenital pulmonary valve stenosis is summarized, with particular note to Ras-/mitogen-activated protein kinase (Ras/MAPK) pathway syndromes and other less common associations, such as Holt-Oram syndrome.

Generation of an Alagille syndrome (ALGS) patient-derived induced pluripotent stem cell line (TRNDi032-A) carrying a heterozygous mutation (p.Cys682Leufs*7) in the JAG1 gene

Alagille syndrome (ALGS) is an autosomal dominant, multisystemic disorder due to haploinsufficiency in either the JAG1 gene (ALGS type 1) or the NOTCH2 gene (ALGS type 2). The disease has been difficult to diagnose and treat due to its muti-system clinical presentation, variable expressivity, and prenatal onset for some of the features. The generation of this iPSC line (TRNDi032-A) carrying a heterozygous mutation, p.Cys682Leufs*7 (c.2044dup), in the JAG1 gene provides a means of studying the disease and developing novel therapeutics towards patient treatment.

ASO silencing of a glycosyltransferase, Poglut1 , improves the liver phenotypes in mouse models of Alagille syndrome

BACKGROUND AND AIMS

Paucity of intrahepatic bile ducts (BDs) is caused by various etiologies and often leads to cholestatic liver disease. For example, in patients with Alagille syndrome (ALGS), which is a genetic disease primarily caused by mutations in jagged 1 ( JAG1) , BD paucity often results in severe cholestasis and liver damage. However, no mechanism-based therapy exists to restore the biliary system in ALGS or other diseases associated with BD paucity. Based on previous genetic observations, we investigated whether postnatal knockdown of the glycosyltransferase gene protein O -glucosyltransferase 1 ( Poglut1) can improve the ALGS liver phenotypes in several mouse models generated by removing one copy of Jag1 in the germline with or without reducing the gene dosage of sex-determining region Y-box 9 in the liver.

APPROACH AND RESULTS

Using an ASO established in this study, we show that reducing Poglut1 levels in postnatal livers of ALGS mouse models with moderate to profound biliary abnormalities can significantly improve BD development and biliary tree formation. Importantly, ASO injections prevent liver damage in these models without adverse effects. Furthermore, ASO-mediated Poglut1 knockdown improves biliary tree formation in a different mouse model with no Jag1 mutations. Cell-based signaling assays indicate that reducing POGLUT1 levels or mutating POGLUT1 modification sites on JAG1 increases JAG1 protein level and JAG1-mediated signaling, suggesting a likely mechanism for the observed in vivo rescue.

CONCLUSIONS

Our preclinical studies establish ASO-mediated POGLUT1 knockdown as a potential therapeutic strategy for ALGS liver disease and possibly other diseases associated with BD paucity.

Characterization of an induced pluripotent stem cell line NCHi011-A from a 23-year-old female with Alagille Syndrome harboring a heterozygous JAG1 pathogenic variant

Alagille syndrome (ALGS) is a multisystem disease with high variability in clinical features. ALGS is predominantly caused by pathogenic variants in the Notch ligand JAG1. An iPSC line, NCHi011-A, was generated from a ALGS patient with complex cardiac phenotypes consisting of pulmonic valve and branch pulmonary artery stenosis. NCHi011-A is heterozygous for a single base duplication causing a frameshift in the JAG1 gene. This iPSC line demonstrates normal cellular morphology, expression of pluripotency markers, trilineage differentiation potential, and identity to the source patient. NCHi011-A provides a resource for modeling ALGS and investigating the role of Notch signaling in the disease.

Management of adults with Alagille syndrome

Alagille syndrome (ALGS) is a complex rare genetic disorder that involves multiple organ systems and is historically regarded as a disease of childhood. Since it is inherited in an autosomal dominant manner in 40% of patients, it carries many implications for genetic counselling of patients and screening of family members. In addition, the considerable variable expression and absence of a clear genotype-phenotype correlation, results in a diverse range of clinical manifestations, even in affected individuals within the same family. With recent therapeutic advancements in cholestasis treatment and the improved survival rates with liver transplantation (LT), many patients with ALGS survive into adulthood. Although LT is curative for liver disease secondary to ALGS, complications secondary to extrahepatic involvement remain problematic lifelong. This review is aimed at providing a comprehensive review of ALGS to adult clinicians who will take over the medical care of these patients following transition, with particular focus on certain aspects of the condition that require lifelong surveillance. We also provide a diagnostic framework for adult patients with suspected ALGS and highlight key aspects to consider when determining eligibility for LT in patients with this syndrome.

Generation of iPSC line NCHi012-A from a patient with Alagille syndrome and heterozygous pathogenic variant in the JAG1 gene

Alagille syndrome (ALGS) is an autosomal dominant disease affecting the liver, heart and other organs with high variability. About 95% of ALGS cases are associated with pathogenic variants in JAG1, encoding the Jagged1 ligand that binds to Notch receptors. The iPSC line NCHi012-A was derived from an ALGS patient with cholestatic liver disease and mild pulmonary stenosis, who is heterozygous for a 2 bp deletion in the JAG1 coding sequence. We report here an initial characterization of NCHi012-A to evaluate its morphology, pluripotency, differentiation potential, genotype, karyotype and identity to the source patient.

Clinical Characterization of Alagille Syndrome in Patients with Cholestatic Liver Disease

Alagille syndrome (ALGS) is a multisystem condition characterized by cholestasis and bile duct paucity on liver biopsy and variable involvement of the heart, skeleton, eyes, kidneys, and face and caused by pathogenic variants in the JAG1 or NOTCH2 gene. The variable expressivity of the clinical phenotype and the lack of genotype-phenotype correlations lead to significant diagnostic difficulties. Here we present an analysis of 18 patients with cholestasis who were diagnosed with ALGS. We used an NGS panel targeting coding exons of 52 genes, including the JAG1 and NOTCH2 genes. Sanger sequencing was used to verify the mutation in the affected individuals and family members. The specific facial phenotype was seen in 16/18 (88.9%). Heart defects were seen in 8/18 (44.4%) patients (pulmonary stenosis in 7/8). Butterfly vertebrae were seen in 5/14 (35.7%) patients. Renal involvement was detected in 2/18 (11.1%) cases-one patient had renal cysts, and one had obstructive hydronephrosis. An ophthalmology examination was performed on 12 children, and only one had posterior embryotoxon (8.3%). A percutaneous liver biopsy was performed in nine cases. Bile duct paucity was detected in six/nine cases (66.7%). Two patients required liver transplantation because of cirrhosis. We identified nine novel variants in the JAG1 gene-eight frameshift variants (c.1619_1622dupGCTA (p.Tyr541X), c.1160delG (p.Gly387fs), c.964dupT (p.C322fs), c.120delG (p.L40fs), c.1984dupG (p.Ala662Glyfs), c.3168_3169delAG (p.R1056Sfs*51), c.2688delG (p.896CysfsTer49), c.164dupG (p.Cys55fs)) and one missense variant, c.2806T > G (p.Cys936Gly). None of the patients presented with NOTCH2 variants. In accordance with the classical criteria, only six patients could meet the diagnostic criteria in our cohort without genetic analysis. Genetic testing is important in the diagnosis of ALGS and can help differentiate it from other types of cholestasis.

