1
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Wojcik MH, Reuter CM, Marwaha S, Mahmoud M, Duyzend MH, Barseghyan H, Yuan B, Boone PM, Groopman EE, Délot EC, Jain D, Sanchis-Juan A, Starita LM, Talkowski M, Montgomery SB, Bamshad MJ, Chong JX, Wheeler MT, Berger SI, O'Donnell-Luria A, Sedlazeck FJ, Miller DE. Beyond the exome: What's next in diagnostic testing for Mendelian conditions. Am J Hum Genet 2023; 110:1229-1248. [PMID: 37541186 PMCID: PMC10432150 DOI: 10.1016/j.ajhg.2023.06.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 06/13/2023] [Accepted: 06/14/2023] [Indexed: 08/06/2023] Open
Abstract
Despite advances in clinical genetic testing, including the introduction of exome sequencing (ES), more than 50% of individuals with a suspected Mendelian condition lack a precise molecular diagnosis. Clinical evaluation is increasingly undertaken by specialists outside of clinical genetics, often occurring in a tiered fashion and typically ending after ES. The current diagnostic rate reflects multiple factors, including technical limitations, incomplete understanding of variant pathogenicity, missing genotype-phenotype associations, complex gene-environment interactions, and reporting differences between clinical labs. Maintaining a clear understanding of the rapidly evolving landscape of diagnostic tests beyond ES, and their limitations, presents a challenge for non-genetics professionals. Newer tests, such as short-read genome or RNA sequencing, can be challenging to order, and emerging technologies, such as optical genome mapping and long-read DNA sequencing, are not available clinically. Furthermore, there is no clear guidance on the next best steps after inconclusive evaluation. Here, we review why a clinical genetic evaluation may be negative, discuss questions to be asked in this setting, and provide a framework for further investigation, including the advantages and disadvantages of new approaches that are nascent in the clinical sphere. We present a guide for the next best steps after inconclusive molecular testing based upon phenotype and prior evaluation, including when to consider referral to research consortia focused on elucidating the underlying cause of rare unsolved genetic disorders.
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Affiliation(s)
- Monica H Wojcik
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Division of Newborn Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Chloe M Reuter
- Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Shruti Marwaha
- Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Medhat Mahmoud
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Michael H Duyzend
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Hayk Barseghyan
- Center for Genetics Medicine Research, Children's National Research Institute, Children's National Hospital, Washington, DC 20010, USA; Department of Genomics and Precision Medicine, School of Medicine and Health Sciences, George Washington University, Washington, DC 20037, USA
| | - Bo Yuan
- Department of Molecular and Human Genetics and Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Philip M Boone
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Emily E Groopman
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Emmanuèle C Délot
- Department of Genomics and Precision Medicine, School of Medicine and Health Sciences, George Washington University, Washington, DC 20037, USA; Center for Genetics Medicine Research, Children's National Research and Innovation Campus, Washington, DC, USA; Department of Pediatrics, George Washington University, School of Medicine and Health Sciences, George Washington University, Washington, DC 20037, USA
| | - Deepti Jain
- Department of Biostatistics, School of Public Health, University of Washington, Seattle, WA 98195, USA
| | - Alba Sanchis-Juan
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Lea M Starita
- Brotman Baty Institute for Precision Medicine, University of Washington, Seattle, WA 98195, USA; Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Michael Talkowski
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Stephen B Montgomery
- Department of Biomedical Data Science, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Michael J Bamshad
- Brotman Baty Institute for Precision Medicine, University of Washington, Seattle, WA 98195, USA; Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA; Department of Pediatrics, Division of Genetic Medicine, University of Washington, Seattle, WA 98195, USA
| | - Jessica X Chong
- Brotman Baty Institute for Precision Medicine, University of Washington, Seattle, WA 98195, USA; Department of Pediatrics, Division of Genetic Medicine, University of Washington, Seattle, WA 98195, USA
| | - Matthew T Wheeler
- Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Seth I Berger
- Center for Genetics Medicine Research and Rare Disease Institute, Children's National Hospital, Washington, DC 20010, USA
| | - Anne O'Donnell-Luria
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Fritz J Sedlazeck
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Department of Computer Science, Rice University, 6100 Main Street, Houston, TX 77005, USA
| | - Danny E Miller
- Brotman Baty Institute for Precision Medicine, University of Washington, Seattle, WA 98195, USA; Department of Pediatrics, Division of Genetic Medicine, University of Washington, Seattle, WA 98195, USA; Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA.
