Genetic Variants Of Unknown Significance Research Articles

Sequence variants of unknown significance in small fiber neuropathy : Characterization of a heterogeneous patient population

In almost half of patients suffering from small fiber neuropathies (SFN), the etiology remains elusive. For these patients with "idiopathic SFN", symptomatic analgesic therapy is the only option. Reports on apotential genetic background of neuropathic pain syndromes are increasing and particularly in SFN patients, several genetic variants were found mainly located in genes encoding voltage-gated sodium channels. Although up to 30% of SFN patients show genetic alterations, most of these remain of "unknown pathogenic significance" and little is known about "genetic SFN". The study aimed to determine clinical characteristics of SFN patients carrying arare genetic variant of unknown significance in pain-associated genes. From 2015 to 2020, 66patients with primarily idiopathic SFN were examined and rare gene variants of unknown significance detected in 13/66 (20%) of these. Adetailed medical history with focus on pain was recorded and patients filled in standardized questionnaires to assess physical and emotional burden due to pain. The authors found 13/66 (20%) patients with rare variants of unknown significance located in pain-associated genes who reported pain refractory to analgesic treatment, ahigher number of external factors influencing clinical symptoms, and ahigher level of physical impairment and emotional stress due to pain compared with patients without such genetic variants. Early genetic assessment is recommended to optimize the management of patients with potentially hereditary SFN. Early access to rehabilitation and mental support as well as aconsequent elimination of external triggering factors should be granted.

Pathogenic Gene Variants Identified in Patients Presenting With Perthes or Perthes-like Hip Disorder.

Legg-Calve-Perthes disease (LCPD) is a diagnosis of exclusion. Various conditions, such as skeletal dysplasias, can closely mimic LCPD and these must be ruled out to provide appropriate treatment, prognosis, and counseling. Traditionally, genetic testing has not been readily available in pediatric orthopaedic practice. Furthermore, the clinical value of genetic testing patients with LCPD is unclear. With the advance of next-generation sequencing (NGS) technology, genetic testing has become clinically available as a lab test. The purposes of this study were to assess the clinical utility of genetic testing in select patients with LCPD and to determine the patient characteristics of those who tested positive for skeletal dysplasia. This is an IRB-approved, retrospective study of 63 consecutive patients who presented with Perthes-like symptoms and/or x-ray findings and who had genetic testing. The reason(s) for genetic testing included bilateral hip disease, family history of LCPD, short stature, suspected skeletal dysplasia, atypical radiographic findings, and/or combinations of these reasons. Of the 63 patients, 19 patients (30%) were found to have a pathogenic gene variant. In 8 of the 19, a variety of skeletal dysplasia was diagnosed. The remaining 11 patients were found to be carriers of autosomal recessive disorders. All 19 patients were referred for genetic counseling. Of the 8 patients found to have skeletal dysplasia, 3 had bilateral disease, 3 were <10 percentile in height, 1 had a family history of "LCPD," and 3 had atypical x-ray findings. In addition to the pathogenic variants, numerous genetic variants of unknown significance were found with 2 gene variants showing exactly the same variant found in 2 unrelated patients. With 30% of the patients showing pathogenic results, genetic testing of select patients with Perthes-like disease is valuable in detecting an underlying genetic disorder or a carrier status of a genetic disorder.

Genetic variants of unknown significance in alpha-galactosidase A: Cellular delineation from Fabry disease.

Fabry disease (FD) is an X-linked multiorgan disorder caused by variants in the alpha-galactosidase A gene (GLA). Depending on the variant, disease phenotypes range from benign to life-threatening. More than 1000 GLA variants are known, but a link between genotype and phenotype in FD has not yet been established for all. p.A143T, p.D313Y, and p.S126G are frequent examples of variants of unknown significance (VUS). We have investigated the potential pathogenicity of these VUS combining clinical data with data obtained in human cellular in vitro systems. We have analyzed four different male subject-derived cell types for alpha-galactosidase A enzyme (GLA) activity and intracellular Gb3 load. Additionally, Gb3 load in skin tissue as well as clinical data were studied for correlates of disease manifestations. A reduction of GLA activity was observed in cells carrying p.A143T compared with controls (p < 0.05). In cells carrying the p.D313Y variant, a reduced GLA activity was found only in endothelial cells (p < 0.01) compared with controls. No pathological changes were observed in cells carrying the p.S126G variant. None of the VUS investigated caused intracellular Gb3 accumulation in any cell type. Our data of aberrant GLA activity in cells of p.A143T hemizygotes and overall normal cellular phenotypes in cells of p.D313Y and p.S126G hemizygotes contribute a basic science perspective to the clinically highly relevant discussion on VUS in GLA.