Poly-hydroxylated bile acids and their prognostic roles in Alagille syndrome

BACKGROUND

The liver manifestations of Alagille syndrome (ALGS) are highly variable, and factors affecting its prognosis are poorly understood. We asked whether the composition of bile acids in ALGS patients with good clinical outcomes differs from that in patients with poor outcomes and whether bile acids could be used as prognostic biomarkers.

METHODS

Blood for bile acid profiling was collected from genetically confirmed JAG1-associated ALGS patients before one year of age. A good prognosis was defined as survival with native liver and total bilirubin (TB) < 85.5 μmol/L, while a poor prognosis was defined as either liver transplantation, death from liver failure, or TB ≥ 85.5 μmol/L at the last follow-up.

RESULTS

We found that the concentrations of two poly-hydroxylated bile acids, tauro-2β,3α,7α,12α-tetrahydroxylated bile acid (THBA) and glyco-hyocholic acid (GHCA), were significantly increased in patients with good prognosis compared to those with poor prognosis [area under curve (AUC) = 0.836 and 0.782, respectively] in the discovery cohort. The same trend was also observed in the molar ratios of GHCA to glyco- chenodeoxycholic acid (GCDCA) and tetrahydroxylated bile acid (THCA) to tauro-chenodeoxycholic acid (TCDCA) (both AUC = 0.836). A validation cohort confirmed these findings. Notably, tauro-2β,3α,7α,12α-THBA achieved the highest prediction accuracy of 88.00% (92.31% sensitivity and 83.33% specificity); GHCA at > 607.69 nmol/L was associated with native liver survival [hazard ratio: 13.03, 95% confidence interval (CI): (2.662-63.753), P = 0.002].

CONCLUSIONS

We identified two poly-hydroxylated bile acids as liver prognostic biomarkers of ALGS patients. Enhanced hydroxylation of bile acids may result in better clinical outcomes.

Alagille syndrome: understanding the genotype-phenotype relationship and its potential therapeutic impact

INTRODUCTION

Alagille syndrome (ALGS) is an autosomal dominant, multisystem genetic disorder with wide phenotypic variability caused by mutations in the Notch signaling pathway, specifically from mutations in either the Jagged1 (JAG1) or NOTCH2 gene. The range of clinical features in ALGS can involve various organ systems including the liver, heart, eyes, skeleton, kidney, and vasculature. Despite the genetic mutations being well-defined, there is variable expressivity and individuals with the same mutation may have different clinical phenotypes.

AREAS COVERED

While no clear genotype-phenotype correlation has been identified in ALGS, this review will summarize what is currently known about the genotype-phenotype relationship and how this relationship influences the treatment of the multisystemic disorder. This review includes discussion of numerous studies which have focused on describing the genotype-phenotype relationship of different organ systems in ALGS as well as relevant basic science and population studies of ALGS. A thorough literature search was completed via the PubMed and National Library of Medicine GeneReviews databases including dates from 1969, when ALGS was first identified, to February 2023.

EXPERT OPINION

The genetics of ALGS are well defined; however, ongoing investigation to identify genotype-phenotype relationships as well as genetic modifiers as potential therapeutic targets is needed. Clinicians and patients alike would benefit from identification of a correlation to aid in diagnostic evaluation and management.

Exome-wide assessment of isolated biliary atresia: A report from the National Birth Defects Prevention Study using child-parent trios and a case-control design to identify novel rare variants

The etiology of biliary atresia (BA) is unknown, but recent studies suggest a role for rare protein-altering variants (PAVs). Exome sequencing data from the National Birth Defects Prevention Study on 54 child-parent trios, one child-mother duo, and 1513 parents of children with other birth defects were analyzed. Most (91%) cases were isolated BA. We performed (1) a trio-based analysis to identify rare de novo, homozygous, and compound heterozygous PAVs and (2) a case-control analysis using a sequence kernel-based association test to identify genes enriched with rare PAVs. While we replicated previous findings on PKD1L1, our results do not suggest that recurrent de novo PAVs play important roles in BA susceptibility. In fact, our finding in NOTCH2, a disease gene associated with Alagille syndrome, highlights the difficulty in BA diagnosis. Notably, IFRD2 has been implicated in other gastrointestinal conditions and warrants additional study. Overall, our findings strengthen the hypothesis that the etiology of BA is complex.

Genetic alterations and molecular mechanisms underlying hereditary intrahepatic cholestasis

Hereditary cholestatic liver disease caused by a class of autosomal gene mutations results in jaundice, which involves the abnormality of the synthesis, secretion, and other disorders of bile acids metabolism. Due to the existence of a variety of gene mutations, the clinical manifestations of children are also diverse. There is no unified standard for diagnosis and single detection method, which seriously hinders the development of clinical treatment. Therefore, the mutated genes of hereditary intrahepatic cholestasis were systematically described in this review.