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2
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Halma J, Lin HC. Alagille syndrome: understanding the genotype-phenotype relationship and its potential therapeutic impact. Expert Rev Gastroenterol Hepatol 2023; 17:883-892. [PMID: 37668532 DOI: 10.1080/17474124.2023.2255518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 09/01/2023] [Indexed: 09/06/2023]
Abstract
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.
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Affiliation(s)
- Jennifer Halma
- Division of Gastroenterology, Department of Pediatrics, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Henry C Lin
- Division of Pediatric Gastroenterology, Department of Pediatrics, Oregon Health & Science University, Portland, OR, USA
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3
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Shen W, Sellers HL, Choate LA, Stein MI, Tandale PP, Tan J, Setlem R, Sakai Y, Fadra N, Sosa C, McClelland SP, Barnett SS, Rasmussen KJ, Runke CK, Smoley SA, Tillmans LS, Marcou CA, Rowsey RA, Thorland EC, Boczek NJ, Kearney HM. Clinical Validation of Tagmentation-Based Genome Sequencing for Germline Disorders. J Mol Diagn 2023; 25:524-531. [PMID: 37088140 DOI: 10.1016/j.jmoldx.2023.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/09/2023] [Accepted: 04/04/2023] [Indexed: 04/25/2023] Open
Abstract
Genome sequencing (GS) is a powerful clinical tool used for the comprehensive diagnosis of germline disorders. GS library preparation typically involves mechanical DNA fragmentation, end repair, and bead-based library size selection followed by adapter ligation, which can require a large amount of input genomic DNA. Tagmentation using bead-linked transposomes can simplify the library preparation process and reduce the DNA input requirement. Here we describe the clinical validation of tagmentation-based PCR-free GS as a clinical test for rare germline disorders. Compared with the Genome-in-a-Bottle Consortium benchmark variant sets, GS had a recall >99.7% and a precision of 99.8% for single nucleotide variants and small insertion-deletions. GS also exhibited 100% sensitivity for clinically reported sequence variants and the copy number variants examined. Furthermore, GS detected mitochondrial sequence variants above 5% heteroplasmy and showed reliable detection of disease-relevant repeat expansions and SMN1 homozygous loss. Our results indicate that while lowering DNA input requirements and reducing library preparation time, GS enables uniform coverage across the genome as well as robust detection of various types of genetic alterations. With the advantage of comprehensive profiling of multiple types of genetic alterations, GS is positioned as an ideal first-tier diagnostic test for germline disorders.
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Affiliation(s)
- Wei Shen
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota.