Re-evaluation of Genetic Variants in Parkinson's Disease Using Targeted Panel and Next-Generation Sequencing.

Parkinson's disease (PD) is a complex disorder with a significant genetic component. Genetic variations associated with PD play a crucial role in the disease's inheritance and prognosis. Currently, 31 genes have been linked to PD in the OMIM database, and the number of genes and genetic variations identified is steadily increasing. To establish a robust correlation between phenotype and genotype, it is essential to compare research findings with existing literature. In this study, we aimed to identify genetic variants associated with PD using a targeted gene panel with next-generation sequencing (NGS) technology. Our objective was also to explore the idea of re-analyzing genetic variants of unknown significance (VUS). We screened 18 genes known to be related to PD using NGS in 43 patients who visited our outpatient clinic between 2018-2019. After 12-24 months, we re-evaluated the detected variants. We found 14 different heterozygous variants classified as pathogenic, likely pathogenic, or VUS in 14 individuals from nonconsanguineous families. We re-evaluated 15 variants and found changes in their interpretation. Targeted gene panel analysis with NGS can help identify genetic variants associated with PD with confidence. Re-analyzing certain variants at specific time intervals can be especially beneficial in selected situations. Our study aims to expand the clinical and genetic understanding of PD and emphasizes the importance of re-analysis.

HAP1, a new revolutionary cell model for gene editing using CRISPR-Cas9.

The use of next-generation sequencing (NGS) technologies has been instrumental in the characterization of the mutational landscape of complex human diseases like cancer. But despite the enormous rise in the identification of disease candidate genetic variants, their functionality is yet to be fully elucidated in order to have a clear implication in patient care. Haploid human cell models have become the tool of choice for functional gene studies, since they only contain one copy of the genome and can therefore show the unmasked phenotype of genetic variants. Over the past few years, the human near-haploid cell line HAP1 has widely been consolidated as one of the favorite cell line models for functional genetic studies. Its rapid turnover coupled with the fact that only one allele needs to be modified in order to express the subsequent desired phenotype has made this human cell line a valuable tool for gene editing by CRISPR-Cas9 technologies. This review examines the recent uses of the HAP1 cell line model in functional genetic studies and high-throughput genetic screens using the CRISPR-Cas9 system. It covers its use in an attempt to develop new and relevant disease models to further elucidate gene function, and create new ways to understand the genetic basis of human diseases. We will cover the advantages and potential of the use of CRISPR-Cas9 technology on HAP1 to easily and efficiently study the functional interpretation of gene function and human single-nucleotide genetic variants of unknown significance identified through NGS technologies, and its implications for changes in clinical practice and patient care.

OR05-3 Utility of Genomic work-up for 46XY Disorder of Sex Development Patients with Severe Hypospadias

Abstract Background Hypospadias is a common human congenital anomaly occurring in ∼1: 200 to 1: 300 live male births in the USA, with an unexplained doubling in incidence over previous decades. Historically, 46XY Differences of Sex Development (DSD) patients, with severe hypospadias have lacked a genetic diagnosis. With the advent of commercially available DSD genomic panels, this is now changing (GeneDX. Neonatal 46 2021, In-vitae 2021). The goal of this study is to review the anatomical characteristics of severe hypospadias that can accurately define patients that have 46XY DSD and to determine the practical utility of performing a genomic workup in these rare 46XY DSD patients with severe hypospadias.Patients: 14 patients seen in disorders of sexual development clinic between 2018–2020 with severe hypospadias defined by an ectopic urethral meatus typically in the scrotum or perineum, an abnormally small glans penis size (&amp;lt;14 mm at maximal width in the first year of life), severe curvature and associated foreskin fusion or penoscrotal transposition were enrolled in the study. Methods Patients who met the criteria for 46XY disorder of sexual development and severe hypospadias were offered a genomic work-up in consultation with pediatric genetics. Patients were identified through chart review. Data extracted included karyotype, hypospadias phenotype including stretched penile length at diagnosis, age at genetic diagnosis/genomic workup, gene defect/ pathologic variant, gender identity, and clinical course.Main Outcome Measurements: The main outcome measured was the presence of a genetic mutation that can be linked to the disorder of sexual development. Secondary outcomes measured included gender identity, clinical course, and histological findings if a biopsy was obtained. Results Of the 14 patients that underwent genomic analysis, 8 had documented pathologic variants known to cause hypospadias. Pathologic genetic variants include defects in the AR (3), SRD5A2 (1), NR5A1 (2), WT1 (1), and ARTX (1). Five had no evidence of pathologic variants based on the Invitae and GeneDx commercial 46XY DSD panel (see Table 2 for genes tested). One had a genetic variant of unknown significance, FREM2. The patient with WT1 was consequently found to have a Wilms tumor and the patients with SRD5A2 are now undergoing adrenal insufficiency surveillance after their genetic testing. Conclusions Patients with 46XY DSD and severe hypospadias can benefit from genetic evaluation as their underlying disorders may unveil mutations that could have potentially life-altering consequences and change surveillance and monitoring. Presentation: Saturday, June 11, 2022 12:00 p.m. - 12:15 p.m.