Morphological aspects of small-duct cholangiopathies: A minireview

The biliary system consists of intrahepatic and extrahepatic bile ducts lined by biliary epithelial cells (cholangiocytes). Bile ducts and cholangiocytes are affected by a variety of disorders called cholangiopathies, which differ in aetiology, pathogenesis, and morphology. Classification of cholangiopathies is complex and reflects pathogenic mechanisms (immune-mediated, genetic, drug- and toxin-induced, ischaemic, infectious, neoplastic), predominant morphological patterns of biliary injury (suppurative and non-suppurative cholangitis, cholangiopathy), and specific segments of the biliary tree affected by the disease process. While the involvement of large extrahepatic and intrahepatic bile ducts is typically visualised using radiology imaging, histopathological examination of liver tissue obtained by percutaneous liver biopsy still plays an important role in the diagnosis of cholangiopathies affecting the small intrahepatic bile ducts. To increase the diagnostic yield of a liver biopsy and determine the optimal therapeutic approach, the referring clinician is tasked with interpreting the results of histopathological examination. This requires knowledge and understanding of basic morphological patterns of hepatobiliary injury and an ability to correlate microscopic findings with results obtained by imaging and laboratory methods. This minireview describes the morphological aspects of small-duct cholangiopathies pertaining to the diagnostic process.

Defective jagged-1 signaling affects GnRH development and contributes to congenital hypogonadotropic hypogonadism

In vertebrate species, fertility is controlled by gonadotropin-releasing hormone (GnRH) neurons. GnRH cells arise outside the central nervous system, in the developing olfactory pit, and migrate along olfactory/vomeronasal/terminal nerve axons into the forebrain during embryonic development. Congenital hypogonadotropic hypogonadism (CHH) and Kallmann syndrome are rare genetic disorders characterized by infertility, and they are associated with defects in GnRH neuron migration and/or altered GnRH secretion and signaling. Here, we documented the expression of the jagged-1/Notch signaling pathway in GnRH neurons and along the GnRH neuron migratory route both in zebrafish embryos and in human fetuses. Genetic knockdown of the zebrafish ortholog of JAG1 (jag1b) resulted in altered GnRH migration and olfactory axonal projections to the olfactory bulbs. Next-generation sequencing was performed in 467 CHH unrelated probands, leading to the identification of heterozygous rare variants in JAG1. Functional in vitro validation of JAG1 mutants revealed that 7 out of the 9 studied variants exhibited reduced protein levels and altered subcellular localization. Together our data provide compelling evidence that Jag1/Notch signaling plays a prominent role in the development of GnRH neurons, and we propose that JAG1 insufficiency may contribute to the pathogenesis of CHH in humans.

Identification of Novel Risk Variants of Non-Syndromic Cleft Palate by Targeted Gene Panel Sequencing

Non-syndromic cleft palate (ns-CP) has a genetically heterogeneous aetiology. Numerous studies have suggested a crucial role of rare coding variants in characterizing the unrevealed component of genetic variation in ns-CP called the "missing heritability". Therefore, this study aimed to detect low-frequency variants that are implicated in ns-CP aetiology in the Polish population. For this purpose, coding regions of 423 genes associated with orofacial cleft anomalies and/or involved with facial development were screened in 38 ns-CP patients using the next-generation sequencing technology. After multistage selection and prioritisation, eight novel and four known rare variants that may influence an individual's risk of ns-CP were identified. Among detected alternations, seven were located in novel candidate genes for ns-CP, including COL17A1 (c.2435-1G>A), DLG1 (c.1586G>C, p.Glu562Asp), NHS (c.568G>C, p.Val190Leu-de novo variant), NOTCH2 (c.1997A>G, p.Tyr666Cys), TBX18 (c.647A>T, p.His225Leu), VAX1 (c.400G>A, p.Ala134Thr) and WNT5B (c.716G>T, p.Arg239Leu). The remaining risk variants were identified within genes previously linked to ns-CP, confirming their contribution to this anomaly. This list included ARHGAP29 (c.1706G>A, p.Arg569Gln), FLNB (c.3605A>G, Tyr1202Cys), IRF6 (224A>G, p.Asp75Gly-de novo variant), LRP6 (c.481C>A, p.Pro161Thr) and TP63 (c.353A>T, p.Asn118Ile). In summary, this study provides further insights into the genetic components contributing to ns-CP aetiology and identifies novel susceptibility genes for this craniofacial anomaly.

Clinical and Genetic Characteristics of Alagille Syndrome in Adults

BACKGROUND AND AIMS

Alagille syndrome (AGS) is an autosomal dominant multisystem disorder caused by mutations in the JAG1 and NOTCH2 genes. AGS has been rarely reported in adult patients, mainly because its characteristics in adults are subtle. The study aimed to improve the understanding of adult AGS by a descriptive case series.

METHODS

Eight adults diagnosed with AGS at our hospital between June 2016 and June 2019 were included in the study. Clinical data, biochemical results, imaging results, liver histopathology, and genetic testing were analyzed.

RESULTS

Three female and five male patients with a median age of 24.5 years at the time of diagnosis were included in the analysis. The clinical manifestations were adult-onset (62.5%, 5/8), cholestasis (50%, 4/8), butterfly vertebrae (62.5%, 5/8), systolic murmurs (12.5%, 1/8), typical facies (12.5%, 1/8), posterior embryotoxon, and renal abnormalities (0/8). Genetic sequencing showed that all patients had mutations, with four occurring in the JAG1 gene and four in the NOTCH2 gene. Six were substitution mutations, one was a deletion mutation, and one was a splicing mutation. Five had been previously reported; but the others, one JAG1 mutation and two NOTCH2 mutations were unique and are reported here for the first time.

CONCLUSIONS

The clinical manifestations highlighted by the current diagnostic criteria for most adults with AGS are atypical. Those who do not meet the criteria but are highly suspicious of having AGS need further evaluation, especially genetic testing.

Natural history of liver disease in a large international cohort of children with Alagille syndrome: Results from the GALA study

BACKGROUND AND AIMS

Alagille syndrome (ALGS) is a multisystem disorder, characterized by cholestasis. Existing outcome data are largely derived from tertiary centers, and real-world data are lacking. This study aimed to elucidate the natural history of liver disease in a contemporary, international cohort of children with ALGS.