| | - Heidi L Sellers
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Lauren A Choate
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Mariam I Stein
- Division of Computational Biology, Mayo Clinic Department of Quantitative Health Sciences, Mayo Clinic, Rochester, Minnesota
| | - Pratyush P Tandale
- Division of Computational Biology, Mayo Clinic Department of Quantitative Health Sciences, Mayo Clinic, Rochester, Minnesota
| | - Jiayu Tan
- Division of Computational Biology, Mayo Clinic Department of Quantitative Health Sciences, Mayo Clinic, Rochester, Minnesota
| | - Rohit Setlem
- Division of Computational Biology, Mayo Clinic Department of Quantitative Health Sciences, Mayo Clinic, Rochester, Minnesota
| | - Yuta Sakai
- Division of Computational Biology, Mayo Clinic Department of Quantitative Health Sciences, Mayo Clinic, Rochester, Minnesota
| | - Numrah Fadra
- Division of Computational Biology, Mayo Clinic Department of Quantitative Health Sciences, Mayo Clinic, Rochester, Minnesota
| | - Carlos Sosa
- Division of Computational Biology, Mayo Clinic Department of Quantitative Health Sciences, Mayo Clinic, Rochester, Minnesota
| | - Shawn P McClelland
- Division of Computational Biology, Mayo Clinic Department of Quantitative Health Sciences, Mayo Clinic, Rochester, Minnesota
| | - Sarah S Barnett
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Kristen J Rasmussen
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Cassandra K Runke
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Stephanie A Smoley
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Lori S Tillmans
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Cherisse A Marcou
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Ross A Rowsey
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Erik C Thorland
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Nicole J Boczek
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Hutton M Kearney
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota.
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Funayama M, Nishioka K, Li Y, Hattori N. Molecular genetics of Parkinson's disease: Contributions and global trends. J Hum Genet 2023; 68:125-130. [PMID: 35821405 PMCID: PMC9968657 DOI: 10.1038/s10038-022-01058-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 05/31/2022] [Accepted: 06/20/2022] [Indexed: 01/01/2023]
Abstract
Parkinson's disease (PD) is a neurodegenerative disorder primarily characterized by motor dysfunction. Aging is the greatest risk factor for developing PD. Recent molecular genetic studies have revealed that genetic factors, in addition to aging and environmental factors, play an important role in the development of the disorder. Studies of familial PD have identified approximately 20 different causative genes. PRKN is the most frequently detected causative gene in Japan. The PRKN gene is located at a common fragile site, and both copy number variants as well as single nucleotide variants are frequently detected. The location and variety of variant types makes an accurate genetic diagnosis difficult with conventional genetic testing. In sporadic PD, genome-wide association studies have revealed more than 200 genes that are potential drivers for the development of PD. Many of these studies have been conducted in Caucasian populations alone, which has limited the identification of all genetic risk factors for sporadic PD, particularly as genetic backgrounds vary widely by race. The Global Parkinson's Genetics Program is a global undertaking meant to address the issue of regional differences in genetic studies of PD.
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Affiliation(s)
- Manabu Funayama
- Research Institute of Disease of Old Age, Graduate School of Medicine, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
- Department of Neurology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
| | - Kenya Nishioka
- Department of Neurology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Yuanzhe Li
- Department of Neurology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Nobutaka Hattori
- Research Institute of Disease of Old Age, Graduate School of Medicine, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
- Department of Neurology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
- Neurodegenerative Disorders Collaborative Laboratory, RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama, 351-0106, Japan
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5
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Viering DH, Hureaux M, Neveling K, Latta F, Kwint M, Blanchard A, Konrad M, Bindels RJ, Schlingmann KP, Vargas-Poussou R, de Baaij JH. Long-Read Sequencing Identifies Novel Pathogenic Intronic Variants in Gitelman Syndrome. J Am Soc Nephrol 2023; 34:333-345. [PMID: 36302598 PMCID: PMC10103101 DOI: 10.1681/asn.2022050627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 10/17/2022] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Gitelman syndrome is a salt-losing tubulopathy characterized by hypokalemic alkalosis and hypomagnesemia. It is caused by homozygous recessive or compound heterozygous pathogenic variants in SLC12A3 , which encodes the Na + -Cl - cotransporter (NCC). In up to 10% of patients with Gitelman syndrome, current genetic techniques detect only one specific pathogenic variant. This study aimed to identify a second pathogenic variant in introns, splice sites, or promoters to increase the diagnostic yield. METHODS Long-read sequencing of SLC12A3 was performed in 67 DNA samples from individuals with suspected Gitelman syndrome in whom a single likely pathogenic or pathogenic variant was previously detected. In addition, we sequenced DNA samples from 28 individuals with one variant of uncertain significance or no candidate variant. Midigene splice assays assessed the pathogenicity of novel intronic variants. RESULTS A second likely pathogenic/pathogenic variant was identified in 45 (67%) patients. Those with two likely pathogenic/pathogenic variants had a more severe electrolyte phenotype than other patients. Of the 45 patients, 16 had intronic variants outside of canonic splice sites (nine variants, mostly deep intronic, six novel), whereas 29 patients had an exonic variant or canonic splice site variant. Midigene splice assays of the previously known c.1670-191C>T variant and intronic candidate variants demonstrated aberrant splicing patterns. CONCLUSION Intronic pathogenic variants explain an important part of the missing heritability in Gitelman syndrome. Long-read sequencing should be considered in diagnostic workflows for Gitelman syndrome.