RF21 | PSUN07 Germline Genetic Testing in a Cohort of Adults with Adrenocortical Carcinoma : Insights From a Clinical Care Setting

Abstract Context About 5-10% of adrenocortical cancer (ACC) arise in patients with genetic predisposition syndromes, including Li-Fraumeni, Lynch, MEN1, or Familial Adenomatous Polyposis (APC). Recent European (2018) and American guidelines (2020) recommend that all adults with ACC should be offered clinical genetic counseling. There is a paucity of data regarding systematic germline testing in adults with ACC and the extent of the genetic evaluation is unclear. Objective To describe the germline genetic characteristics in a cohort of adult patients with ACC evaluated in a tertiary clinical care center. Methods Data including demographics, personal and family history of neoplasia, pathology reports, clinical features and genetic testing were retrospectively collected from charts of patients treated at Centre hospitalier de l'Université de Montréal (CHUM). After genetic counseling, genetic testing was proposed to patients with a pathologic diagnosis of ACC. From 2005 to 2015, TP53 gene analysis was performed using direct sequencing and MLPA. Since 2016, multigene testing was performed for a progressively increasing number of oncogenic genes using a custom next-generation panel for germline leucocyte DNA including at least the TP53, MSH2, MSH6, MLH1,PMS2, EPCAM, MEN1, BRCA1 and BRCA2 genes (Invitae, CA). An extended panel, based on past medical and familial history, was performed at the discretion of the geneticist. Patient data was retrospectively investigated. Results We analyzed data from 44 patients with available germline genetic results. Median age of the patients was 46 years (ranging from 22 to 79 years), including 11 males (25.0%) and 33 females (75.0%). Ten patients (22.7%) underwent only TP53 gene analysis and 32 patients (72.7%) were studied using the larger oncogenic genetic panel. Germline pathogenic or likely pathogenic variants were identified in 5 of the 44 patients (11.4%) while genetic variants of unknown significance (VUS) were found in 7 of the 44 patients (15.9%). Among patients with pathogenic variants, one had a family history and known germline mutation in the BRCA2 gene (8765delAG, p.Glu2846GlyfsX23). One patient had a personal and familial medical history suggesting a MEN1 syndrome that was confirmed with the finding of a germline MEN1 mutation (c.1556delC, p.Pro519Leu fs40). Unsuspected germline pathogenic variants were found in three patients: 1) TP53 (c.425delC, p.Pro142fs), 2) MUTYH (c.536A&amp;gt;G, p.Tyr179Cys) and 3) MSH6 (c.3649-3655, p.Arg1217Leu fs9) genes. Variants of unknown significance (VUS) were found in the following genes: POT1, MSH3, PALB2, RAD51d, APC, ATM and BRCA2. Conclusions Germline pathogenic variants were found in 11.4% of our cohort of patients with ACC. VUS were found in 15.9% of patients but their significance remains to be determined. Genetic counseling and germline genetic testing should be offered to all patients with ACC; however the optimal use and extent of oncogenic gene panels need to be better defined. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m., Sunday, June 12, 2022 12:48 p.m. - 12:53 p.m.

Niemann-Pick type C disease as proof-of-concept for intelligent biomarker panel selection in neurometabolic disorders.