APPROACH AND RESULTS

This was a multicenter retrospective study of children with a clinically and/or genetically confirmed ALGS diagnosis, born between January 1997 and August 2019. Native liver survival (NLS) and event-free survival rates were assessed. Cox models were constructed to identify early biochemical predictors of clinically evident portal hypertension (CEPH) and NLS. In total, 1433 children (57% male) from 67 centers in 29 countries were included. The 10 and 18-year NLS rates were 54.4% and 40.3%. By 10 and 18 years, 51.5% and 66.0% of children with ALGS experienced ≥1 adverse liver-related event (CEPH, transplant, or death). Children (>6 and ≤12 months) with median total bilirubin (TB) levels between ≥5.0 and <10.0 mg/dl had a 4.1-fold (95% confidence interval [CI], 1.6-10.8), and those ≥10.0 mg/dl had an 8.0-fold (95% CI, 3.4-18.4) increased risk of developing CEPH compared with those <5.0 mg/dl. Median TB levels between ≥5.0 and <10.0 mg/dl and >10.0 mg/dl were associated with a 4.8 (95% CI, 2.4-9.7) and 15.6 (95% CI, 8.7-28.2) increased risk of transplantation relative to <5.0 mg/dl. Median TB <5.0 mg/dl were associated with higher NLS rates relative to ≥5.0 mg/dl, with 79% reaching adulthood with native liver ( p < 0.001).

CONCLUSIONS

In this large international cohort of ALGS, only 40.3% of children reach adulthood with their native liver. A TB <5.0 mg/dl between 6 and 12 months of age is associated with better hepatic outcomes. These thresholds provide clinicians with an objective tool to assist with clinical decision-making and in the evaluation of therapies.

Isolated aneurysmal disease as an underestimated finding in individuals with JAG1 pathogenic variants

Pathogenic variants in JAG1 are known to cause Alagille syndrome (ALGS), a disorder that primarily affects the liver, lung, kidney, and skeleton. Whereas cardiac symptoms are also frequently observed in ALGS, thoracic aortic aneurysms have only been reported sporadically in postmortem autopsies. We here report two families with segregating JAG1 variants that present with isolated aneurysmal disease, as well as the first histological evaluation of aortic aneurysm tissue of a JAG1 variant carrier. Our observations shed more light on the pathomechanisms behind aneurysm formation in JAG1 variant harboring individuals and underline the importance of cardiovascular imaging in the clinical follow-up of such individuals.

Case Report: Novel JAG1 gene mutations in two infants with alagille syndrome characterized by cholestasis

Background

Infants with Alagille syndrome (ALGS) need to be promptly differentiated from biliary atresia (BA) at an early stage. ALGS is an autosomal, dominant, multisystem disorder with variable phenotypic penetrance caused by heterozygous mutations in JAG1 or NOTCH2, which encode the Notch signaling pathway.

Case presentation

We report two cases, both with cholestatic jaundice as the main manifestation, in which BA was excluded and finally diagnosed as ALGS based on characteristic facial features, serological tests, imaging, laparoscopic cholangiography, pathology and genetic findings. Both cases are novel mutant genes on chromosome 20 that have not been reported in the literature. The mutation in patient 1 was a novel heterozygous nonsense mutation (NM_000214 exon20, c.2419G > T, p.E807Ter), which was a spontaneous mutation. Followed up to 1 year and 6 months, the symptoms resolved with ursodeoxycholic acid and cholestyramine, and the jaundice has now subsided. Patient 2 was a novel heterozygous frameshift mutation (NM_000214 exon19, c.2367-2368dupTC, p.P790Lfs*31), which was inherited from his mother. This patient was followed up to 9 months and is currently awaiting liver transplantation.

Conclusion

Both cholestatic infants reported combined to exclude BA, avoid Kasai portoenterostomy (KPE), and definitively diagnose ALGS. Broadening the spectrum of JAG1 gene mutations.

Alagille Syndrome: Current Understanding of Pathogenesis, and Challenges in Diagnosis and Management

Alagille syndrome (ALGS) is a complex heterogenous disease with a wide array of clinical manifestations in association with cholestatic liver disease. Major clinical and genetic advancements have taken place since its first description in 1969. However, clinicians continue to face considerable challenges in the management of ALGS, particularly in the absence of targeted molecular therapies. In this article, we provide an overview of the broad ALGS phenotype, current approaches to diagnosis and with particular focus on key clinical challenges encountered in the management of these patients.

Defining pathogenicity of NOTCH2 variants for diagnosis of Alagille syndrome type 2 using a large cohort of patients

BACKGROUND AND AIMS

Alagille syndrome (ALGS) type 2 caused by mutations in NOTCH2 has genotypic and phenotypic heterogeneity. Diagnosis in some atypical patients with isolated hepatic presentation could be missed.

METHODS

Using 2087 patients with paediatric liver manifestations, NOTCH2 allele frequencies, in-silico prediction, protein domains and clinical features were analysed to define the pathogenicity of NOTCH2 variants for diagnosis of ALGS type 2.

RESULTS

Among 2087 patients with paediatric liver manifestations, significantly more NOTCH2 variants were absent in gnomAD in patients with elevated γ-glutamyltransferase (GGT) (p = .041). Significantly more NOTCH2 variants which were absent in gnomAD were located in protein functional domains (p = .038). When missense variants were absent in gnomAD and predicted to be pathogenic by at least three out of seven in-silico tools, they were found to be significantly associated with liver manifestations with elevated GGT (p = .003). Comparing this to patients with likely benign (LB) variants, the patients with likely-pathogenic (LP) variants have significantly more liver manifestations with elevated GGT (p = .0001). Significantly more patients with LP variants had extra-hepatic phenotypes of ALGS compared with those patients with LB variants (p = .0004).

CONCLUSION

When NOTCH2 variants are absent in gnomAD, null variants and missense variants which were predicted to be pathogenic by at least three in-silico tools could be considered pathogenic in patients with high GGT chronic liver diseases.

De novo brain arteriovenous malformation formation and development: A case report

BACKGROUND

Brain arteriovenous malformation (AVM), an aberrant vascular development during the intrauterine period, is traditionally considered a congenital disease. Sporadic reports of cases of de novo AVM formation in children and adults have challenged the traditional view of its congenital origin.

CASE SUMMARY

In this report, we have presented the case of a child with a de novo brain AVM. Magnetic resonance imaging and magnetic resonance angiography of the brain showed no AVM at the age of 5 years and 2 mo. Brain AVM was first detected in this child at the age of 7 years and 4 mo. The brain AVM was significantly advanced, and hemorrhage was seen for the first time at the age of 12 years and 8 mo. There was further progression in the AVM, and hemorrhage occurred again at the age of 13 years and 5 mo. Genetic analysis of this patient revealed a mutation in the NOTCH2 (p.Asp473Val) gene.