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Affiliation(s)
- Daan H.H.M. Viering
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Marguerite Hureaux
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies Rénales Héréditaires de l’Enfant et de l’Adulte, MARHEA), Paris, France
- Department of Genetics, Hôpital Européen Georges-Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France
- Paris CardioVascular Research Center, Institut National de la Santé et de Recherche Médicale (INSERM) U970, Paris City University, Paris, France
| | - Kornelia Neveling
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Femke Latta
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Michael Kwint
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Anne Blanchard
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies Rénales Héréditaires de l’Enfant et de l’Adulte, MARHEA), Paris, France
- Clinical Investigations Center, Hôpital Européen Georges-Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, University of Paris, Centre National de la Recherche Scientifique (CNRS), Paris, France
| | - Martin Konrad
- Department of General Pediatrics, University Children’s Hospital, Münster, Germany
| | - René J.M. Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | | | - Rosa Vargas-Poussou
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies Rénales Héréditaires de l’Enfant et de l’Adulte, MARHEA), Paris, France
- Department of Genetics, Hôpital Européen Georges-Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France
- Clinical Investigations Center, Hôpital Européen Georges-Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France
| | - Jeroen H.F. de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
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6
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Wojcik MH, Reuter CM, Marwaha S, Mahmoud M, Duyzend MH, Barseghyan H, Yuan B, Boone PM, Groopman EE, Délot EC, Jain D, Sanchis-Juan A, Starita LM, Talkowski M, Montgomery SB, Bamshad MJ, Chong JX, Wheeler MT, Berger SI, O’Donnell-Luria A, Sedlazeck FJ, Miller DE. Beyond the exome: what's next in diagnostic testing for Mendelian conditions. ARXIV 2023:arXiv:2301.07363v1. [PMID: 36713248 PMCID: PMC9882576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Despite advances in clinical genetic testing, including the introduction of exome sequencing (ES), more than 50% of individuals with a suspected Mendelian condition lack a precise molecular diagnosis. Clinical evaluation is increasingly undertaken by specialists outside of clinical genetics, often occurring in a tiered fashion and typically ending after ES. The current diagnostic rate reflects multiple factors, including technical limitations, incomplete understanding of variant pathogenicity, missing genotype-phenotype associations, complex gene-environment interactions, and reporting differences between clinical labs. Maintaining a clear understanding of the rapidly evolving landscape of diagnostic tests beyond ES, and their limitations, presents a challenge for non-genetics professionals. Newer tests, such as short-read genome or RNA sequencing, can be challenging to order and emerging technologies, such as optical genome mapping and long-read DNA or RNA sequencing, are not available clinically. Furthermore, there is no clear guidance on the next best steps after inconclusive evaluation. Here, we review why a clinical genetic evaluation may be negative, discuss questions to be asked in this setting, and provide a framework for further investigation, including the advantages and disadvantages of new approaches that are nascent in the clinical sphere. We present a guide for the next best steps after inconclusive molecular testing based upon phenotype and prior evaluation, including when to consider referral to a consortium such as GREGoR, which is focused on elucidating the underlying cause of rare unsolved genetic disorders.