Using Niemann-Pick type C disease (NPC) as a paradigm, we aimed to improve biomarker discovery in patients with neurometabolic disorders. Using a multiplexed liquid chromatography tandem mass spectrometry dried bloodspot assay, we developed a selective intelligent biomarker panel to monitor known biomarkers N-palmitoyl-O-phosphocholineserine and 3β,5α,6β-trihydroxy-cholanoyl-glycine as well as compounds predicted to be affected in NPC pathology. We applied this panel to a clinically relevant paediatric patient cohort (n=75; 35 males, 40 females; mean age 7 years 6 months, range 4 days-19 years 8 months) presenting with neurodevelopmental and/or neurodegenerative pathology, similar to that observed in NPC. The panel had a far superior performance compared with individual biomarkers. Namely, NPC-related established biomarkers used individually had 91% to 97% specificity but the combined panel had 100% specificity. Moreover, multivariate analysis revealed long-chain isoforms of glucosylceramide were elevated and very specific for patients with NPC. Despite advancements in next-generation sequencing and precision medicine, neurological non-enzymatic disorders remain difficult to diagnose and lack robust biomarkers or routine functional testing for genetic variants of unknown significance. Biomarker panels may have better diagnostic accuracy than individual biomarkers in neurometabolic disorders, hence they can facilitate more prompt disease identification and implementation of emerging targeted, disease-specific therapies. Intelligent biomarker panel design can help expedite diagnosis in neurometabolic disorders. In Niemann-Pick type C disease, such a panel performed better than individual biomarkers. Biomarker panels are easy to implement and widely applicable to neurometabolic conditions.

Ornithine transcarbamylase deficiency: A diagnostic odyssey

Ornithine transcarbamylase deficiency: A diagnostic odyssey

Pathogenicity Reclassification of Genetic Variants Related to Early-Onset Breast Cancer among Women of Mongoloid Origin.

Background:Germline alterations in BRCA1, BRCA2, and other genes are responsible for early-onset breast cancer. However, up to 20% of molecular tests report genetic variant of unknown significance (VUS) or novel variants that have never been previously described and their clinical significance are unknown. This study aimed to reclassify variant of unknown significance (VUS) or novel variants by using the ActiveDriveDB database that annotates variants through the lens of sites of post-translational modifications (PTM). Methods:Our study included thirty-eighth young Buryat BC patients, belonging to the Mongoloid race and anthropologically to the Central Asia. Genomic DNA was extracted from the peripheral blood lymphocytes using the phenol/chloroform method. DNA library were prepared using the Hereditary Cancer SolutionTM kit (Sophia GENETICS, Switzerland) to cover 27 genes, such as ATM, APC, BARD1, BRCA1, BRCA2, BRIP1, CDH1, CHEK2, EPCAM, FAM175A, MLH1, MRE11A, MSH2, MSH6, MUTYH, NBN, PALB2, PIK3CA, PMS2, PMS2CL, PTEN, RAD50, RAD51C, RAD51D, STK11, TP53, and XRCC2. Paired-end sequencing (2 x 150 bp) was conducted using NextSeq 500 system (Illumina, USA). Results:We re-examined 135 rare variants (41 VUS, 25 conflicting, 64 benign and 5 new variants). We identified 10 out of 135 (7.4%) mutations that affected the sites of post-translational modification in proteins. Of 135 rare mutations, 1 benign variant was reclassified as network-rewiring - motif loss mutation, 3 VUS and 1 new variant were reclassified as distal PTM- mutations, 2 new and 1 benign variant were classified as proximal PTM- mutations and 1 benign and 1 conflicting variant were classified as direct PTM- mutations.Conclusions:For the first time, 7.4% (10 out of 135) of mutations that affected the sites of post-translational modification in proteins were identified among early-onset breast cancer women of Mongoloid origin.

Hereditary neuropathies: Genetics and utility of nerve biopsy.

Peripheral neuropathy is one of the most common neurological conditions of the nervous system. Hereditary neuropathies (HNs) form an important group with varying degrees of severity, causing a significant disease burden. Accurate diagnosis is essential for management, counseling, and preventing unnecessary extended workups for acquired etiologies and inappropriate treatment. Several hereditary neuropathies have characteristic or diagnostic histologic findings; however, in the era of molecular diagnostics, the role of nerve biopsy in the diagnosis of hereditary neuropathy has reduced significantly. Nevertheless, in sporadic cases, cases without a clear family history, clinical mimics, cases with rare mutations, and genetic variants of unknown significance, a nerve biopsy can confirm the diagnosis, provide an unexpected diagnosis, or direct a targeted molecular testing. HN may be non-syndromic, affecting predominantly the peripheral nervous system or syndromic where it is a part of more widespread neurological or multisystem involvement. This review summarizes the microscopic pathological features in a nerve biopsy in some of the more commonly encountered inherited peripheral neuropathies highlighting their utility in selected cases.