CONCLUSION

In short, our case has once again confirmed the view that brain AVM is an acquired disease and is the result of the interaction of genes, environment, and molecules.

Cholestatic liver diseases of genetic etiology: Advances and controversies

With the application of modern investigative technologies, cholestatic liver diseases of genetic etiology are increasingly identified as the root cause of previously designated "idiopathic" adult and pediatric liver diseases. Here, we review advances in the field enhanced by a deeper understanding of the phenotypes associated with specific gene defects that lead to cholestatic liver diseases. There are evolving areas for clinicians in the current era specifically regarding the role for biopsy and opportunities for a "sequencing first" approach. Risk stratification based on the severity of the genetic defect holds promise to guide the decision to pursue primary liver transplantation versus medical therapy or nontransplant surgery, as well as early screening for HCC. In the present era, the expanding toolbox of recently approved therapies for hepatologists has real potential to help many of our patients with genetic causes of cholestasis. In addition, there are promising agents under study in the pipeline. Relevant to the current era, there are still gaps in knowledge of causation and pathogenesis and lack of fully accepted biomarkers of disease progression and pruritus. We discuss strategies to overcome the challenges of genotype-phenotype correlation and draw attention to the extrahepatic manifestations of these diseases. Finally, with attention to identifying causes and treatments of genetic cholestatic disorders, we anticipate a vibrant future of this dynamic field which builds upon current and future therapies, real-world evaluations of individual and combined therapeutics, and the potential incorporation of effective gene editing and gene additive technologies.

Novel phenotypic feature in a patient with a recurrent NOTCH2 nonsense mutation

Pathogenic variants in NOTCH2 which encodes a single-pass transmembrane protein have been identified as a cause of several autosomal dominant congenital disorders. In particular, truncating mutations in exon 34 have been found in patients with skeletal abnormalities and dysmorphic features. We describe a patient with a de novo variant in NOTCH2 who displayed features of both Hajdu-Cheney syndrome (HJCYS) and serpentine fibula-polycystic kidney syndrome (SFPKS). The recurrent nonsense variant in exon 34 has been reported in seven other patients with syndromic presentations, making it the most common pathogenic variant for NOTCH2 in congenital disorders. In addition to the core features of HJCYS and SFPKS, there was a gastrointestinal tract malformation of an imperforate anus which has not been reported in patients with pathogenic variants in NOTCH2.

Broadening the clinical spectrum of ALGS: an Egyptian cohort with five novel mutations in JAG1 gene

Background

Alagille syndrome (ALGS) is a rare autosomal dominant multisystem disorder that affects the liver, heart, eyes, vertebrae, and kidneys and is associated with characteristic facies. This work aimed to study the spectrum of the clinical features of ALGS in an Egyptian cohort of patients in conjunction with partial sequencing of the JAG1 gene.

Methods

This study included 17 pediatric ALGS patients diagnosed on clinical grounds: facial features, cholestatic liver disease, and cardiac, vertebral, and ocular findings. Molecular analysis was conducted in 10 selected exons of the JAG1 gene.

Results

The clinical features of ALGS included cholestatic liver disease (100%), facial dysmorphism (100%), cardiac abnormalities (88.2%), butterfly vertebrae (64.7%), posterior embryotoxon (35.2%), poor growth (41%), xanthomata (11.8%), and hiatus hernia (11.8%). Five novel pathogenic JAG1 mutations were identified in this study, including two nonsense mutations, one splicing mutation, one frameshift insertion, and one frameshift deletion. In two patients, the mutations were confirmed to be de novo, as the mutations could not be detected in both parents.

Conclusion

Five novel JAG1 pathogenic variants were identified in this study. This is the first molecular study to report pathogenic mutations in the JAG1 gene within an Egyptian cohort of children with ALGS.

A case of infantile Alagille syndrome with severe dyslipidemia: a new insight into lipid metabolism and therapeutics

Alagille syndrome (AGS) is an autosomal dominant genetic disorder characterized by congenital heart disease, hepatic cholestasis, dyslipidemia, and characteristic facies since infancy. Cholestatic hypercholesterolemia in patients diagnosed with AGS is occasionally refractory and resistant to conventional treatments. We report the case of a 4-month-old boy diagnosed with AGS and refractory dyslipidemia due to cholestatic liver disease. He had repeated episodes of cyanosis due to pulmonary artery atresia since birth and underwent a Blalock-Taussig shunt procedure at age 3 months. At age 4 months, cholestatic hyperbilirubinemia deteriorated to a serum total bilirubin level of 19.9 mg/dL. At age 12 months, a laboratory test revealed severe dyslipidemia (serum total cholesterol, 1796 mg/dL; serum triglycerides [TGs], 635 mg/dL), and the presence of xanthomas. A pathogenic variant of the JAG1 gene (c.1326G > A, p.Trp442X) was detected through genetic testing. Oral ursodeoxycholate normalized hyperbilirubinemia with a subtle improvement in dyslipidemia. Combination therapy with pravastatin and fenofibrate did not successfully improve dyslipidemia. At age 20 months, altering pravastatin to atorvastatin was effective in normalizing serum cholesterol and TGs with no adverse events.

Combination therapy with atorvastatin and fenofibrate was successful in improving refractory dyslipidemia in a child with AGS. Atorvastatin is a well-known strong statin that can lower serum cholesterol, and fenofibrate can lower serum TG levels. We propose that atorvastatin be taken into consideration for the treatment of persistent hyperlipidemia in patients diagnosed with AGS, because atorvastatin upregulates bile acid synthesis and lipoprotein scavenging, and inhibits intrinsic cholesterol production.

Alagille syndrome due to a de novo NOTCH2 mutation presenting as prenatal oligohydramnios and congenital bilateral renal hypodysplasia: A case report

INTRODUCTION

Here, we report the case of an infant suffering from Alagille syndrome (ALGS), manifesting with the atypical clinical manifestations of prenatal oligohydramnios and renal lesions. To the best of our knowledge, this is the first case of ALGS presenting as prenatal oligohydramnios and renal lesions caused by a de novo variant of the NOTCH2 gene.