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Affiliation(s)
- Monica H. Wojcik
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
- Division of Genetics and Genomics, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115 USA
- Division of Newborn Medicine, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Chloe M. Reuter
- Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA 94305 USA
| | - Shruti Marwaha
- Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA 94305 USA
| | - Medhat Mahmoud
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston TX 77030 USA
| | - Michael H. Duyzend
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
- Division of Genetics and Genomics, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115 USA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114 USA
| | - Hayk Barseghyan
- Center for Genetics Medicine Research, Children’s National Research Institute, Children’s National Hospital, Washington, DC 20010 USA
- Department of Genomics and Precision Medicine, School of Medicine and Health Sciences, George Washington University, Washington, DC 20037 USA
| | - Bo Yuan
- Department of Molecular and Human Genetics and Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston TX 77030 USA
| | - Philip M. Boone
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
- Division of Genetics and Genomics, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115 USA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114 USA
| | - Emily E. Groopman
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
- Division of Genetics and Genomics, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115 USA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114 USA
| | - Emmanuèle C. Délot
- Department of Genomics and Precision Medicine, School of Medicine and Health Sciences, George Washington University, Washington, DC 20037 USA
- Center for Genetics Medicine Research, Children’s National Research and Innovation Campus, Washington, DC, USA
- Department of Pediatrics, George Washington University, School of Medicine and Health Sciences, George Washington University, Washington, DC 20037 USA
| | - Deepti Jain
- Department of Biostatistics, School of Public Health, University of Washington, Seattle WA 98195 USA
| | - Alba Sanchis-Juan
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114 USA
| | | | - Lea M. Starita
- Brotman Baty Institute for Precision Medicine, University of Washington, Seattle, WA 98195 USA
- Department of Genome Sciences, University of Washington, Seattle, WA, 98195 USA
| | - Michael Talkowski
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114 USA
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA
| | - Stephen B. Montgomery
- Department of Biomedical Data Science, Stanford University School of Medicine, Stanford, CA 94305 USA
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305 USA
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305 USA
| | - Michael J. Bamshad
- Brotman Baty Institute for Precision Medicine, University of Washington, Seattle, WA 98195 USA
- Department of Genome Sciences, University of Washington, Seattle, WA, 98195 USA
- Department of Pediatrics, Division of Genetic Medicine, University of Washington, Seattle, WA 98195 USA
| | - Jessica X. Chong
- Brotman Baty Institute for Precision Medicine, University of Washington, Seattle, WA 98195 USA
- Department of Pediatrics, Division of Genetic Medicine, University of Washington, Seattle, WA 98195 USA
| | - Matthew T. Wheeler
- Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA 94305 USA
| | - Seth I. Berger
- Center for Genetics Medicine Research and Rare Disease Institute, Children’s National Hospital, Washington, DC 20010 USA
| | - Anne O’Donnell-Luria
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
- Division of Genetics and Genomics, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115 USA
- Center for Genomic Medicine, Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA 02114 USA
| | - Fritz J. Sedlazeck
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston TX 77030 USA
- Department of Computer Science, Rice University, 6100 Main Street, Houston, TX, 77005 USA
| | - Danny E. Miller
- Brotman Baty Institute for Precision Medicine, University of Washington, Seattle, WA 98195 USA
- Department of Pediatrics, Division of Genetic Medicine, University of Washington, Seattle, WA 98195 USA
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, 98195 USA
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7
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Postel MD, Culver JO, Ricker C, Craig DW. Transcriptome analysis provides critical answers to the "variants of uncertain significance" conundrum. Hum Mutat 2022; 43:1590-1608. [PMID: 35510381 PMCID: PMC9560997 DOI: 10.1002/humu.24394] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 03/16/2022] [Accepted: 04/26/2022] [Indexed: 12/30/2022]
Abstract
While whole-genome and exome sequencing have transformed our collective understanding of genetics' role in disease pathogenesis, there are certain conditions and populations for whom DNA-level data fails to identify the underlying genetic etiology. Specifically, patients of non-White race and non-European ancestry are disproportionately affected by "variants of unknown/uncertain significance" (VUS), limiting the scope of precision medicine for minority patients and perpetuating health disparities. VUS often include deep intronic and splicing variants which are difficult to interpret from DNA data alone. RNA analysis can illuminate the consequences of VUS, thereby allowing for their reclassification as pathogenic versus benign. Here we review the critical role transcriptome analysis plays in clarifying VUS in both neoplastic and non-neoplastic diseases.