Abstract P2-09-06: Increased rates of genetic variants of unknown significance in Latino and African American populations of south Texas

Abstract Hereditary susceptibility studies for breast cancer are key to enhancing early detection and exercising prevention strategies in order to reduce breast cancer mortality. Germline pathogenic variants that have shown susceptibility to breast and ovarian cancer are detected in gene panels including ATM, BRCA1, BRCA2, BRIP1, CDH1, CDKN2A, CHEK2, DICER1, EPCAM, MLH1, MSH2, MSH6, NBN, NF1, PALB2, PMS2, PTEN, POLE, RAD50, RAD51C, RAD51D, RECQL, STK11, and TP53. Historically, minority populations have been overlooked both in reach and access to genetic testing, resulting in a lack of knowledge of the genomic landscape and creating a barrier to the application of genetics in clinical medicine. This is the case with the populations of South Texas including the Texas-Mexico border region. According to the US Census Bureau, the South Texas region population is comprised of 69% Hispanics while the Texas-Mexico border region population is comprised of over 90% Hispanics. Previous studies have shown multiple pathogenic variants and also variants of unknown significance (VUS) specific to ethnic populations and regions, but there is little information regarding the Mexican American population of South Texas.Our GRACIAS Texas Program has provided services to individuals and professionals across 26 counties in the South Texas area by specifically providing cancer genetic counseling and testing to individuals and families at highest risk. Recruitment was accomplished through comprehensive outreach to communities through health fairs, small group education sessions, mammography centers, hospitals, FQHCs, and direct interactions with medical providers. Although our program focused on recognizing both breast and colon cancer, and also reached those with rare cancer predisposition syndromes, the concern for breast cancer risk was most commonly addressed, accounting for the majority of cases. A total of 1595 individuals were identified as appropriate for cancer genetic counseling, and of these, 1377 individuals completed genetic testing. Of all individuals who received cancer genetic counseling, 1269 (79.5%) were Hispanic, 16% non-Hispanic White, 3% African American, and 1% other race/ethnicity. The group of individuals receiving testing consisted of 86% females and 14% males. Of those tested, 259 (18.8%) individuals were found to have pathogenic genetic variant and 187 (13.7%) individuals were found to have a VUS. Notedly, the VUS were nearly twice as common in the Hispanic population (14%) as compared to non-Hispanic White population (7.2%). This underscores the disparities of knowledge in genomic variation in Hispanic and non-Hispanic population. We also note that although the percentage of African American patients seen was small, 12 of 45 (26.6%) were found to have a VUS which further reflects the underrepresentation of African Americans in genomic landscape studies.These variants are important because they present a dilemma when advising patients as to need for cancer screening. However, recognition and further exploration of these VUS provide a future pathway to functional assessment and thus eventual knowledge to guide patient care. We continue to monitor for any changes to the status of these VUS. Although many variants are ultimately classified as benign variations, we have seen cases in which a VUS is reclassified into a likely pathogenic or definitely pathogenic variation having significant implications for screening, prevention, and management for these individuals and their families emphasizing further the need to continue to follow individuals tested. Our observations will help define the gene-specific risks of individuals and families in our underserved communities and will support the goal of closing gaps in genomic disparities.Supported by CPRIT grants PP120089 and PP160011 and NIH P30 CA54174. Citation Format: Stephanie Soewito, Rachel Wyatt, Emily Berenson, Natalie Poullard, Shawn Gessay, Lindsey Mette, Kristin Shelby, Elise Alvarez, Clarissa Aviles, Anna Maria Pulido Saldivar, Pamela Otto, Ismail Jatoi, Virginia Kaklamani, Gail E Tomlinson. Increased rates of genetic variants of unknown significance in Latino and African American populations of south Texas [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-09-06.