CASE PRESENTATION

A 3-month-old male infant was hospitalized for severe malnutrition. He presented with prenatal oligohydramnios from 28⁺⁴ weeks of gestation. After birth, he failed to thrive and suffered from impaired motor development, thermoregulation disorders, congenital bilateral renal hypodysplasia, which initially manifested as stage 5 before improving to stage 3 chronic renal impairment, slightly elevated levels of transaminases, cholestasis, and dysmorphic facial features. We used a diagnostic screening panel of 4,047 pathogenic genes and whole exome sequencing (WES) to analyze the proband and his parents (who had normal kidneys). We found that the proband carried a de novo heterozygous splicing variant (c.5930-2A > G) in intron 33 of the NOTCH2 gene. Transcriptome sequencing confirmed that the mutation of this gene site would affect the splicing of NOTCH2 mRNA and lead to exon 33 skipping.

CONCLUSIONS

Our case expands the spectrum of pathogenic variants of the NOTCH2 gene that are known to be associated with ALGS and characterized by prenatal oligohydramnios and renal lesions. It also reminds us of the necessity to monitor the liver and kidney function of the infant if a mother has oligohydramnios during pregnancy and we recommend ALGS as an additional differential diagnosis in prenatal renal abnormalities.

Macular atrophy in JAG1-related Alagille syndrome: a case series

BACKGROUND

: Alagille syndrome (AS) is a multisystem disorder associated with a range of ocular anomalies affecting the anterior and posterior segments. While chorioretinal abnormalities have been reported in Alagille Syndrome, identification of macular dystrophy and detailed clinical and electrophysiologic descriptions are scarce.

MATERIALS AND METHODS

: A retrospective review was conducted to identify patients with a diagnosis of AS and retinal disease who were evaluated in the Division of Pediatric Ophthalmology, Strabismus, and Adult Motility at UPMC Children's Hospital of Pittsburgh. Criteria of AS included biopsy-proven bile duct hypoplasia, presence of major clinical features of AS, and molecular confirmation of the JAG1 gene.

RESULTS

: This cohort included three patients, two females and one male, diagnosed with JAG1-Alagille syndrome. The diagnosis was made before 2 years of life in all patients. The mean follow-up period in our center was 8 years. All patients were found to have retinal pigmentary changes, macular atrophy, choroidal thinning, optic disc anomalies, and progressive decrease in vision. Marked retinal and macular dysfunction were found in electrophysiological studies.

CONCLUSIONS

: Three patients with molecularly confirmed Alagille syndrome demonstrated unusual retinal and macular findings, with two showing progressive vision loss. Due to the rarity of retinal findings in AS and the observed progression of disease in our patients, clinical genetic testing for retinal dystrophies could be completed in two cases. These investigations failed to reveal a separate molecular cause for the observed retinal dystrophy, helping to confirm the association with JAG1-related AS.

Targeting Bone Metastases Signaling Pathway Using Moringa oleifera Seed Nutri-miRs: A Cross Kingdom Approach

Moringa oleifera is a medicinally important plant that has various medical and nutritional uses. Plant miRNAs are a class of non-coding endogenous small RNAs that regulate human-specific mRNA but the mechanistic actions are largely unknown. Here, in this study, we aim to explore the mechanistic action and influence of M. oleifera seed miRNAs on vital human target genes using computer based approaches. The M. oleifera seed miRNAs sequence was taken from published data and identified its human gene targets using a psRNA target analysis server. We identified 94 miRNAs that are able to significantly regulate 47 human target genes, which has enormous biological and functional importance. Out of 47 human targeted genes, 23 genes were found to be associated with PI3K-AKT, RUNX, and MAPK1/MAPK3 signaling pathway which has shown to play key roles in bone metastases during cancer progression. The M. oleifera seed miRNAs hold a strong potential for future research that might uncover the possibility of miRNA-facilitated cross-kingdom regulation and therapeutic targets for bone metastases.

Alagille Syndrome: A Focused Review on Clinical Features, Genetics, and Treatment

Alagille syndrome (ALGS) is an autosomal dominant disorder caused by pathogenic variants in JAG1 or NOTCH2, which encode fundamental components of the Notch signaling pathway. Clinical features span multiple organ systems including hepatic, cardiac, vascular, renal, skeletal, craniofacial, and ocular, and occur with variable phenotypic penetrance. Genotype-phenotype correlation studies have not yet shown associations between mutation type and clinical manifestations or severity, and it has been hypothesized that modifier genes may modulate the effects of JAG1 and NOTCH2 pathogenic variants. Medical management is supportive, focusing on clinical manifestations of disease, with liver transplant indicated for severe pruritus, liver synthetic dysfunction, portal hypertension, bone fractures, and/or growth failure. New therapeutic approaches are under investigation, including ileal bile acid transporter (IBAT) inhibitors and other approaches that may involve targeted interventions to augment the Notch signaling pathway in involved tissues.

Therapeutics Development for Alagille Syndrome

Advancements in treatment for the rare genetic disorder known as Alagille Syndrome (ALGS) have been regrettably slow. The large variety of mutations to the JAG1 and NOTCH2 genes which lead to ALGS pose a unique challenge for developing targeted treatments. Due to the central role of the Notch signaling pathway in several cancers, traditional treatment modalities which compensate for the loss in activity caused by mutation are rightly excluded. Unfortunately, current treatment plans for ALGS focus on relieving symptoms of the disorder and do not address the underlying causes of disease. Here we review several of the current and potential key technologies and strategies which may yield a significant leap in developing targeted therapies for this disorder.

The developmental origins of Notch-driven intrahepatic bile duct disorders

The Notch signaling pathway is an evolutionarily conserved mechanism of cell-cell communication that mediates cellular proliferation, cell fate specification, and maintenance of stem and progenitor cell populations. In the vertebrate liver, an absence of Notch signaling results in failure to form bile ducts, a complex tubular network that radiates throughout the liver, which, in healthy individuals, transports bile from the liver into the bowel. Loss of a functional biliary network through congenital malformations during development results in cholestasis and necessitates liver transplantation. Here, we examine to what extent Notch signaling is necessary throughout embryonic life to initiate the proliferation and specification of biliary cells and concentrate on the animal and human models that have been used to define how perturbations in this signaling pathway result in developmental liver disorders.

Alagille syndrome caused by NOTCH2 mutation presented atypical pathological changes

BACKGROUND

Alagille syndrome (ALGS) is a rare multisystem disorder caused by mutations in the JAG1 or NOTCH2 gene. However NOTCH2 gene mutations were rarely found in the Alagille patients. Little is known about the clinical and pathological profiles about Alagille patients with NOTCH2 mutation.