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Affiliation(s)
- Mackenzie D. Postel
- Department of Translational GenomicsUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
- Keck School of Medicine of USCUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
| | - Julie O. Culver
- Keck School of Medicine of USCUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
| | - Charité Ricker
- Keck School of Medicine of USCUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
| | - David W. Craig
- Department of Translational GenomicsUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
- Keck School of Medicine of USCUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
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Han Y, Zhu K, Wu H, Chen B, Hu S, Lai D, Tou J. Case Report: Novel JAG1 gene mutations in two infants with alagille syndrome characterized by cholestasis. Front Pediatr 2022; 10:1017647. [PMID: 36340723 PMCID: PMC9631024 DOI: 10.3389/fped.2022.1017647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 09/26/2022] [Indexed: 11/16/2022] Open
Abstract
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.
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Affiliation(s)
- Yijiang Han
- Department of Neonatal Surgery, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Kun Zhu
- Department of Pathology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Hao Wu
- The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Baohai Chen
- Department of Information Center, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Shuqi Hu
- Department of Neonatal Surgery, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Dengming Lai
- Department of Neonatal Surgery, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Jinfa Tou
- Department of Neonatal Surgery, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
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9
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Austin-Tse CA, Jobanputra V, Perry DL, Bick D, Taft RJ, Venner E, Gibbs RA, Young T, Barnett S, Belmont JW, Boczek N, Chowdhury S, Ellsworth KA, Guha S, Kulkarni S, Marcou C, Meng L, Murdock DR, Rehman AU, Spiteri E, Thomas-Wilson A, Kearney HM, Rehm HL. Best practices for the interpretation and reporting of clinical whole genome sequencing. NPJ Genom Med 2022; 7:27. [PMID: 35395838 PMCID: PMC8993917 DOI: 10.1038/s41525-022-00295-z] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 02/17/2022] [Indexed: 01/19/2023] Open
Abstract
Whole genome sequencing (WGS) shows promise as a first-tier diagnostic test for patients with rare genetic disorders. However, standards addressing the definition and deployment practice of a best-in-class test are lacking. To address these gaps, the Medical Genome Initiative, a consortium of leading health care and research organizations in the US and Canada, was formed to expand access to high quality clinical WGS by convening experts and publishing best practices. Here, we present best practice recommendations for the interpretation and reporting of clinical diagnostic WGS, including discussion of challenges and emerging approaches that will be critical to harness the full potential of this comprehensive test.
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Affiliation(s)
- Christina A Austin-Tse
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA. .,Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine, Cambridge, MA, USA. .,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA.