New mutation of the TP53 gene associated with the hereditary breast cancer in a young Tuvinian woman

Background. The identification of the ethnospecific mutations associated with hereditary breast cancer remains challenging. Next generation sequencing (Ngs) technology fully enables the compilation of germline variants associated with the risk for inherited diseases. Despite the success of the Ngs, up to 20 % of molecular tests report genetic variant of unknown significance (Vus) or novel variants that have never been previously described and their clinical significances are unknown. To obtain extended information about the variants of the unknown significance, it is necessary to use an alternative approach for the analysis of the Ngs data. To obtain extended characteristic about the unknown significance variants, it is necessary to search for additional tools for the analysis of the Ngs data. Material and methods. We reclassified the mutation of the unknown significance using the activedrivedb database that assessed the effect of mutations on sites of post-translational modifications, and the proteinpaint tool that complemented the existing cancer genome portals and provided a comprehensive and intuitive view of cancer genomic data. Results. In this study, we report a 44-year-old tuvinian woman with a family history of breast cancer. Based on the Ngs data, mutational analysis revealed the presence of the lrg_321t1: c.80c&gt;t heterozygous variant in exon 2, which led to the proline to leucine change at codon 27 of the protein. In the dbpubmed database, this mutation was determined as unknown significance due to data limitation. According to the data of the activedriverdb tool, this mutation is located distally at the site of post-translational protein modification, which is responsible for binding to kinases that regulate genes of the cell cycle, etc. (atm, chek2, cdk, mapk). In accordance with proteinpaint tool, the lrg_321t1: c.80c&gt;t mutation is located in functionally specialized transactivation domains and codon of the tp53 gene, where the pathogenic mutation associated with li-Fraumeni syndrome has been earlier described. Conclusion. This report is the first to describe a new variant in the tp53 gene (rs1555526933), which is likely to be associated with hereditary cancer-predisposing syndrome, including li-Fraumeni syndrome, in a tuvinian Bc patient with young-onset and familial Bc.

High risk population screening for Fabry disease in hemodialysis patients in Vojvodina: Pilot study

Introduction/Objective. Fabry disease (FD) is an X-linked lysosomal storage disease that develops as a consequence of mutation in the alpha-galactosidase A (GLA) gene. There are more than 1080 known variants in the GLA gene. Some of them are pathogenic, but most of them are benign or represent the genetic change that can be classified as a genetic variant of unknown significance or simply be a representation of genetic polymorphism. There are two main features of FD, classic form and late-onset variants of disease. The main target organs in patients with FD are the kidneys, heart, and nervous system. Bearing in mind the fact that FD is a rare disease, the best way for active searching of patients is high-risk population screening, after which family screening for every proband case should be performed. Methods. In this paper, we present results of a multicentric pilot study that represents findings from the screening of hemodialysis patients for FD in six hemodialysis units in Vojvodina. Results. We have found one patient with benign mutation and 16 patients with genetic polymorphisms in GLA gene. We have learned that genetic changes in GLA gene can be frequent, but very rarely are of clinical significance and lead to manifestations of FD. Conclusion. Results of this screening study will give us important insights into our future work.

Induced Pluripotent Stem Cells From Subjects With Primary Sclerosing Cholangitis Develop a Senescence Phenotype Following Biliary Differentiation.

Primary sclerosing cholangitis (PSC) is a chronic fibroinflammatory disease of the biliary tract characterized by cellular senescence and periportal fibrogenesis. Specific disease features that are cell intrinsic and either genetically or epigenetically mediated remain unclear due in part to a lack of appropriate, patient‐specific, in vitro models. Recently, our group developed systems to create induced pluripotent stem cell (iPSC)‐derived cholangiocytes (iDCs) and biliary epithelial organoids (cholangioids). We use these models to investigate whether PSC cholangiocytes are intrinsically predisposed to cellular senescence. Skin fibroblasts from healthy controls and subjects with PSC were reprogrammed to pluripotency, differentiated to cholangiocytes, and subsequently grown in three‐dimensional matrigel‐based culture to induce formation of cholangioids. RNA sequencing (RNA‐seq) on iDCs showed significant differences in gene expression patterns, including enrichment of pathways associated with cell cycle, senescence, and hepatic fibrosis, that correlate with PSC. These pathways also overlapped with RNA‐seq analysis on isolated cholangiocytes from subjects with PSC. Exome sequencing on the subjects with PSC revealed genetic variants of unknown significance in the genes identified in these pathways. Three‐dimensional culture revealed smaller size, lack of a central lumen, and increased cellular senescence in PSC‐derived cholangioids. Congruent with this, PSC‐derived iDCs showed increased secretion of the extracellular matrix molecule fibronectin as well as the inflammatory cytokines interleukin‐6, and chemokine (C‐C motif) ligand 2. Conditioned media (CM) from PSC‐derived iDCs more potently activated hepatic stellate cells compared to control CM. Conclusion: We demonstrated efficient generation of iDCs and cholangioids from patients with PSC that show disease‐specific features. PSC cholangiocytes are intrinsically predisposed to cellular senescence. These features are unmasked following biliary differentiation of pluripotent stem cells and have functional consequences in epithelial organoids.