CASE REPORT

Our case described a 16-year-old female patient manifesting as recurrent jaundice and abnormal liver function from the second week of her birth. She presented a butterfly vertebrae and typical facial features including a prominent forehead, deep-set eyes, a pointed chin, and a straight nose with bulbous tip. Pathogenic heterozygous c.5857 C > T variant in NOTCH2 gene was found. Her liver biopsy featured by a disorder liver structure with cholestasis and fibrosis in portal area, which is different from typical bile duct paucity reported in JAG1 deficient patients.

RESULTS

A diagnosis of ALGS was made. The patient was treated with ursodeoxycholic acid and compound embryonic bovine liver extract tablets and infusion of human serum albumin to improve her clinical and pathological symptoms.

CONCLUSION

Since Alagille patients with NOTCH2 mutations have been rarely reported, our case will highlight the clinical and pathological profiles of these patients.

Alagille syndrome: Oral manifestations-A case report

The Alagille syndrome (AGLS) is a rare condition, with few studies reported in the literature, especially in the field of dentistry. It consists of a disease involving many systemic problems and specific facial features. The liver and heart are the most intensely affected organs, and depending on the severity, it may be necessary to perform transplants. It is an autosomal dominant disease with a variable expressivity, and its prevalence is 1/100,000 live births. Dental findings are conflicting. Some authors claim that dental anomalies occur only in deciduous dentitions; however, there is evidence that permanent teeth can also be affected, as will be described in this paper, through a case report of a patient diagnosed with AGLS, who sought out the Dentistry service at Pontifical Catholic University of Minas Gerais, complaining of a strong stain in her teeth, severe dental crowding, and a facial appearance of prognathism.

Characterization of the Spectrum of Ophthalmic Changes in Patients With Alagille Syndrome

Purpose

The purpose of this study was to characterize the phenotypic spectrum of ophthalmic findings in patients with Alagille syndrome.

Methods

We conducted a retrospective, observational, multicenter, study on 46 eyes of 23 subjects with Alagille syndrome. We reviewed systemic and ophthalmologic data extracted from medical records, color fundus photography, fundus autofluorescence, optical coherence tomography, visual fields, electrophysiological assessments, and molecular genetic findings.

Results

Cardiovascular abnormalities were found in 83% of all cases (of those, 74% had cardiac murmur), whereas 61% had a positive history of hepatobiliary issues, and musculoskeletal anomalies were present in 61% of all patients. Dysmorphic facies were present in 16 patients, with a broad forehead being the most frequent feature. Ocular symptoms were found in 91%, with peripheral vision loss being the most frequent complaint. Median (range) Snellen visual acuity of all eyes was 20/25 (20/20 to hand motion [HM]). Anterior segment abnormalities were present in 74% of the patients; of those, posterior embryotoxon was the most frequent finding. Abnormalities of the optic disc were found in 52%, and peripheral retinal abnormalities were the most frequent ocular finding in this series, found in 96% of all patients. Fifteen JAG1 mutations were identified in 16 individuals; of those, 6 were novel.

Conclusions

This study reports a cohort of patients with Alagille syndrome in which peripheral chorioretinal changes were more frequent than posterior embryotoxon, the most frequent ocular finding according to a number of previous studies. We propose that these peripheral chorioretinal changes are a new hallmark to help diagnose this syndrome.

Neurofibromatosis Type 1 With Cherubism-like Phenotype, Multiple Osteolytic Bone Lesions of Lower Extremities, and Alagille-syndrome: Case Report With Literature Survey

BACKGROUND/AIM

Neurofibromatosis type 1 (NF) is an autosomal dominant hereditary disease. The cardinal clinical findings include characteristic skeletal alterations. Difficulties in diagnosis and therapy can arise if an individual has further illnesses.

CASE REPORT

This is a case report of a 16-year-old patient affected by NF1. She also suffered from Alagille syndrome and the consequences of fetal alcohol exposure. The patient's facial phenotype showed findings that could be assigned to one or more of the known diseases. The patient was referred for treating a cherubism-like recurrent central giant cell granuloma (CGCG) of the jaw. The patient developed bilateral, multilocular non-ossifying fibromas (NOF) of the long bones of the lower extremity. Treatment of the skeletal lesions consisted of local curettage. While NOF regressed after surgery, the CGCG of the jaw remained largely unchanged. Extensive genetic tests confirmed a previously unknown germline mutation in the JAG1 gene, the germline mutation of the NF1 gene, and the somatic mutation in the NF1 gene in the diffuse plexiform neurofibroma, but not in the CGCG.

CONCLUSION

Assigning facial findings to a defined syndrome is ambiguous in many cases and especially difficult in patients who have multiple diseases that can affect the facial phenotype. Surgical therapy should be adapted to the individual findings.

Two Novel Mutations in the JAG1 Gene in Pediatric Patients with Alagille Syndrome: The First Case Series in Czech Republic

Background: Alagille syndrome (ALGS) is a highly variable multisystem disorder inherited in an autosomal dominant pattern with incomplete penetration. The disorder is caused by mutations in the JAG1 gene, only rarely in the NOTCH2 gene, which gives rise to malformations in multiple organs. Bile duct paucity is the main characteristic feature of the disease. Methods: Molecular-genetic examination of genes JAG1 and NOTCH2 in four probands of Czech origin who complied with the diagnostic criteria of ALGS was performed using targeted next-generation sequencing of genes JAG1 and NOTCH2. Segregation of variants in a family was assessed by Sanger sequencing of parental DNA. Results: Mutations in the JAG1 gene were confirmed in all four probands. We identified two novel mutations: c.3189dupG and c.1913delG. Only in one case, the identified JAG1 mutation was de novo. None of the parents carrying JAG1 pathogenic mutation was diagnosed with ALGS. Conclusion: Diagnosis of the ALGS is complicated due to the absence of clear genotype-phenotype correlations and the extreme phenotypic variability in the patients even within the same family. This fact is of particular importance in connection to genetic counselling and prenatal genetic testing.