| | - Vaidehi Jobanputra
- Molecular Diagnostics Laboratory, New York Genome Center, New York, NY, USA.,Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
| | | | - David Bick
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, USA
| | | | - Eric Venner
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
| | - Richard A Gibbs
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
| | - Ted Young
- Genome Diagnostics, Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, ON, Canada
| | - Sarah Barnett
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | | | - Nicole Boczek
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA.,Center for Individualized Medicine, College of Medicine, Mayo Clinic, Rochester, MN, USA
| | - Shimul Chowdhury
- Rady Children's Institute for Genomic Medicine, San Diego, CA, USA
| | | | - Saurav Guha
- Molecular Diagnostics Laboratory, New York Genome Center, New York, NY, USA
| | - Shashikant Kulkarni
- Baylor Genetics and Baylor College of Medicine, Houston, TX, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Cherisse Marcou
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Linyan Meng
- Baylor Genetics and Baylor College of Medicine, Houston, TX, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - David R Murdock
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Atteeq U Rehman
- Molecular Diagnostics Laboratory, New York Genome Center, New York, NY, USA
| | - Elizabeth Spiteri
- Department of Pathology, Stanford Medicine, Stanford University, Stanford, CA, USA
| | | | - Hutton M Kearney
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Heidi L Rehm
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
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10
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Morton SU, Quiat D, Seidman JG, Seidman CE. Genomic frontiers in congenital heart disease. Nat Rev Cardiol 2022; 19:26-42. [PMID: 34272501 PMCID: PMC9236191 DOI: 10.1038/s41569-021-00587-4] [Citation(s) in RCA: 75] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/07/2021] [Indexed: 02/06/2023]
Abstract
The application of next-generation sequencing to study congenital heart disease (CHD) is increasingly providing new insights into the causes and mechanisms of this prevalent birth anomaly. Whole-exome sequencing analysis identifies damaging gene variants altering single or contiguous nucleotides that are assigned pathogenicity based on statistical analyses of families and cohorts with CHD, high expression in the developing heart and depletion of damaging protein-coding variants in the general population. Gene classes fulfilling these criteria are enriched in patients with CHD and extracardiac abnormalities, evidencing shared pathways in organogenesis. Developmental single-cell transcriptomic data demonstrate the expression of CHD-associated genes in particular cell lineages, and emerging insights indicate that genetic variants perturb multicellular interactions that are crucial for cardiogenesis. Whole-genome sequencing analyses extend these observations, identifying non-coding variants that influence the expression of genes associated with CHD and contribute to the estimated ~55% of unexplained cases of CHD. These approaches combined with the assessment of common and mosaic genetic variants have provided a more complete knowledge of the causes and mechanisms of CHD. Such advances provide knowledge to inform the clinical care of patients with CHD or other birth defects and deepen our understanding of the complexity of human development. In this Review, we highlight known and candidate CHD-associated human genes and discuss how the integration of advances in developmental biology research can provide new insights into the genetic contributions to CHD.
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Affiliation(s)
- Sarah U. Morton
- Division of Newborn Medicine, Department of Medicine, Boston Children’s Hospital, Boston, MA, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA.,These authors contributed equally: Sarah U. Morton, Daniel Quiat
| | - Daniel Quiat
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA.,Department of Cardiology, Boston Children’s Hospital, Boston, MA, USA.,These authors contributed equally: Sarah U. Morton, Daniel Quiat
| | | | - Christine E. Seidman
- Department of Genetics, Harvard Medical School, Boston, MA, USA.,Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA, USA.,Howard Hughes Medical Institute, Harvard University, Boston, MA, USA.,
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11
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Ranucci G, Della Corte C, Alberti D, Bondioni MP, Boroni G, Calvo PL, Cananzi M, Candusso M, Clemente MG, D'Antiga L, Degrassi I, De Ville De Goyet J, Di Dato F, Di Giorgio A, Vici CD, Ferrari F, Francalanci P, Fuoti M, Fusaro F, Gaio P, Grimaldi C, Iascone M, Indolfi G, Iorio R, Maggiore G, Mandato C, Matarazzo L, Monti L, Mosca F, Nebbia G, Nuti F, Paolella G, Pinon M, Roggero P, Sciveres M, Serranti D, Spada M, Vajro P, Nicastro E. Diagnostic approach to neonatal and infantile cholestasis: A position paper by the SIGENP liver disease working group. Dig Liver Dis 2022; 54:40-53. [PMID: 34688573 DOI: 10.1016/j.dld.2021.09.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 08/23/2021] [Accepted: 09/12/2021] [Indexed: 12/11/2022]
Abstract
Neonatal and infantile cholestasis (NIC) can represent the onset of a surgically correctable disease and of a genetic or metabolic disorder worthy of medical treatment. Timely recognition of NIC and identification of the underlying etiology are paramount to improve outcomes. Upon invitation by the Italian National Institute of Health (ISS), an expert working grouped was formed to formulate evidence-based positions on current knowledge about the diagnosis of NIC. A systematic literature search was conducted to collect evidence about epidemiology, etiology, clinical aspects and accuracy of available diagnostic tests in NIC. Evidence was scored using the GRADE system. All recommendations were approved by a panel of experts upon agreement of at least 75% of the members. The final document was approved by all the panel components. This position document summarizes the collected statements and defines the best-evidence diagnostic approach to cholestasis in the first year of life.