What Have We Learned from Molecular Biology of Paragangliomas and Pheochromocytomas?

Recent advances in molecular genetics and genomics have led to increased understanding of the aetiopathogenesis of pheochromocytomas and paragangliomas (PPGLs). Thus, pan-genomic studies now provide a comprehensive integrated genomic analysis of PPGLs into distinct molecularly defined subtypes concordant with tumour genotypes. In addition, new embryological discoveries have refined the concept of how normal paraganglia develop, potentially establishing a developmental basis for genotype-phenotype correlations for PPGLs. The challenge for modern pathology is to translate these scientific discoveries into routine practice, which will be based largely on histopathology for the foreseeable future. Here, we review recent progress concerning the cell of origin and molecular pathogenesis of PPGLs, including pathogenetic mechanisms, genetic susceptibility and molecular classification. The current roles and tools of pathologists are considered from a histopathological perspective, including differential diagnoses, genotype-phenotype correlations and the use of immunohistochemistry in identifying hereditary predisposition and validating genetic variants of unknown significance. Current and potential molecular prognosticators are also presented with the hope that predictive molecular biomarkers will be integrated into risk stratification scoring systems to assess the metastatic potential of these intriguing neoplasms and identify potential drug targets.

Hereditary Hypertrophic Cardiomyopathy in Children and Young Adults-The Value of Reevaluating and Expanding Gene Panel Analyses.

Introduction: Sudden cardiac death (SCD) and early onset cardiomyopathy (CM) in the young will always lead to suspicion of an underlying genetic disorder. Incited by the rapid advances in genetic testing for disease we have revisited families, which previously tested “gene-negative” for familial predominantly pediatric CM, in hopes of finding a causative gene variant. Methods: 10 different families with non-syndromic pediatric CM or hypertrophic cardiomyopathy (HCM) with severe disease progression and/or heredity for HCM/CM related SCD with “gene-negative” results were included. The index patient underwent genetic testing with a recently updated gene panel for CM and SCD. In case of failure to detect a pathogenic variant in a relevant gene, the index patient and both parents underwent clinical (i.e., partial) exome sequencing (trio-exome) in order to catch pathogenic variants linked to the disease in genes that were not included in the CM panel. Results: The mean age at clinical presentation of the 10 index cases was 12.5 years (boys 13.4 years, n = 8; girls 9 years, n = 2) and the family history burden was 33 HCM/CM cases including 9 HCM-related SCD and one heart transplantation. In 5 (50%) families we identified a genetic variant classified as pathogenic or likely pathogenic, in accordance with the American College of Medical Genetics and Genomics (ACMG) criteria, in MYH7 (n = 2), RBM20, ALPK3, and PGM1, respectively, and genetic variants of unknown significance (VUS) segregating with the disease in an additional 3 (30%) families, in MYBPC3, ABCC9, and FLNC, respectively. Conclusion: Our results show the importance of renewed thorough clinical assessment and the necessity to challenge previous genetic test results with more comprehensive updated gene panels or exome sequencing if the initial test failed to identify a causative gene for early onset CM or SCD in children. In pediatric cardiomyopathy cases when the gene panel still fails to detect a causative variant, a trio exome sequencing strategy might resolve some unexplained cases, especially if a multisystemic condition is clinically missed.

The Postmortem Interpretation of Cardiac Genetic Variants of Unknown Significance in Sudden Death in the Young: A Case Report and Review of the Literature.

Sudden cardiac death (SCD) in adolescents and young adults is a major traumatic event for families and communities. In these cases, it is not uncommon to have a negative autopsy with structurally and histologically normal heart. Such SCD cases are generally attributed to channelopathies, which include long QT syndrome, short QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia. Our understanding of the causes for SCDs has changed significantly with the advancements in molecular and genetic studies, where many mutations are now known to be associated with certain channelopathies. Postmortem analysis provides great value in informing decision-making with regard to screening tests and prophylactic measures that should be taken to prevent sudden death in first degree relatives of the decedent. As this is a rapidly advancing field, our ability to identify genetic mutations has surpassed our ability to interpret them. This led to a unique challenge in genetic testing called variants of unknown significance (VUS). VUSs present a diagnostic dilemma and uncertainty for clinicians and patients with regard to next steps. Caution should be exercised when interpreting VUSs since misinterpretation can result in mismanagement of patients and their families. A case of a young adult man with drowning as his proximate cause of death is presented in circumstances where cardiac genetic testing was indicated and undertaken. Eight VUSs in genes implicated in inheritable cardiac dysfunction were identified and the interpretation of VUSs in this scenario is discussed.