A form of muscular dystrophy associated with pathogenic variants in JAG2

JAG2 encodes the Notch ligand Jagged2. The conserved Notch signaling pathway contributes to the development and homeostasis of multiple tissues, including skeletal muscle. We studied an international cohort of 23 individuals with genetically unsolved muscular dystrophy from 13 unrelated families. Whole-exome sequencing identified rare homozygous or compound heterozygous JAG2 variants in all 13 families. The identified bi-allelic variants include 10 missense variants that disrupt highly conserved amino acids, a nonsense variant, two frameshift variants, an in-frame deletion, and a microdeletion encompassing JAG2. Onset of muscle weakness occurred from infancy to young adulthood. Serum creatine kinase (CK) levels were normal or mildly elevated. Muscle histology was primarily dystrophic. MRI of the lower extremities revealed a distinct, slightly asymmetric pattern of muscle involvement with cores of preserved and affected muscles in quadriceps and tibialis anterior, in some cases resembling patterns seen in POGLUT1-associated muscular dystrophy. Transcriptome analysis of muscle tissue from two participants suggested misregulation of genes involved in myogenesis, including PAX7. In complementary studies, Jag2 downregulation in murine myoblasts led to downregulation of multiple components of the Notch pathway, including Megf10. Investigations in Drosophila suggested an interaction between Serrate and Drpr, the fly orthologs of JAG1/JAG2 and MEGF10, respectively. In silico analysis predicted that many Jagged2 missense variants are associated with structural changes and protein misfolding. In summary, we describe a muscular dystrophy associated with pathogenic variants in JAG2 and evidence suggests a disease mechanism related to Notch pathway dysfunction.

Long-term follow-up of a patient with JAG1-associated retinopathy

PURPOSE

To report the long-term structural and functional changes in the posterior segments of an adult with an unusual retinal dystrophy caused by a novel mutation in JAG1.

METHODS

A 33-year-old female underwent comprehensive ophthalmic examination, including best corrected visual acuity (BCVA) measurement, dilated fundus imaging (wide-angle fundus colour and short wavelength autofluorescence imaging), macular and peripheral spectral-domain optical coherence tomography (SD-OCT) and electroretinography (ERG) at baseline and 10 years later at the age of 43. The patient also underwent systemic review with detailed cardiac, brain and renal investigations. During follow-up, genetic analysis using whole-exome sequencing was performed on the patient and her parents to identify disease-causing variants.

RESULTS

The patient's main complaint was of a recent onset of bilateral photophobia and blurred vision in the left eye. On examination, the most striking retinal finding was of bilateral well-demarcated, anterior circumferential chorioretinal atrophy with scattered pigment clumping from the mid periphery to the ora. In addition, she had posterior pole RPE hypopigmentation, peripapillary chorioretinal atrophy, left macular choroidal folds and retinal vasculature tortuosity with atypical branching. Her retinal electrophysiology was consistent with a cone rod photoreceptor dystrophy and left macular dysfunction. Ten years later, her BCVA, the anterior circumferential chorioretinal atrophy and her visual field constriction all remained stable. Her retinal electrophysiology demonstrated deterioration of left rod function, while cone dysfunction remained stable. Macular function deteriorated in both eyes. During follow-up, she was also noted to have progressive aortic root dilatation, posterior embryotoxon and an x ray diagnosis of butterfly vertebrae. Whole-exome sequencing revealed a novel c.2412C > A p.(Tyr804Ter) truncating mutation in JAG1 that was predicted to be pathogenic and suggested a diagnosis of Alagille syndrome.

CONCLUSION

This is the first report of the long-term detailed follow-up of a patient with Alagille syndrome whose most striking ophthalmic finding was bilateral well-demarcated, anterior circumferential chorioretinal atrophy. During follow-up, this finding remained stable, suggesting that this may be developmental in origin. This is in contrast with the progressive deterioration in the posterior pole retinal and macular function.

Alagille syndrome and non-syndromic paucity of the intrahepatic bile ducts

The observation of bile duct paucity is an important diagnostic finding in children, occurring in roughly 11% of pediatric liver biopsies. Alagille syndrome (ALGS) is a well-defined syndromic form of intrahepatic bile duct paucity that is accompanied by a number of other key features, including cardiac, facial, ocular, and vertebral abnormalities. In the absence of these additional clinical characteristics, intrahepatic bile duct paucity results in a broad differential diagnosis that requires supplementary testing and characterization. Nearly 30 years after ALGS was first described, genetic studies identified a causative gene, JAGGED1, which spearheaded over two decades of research aimed to meticulously delineate the molecular underpinnings of ALGS. These advancements have characterized ALGS as a genetic disease and led to testing strategies that offer the ability to detect a pathogenic genetic variant in almost 97% of individuals with ALGS. Having a molecular understanding of ALGS has allowed for the development of numerous in vitro and in vivo disease models, which have provided hope and promise for the future generation of gene-based and protein-based therapies. Generation of these disease models has offered scientists a mechanism to study the dynamics of bile duct development and regeneration, and in doing so, produced tools that are applicable to the understanding of other congenital and acquired liver diseases.

Neonatal cholestasis can be the first symptom of McCune–Albright syndrome: A case report

BACKGROUND

McCune–Albright syndrome (MAS) is caused by postzygotic somatic mutations of the GNAS gene. It is characterized by the clinical triad of fibrous dysplasia, café-au-lait skin spots, and endocrinological dysfunction. Myriad complications in MAS, including hepatobiliary manifestations, are also reported.

CASE SUMMARY

This is a case of a 4-year-old boy who presented with MAS with neonatal cholestasis. He was suspected to have Alagille syndrome due to neonatal cholestasis with intrahepatic bile duct paucity in liver biopsy, peripheral pulmonary artery stenosis, and renal tubular dysfunction. By the age of 2 years, his cholestatic liver injury gradually improved, but he had repeated left femoral fractures. He did not exhibit endocrinological abnormality or café-au-lait skin spots. However, MAS was suspected due to fibrous dysplasia at the age of 4 years. No mutation was identified in the GNAS gene in the DNA isolated from the peripheral blood, but an activating point mutation (c.601C>T, p.Arg201Cys) was observed in the DNA extracted from the affected bone tissue and that extracted from the formalin-fixed paraffin-embedded liver tissue, which was obtained at the age of 1 mo.

CONCLUSION

MAS should be considered as a differential diagnosis for transient cholestasis in infancy.