Two novel variants in the SLC4A3 gene in two families with Short QT Syndrome: the role of cascade screening

Abstract Background Short QT syndrome (SQTS) is a rare, autosomal dominant disease causing sudden cardiac death (SCD). Genetic testing is recommended according to current guidelines. Variants in KCNQ1, KCNH2, KCNJ2 and SLC4A3 genes have been reported in SQTS. Purpose We report implications of genetic testing and cascade screening (CS) in two families with phenotypical presentation of SQTS and novel genetic variants of unknown significance. Methods We performed a thorough clinical and electrophysiological work-up of the index patients of both families. In addition, genetic screening was conducted. Subsequently, segregation analysis of potentially pathogenic variants was carried out in available relatives. Results Index patient 1 presented with a history of recurrent syncope. His ECG showed a shortened QTc of 340ms. Family history was unremarkable. Structural heart disease was excluded by cardiac MRI and coronary angiography. Genetic testing detected a rare heterozygous missense variant in the KCNH2 gene (p.(Arg328Cys), frequency 0.053%), predicted to be pathogenic according to various prediction algorithms (Polyphen, SIFT, Align GVGD, mutation taster). CS of relatives did not confirm this variant as the causative mutation. Reanalysis of whole-exome sequencing data revealed a novel heterozygous missense variant, p.(Arg370Cys) in the recently identified SLC4A3 gene. A variant at the same position has previously been associated with SQTS. CS suggested disease association. The second index patient had a SCD at the age of 17. A previously registered ECG showed a shortened QTc of 340ms. Autopsy revealed no structural heart disease. Post-mortem genetic testing revealed variants in the LDB3, MYH7 and a novel heterozygous missense variant, p.(Ser1039Arg) also in the SLC4A3 gene. Family history was positive for SCD in three 2° relatives. The index patient's father had a positive phenotype with a QTc of 365ms. CS again suggested disease association of the variant in the SLC4A3 gene only. Conclusion Genetic testing revealed two novel variants in the SLC4A3 gene, which was recently implicated in the pathogenesis of the SQTS. Predictive bioinformatic algorithms to assess the pathogenicity of missense variants are of limited relevance, but genetic analysis of additional unaffected and affected family members may be instrumental to identify pathogenic DNA sequence variations. Family tree index patients 1 and 2 Funding Acknowledgement Type of funding source: None

The use of anakinra in the treatment of secondary hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) can be familial or secondary, which is often triggered by infection or malignancy. HLH therapy includes dexamethasone and etoposide. However, therapy is associated with significant morbidity and mortality. Anakinra, a recombinant interleukin-1 receptor antagonist, has been reported to treat macrophage activation syndrome (MAS), rheumatic sHLH. We report our experience with anakinra to treat patients with nonrheumatic secondary HLH (sHLH). Six children were diagnosed with HLH from December 2014 to August 2016 and were treated with subcutaneous anakinra (6-10mg/kg/day divided over four doses) with or without dexamethasone (10mg/m2 /day). Therapy was either escalated or weaned based on clinical and laboratory response. Five of six patients were treated with anakinra and dexamethasone, and one with anakinra alone due to active cytomegalovirus (CMV) pneumonitis. The median age of diagnosis was 1.8years (range 0.8-14.9years). No pathogenic mutations associated with HLH were identified, but three of six possessed genetic variants of unknown significance. Infectious triggers were identified for four patients and two patients had malignancies. The average treatment duration was 8weeks with 3.5-5.5years of follow up. No patient needed escalation of therapy to include etoposide. All patients achieved remission. Anakinra was well tolerated without significant adverse effects. Initial treatment with anakinra (with or without dexamethasone) is a feasible treatment alternative for patients with secondary HLH and may allow for avoidance of etoposide. We recommend early initiation of anakinra when HLH is suspected. A broader investigation of the use of anakinra as a first-line agent for HLH is ongoing.