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Affiliation(s)
- Giusy Ranucci
- Department of Pediatrics, Santobono-Pausilipon Children's Hospital AORN, Naples, Italy
| | - Claudia Della Corte
- Hepatology, Gastroenterology, Nutrition and Liver transplantation Unit, Bambino Gesù Children's Hospital IRCCS, Rome, Italy
| | | | - Maria Pia Bondioni
- Pediatric Radiology, University of Brescia, ASST Spedali Civili di Brescia, Brescia, Italy
| | | | - Pier Luigi Calvo
- Pediatric Gastroenterology Unit, Regina Margherita Children's Hospital, Azienda Ospedaliera-Universitaria Città della Salute e della Scienza, Turin, Italy
| | - Mara Cananzi
- Unit of Gastroenterology, Digestive Endoscopy, Hepatology and Care of Children with Liver Transplantation, University Hospital of Padova, Padova, Italy
| | - Manila Candusso
- Hepatology, Gastroenterology, Nutrition and Liver transplantation Unit, Bambino Gesù Children's Hospital IRCCS, Rome, Italy
| | - Maria Grazia Clemente
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy
| | - Lorenzo D'Antiga
- Hepatology, Gastroenterology and Transplantation Unit, Hospital Papa Giovanni XXIII, Bergamo, Italy
| | - Irene Degrassi
- Service of Paediatric Hepatology, Department of Paediatrics, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Jean De Ville De Goyet
- Pediatric Department for the Treatment and Study of Abdominal Diseases and Abdominal Transplantation, ISMETT UPMC, Palermo, Italy
| | - Fabiola Di Dato
- Department di Translational Medical Science, School of Medicine and Surgery, University of Naples Federico II, Naples, Italy
| | - Angelo Di Giorgio
- Hepatology, Gastroenterology and Transplantation Unit, Hospital Papa Giovanni XXIII, Bergamo, Italy
| | - Carlo Dionisi Vici
- Division of Metabolism and Metabolic Diseases Research Unit, Bambino Gesù Children's Hospital IRCCS, Rome, Italy
| | | | - Paola Francalanci
- Department of Pathology, Bambino Gesù Children's Hospital IRCCS, Rome, Italy
| | - Maurizio Fuoti
- Pediatric Gastroenterology and Endoscopy Unit Children's Hospital, ASST Spedali Civili di Brescia, Brescia, Italy
| | - Fabio Fusaro
- Department of Medical and Surgical Neonatology, Bambino Gesù Children's Hospital IRCCS, Rome, Italy
| | - Paola Gaio
- Unit of Gastroenterology, Digestive Endoscopy, Hepatology and Care of Children with Liver Transplantation, University Hospital of Padova, Padova, Italy
| | - Chiara Grimaldi
- Division of Abdominal Transplantation and Hepatobiliopancreatic Surgery, Bambino Gesù Children's Hospital IRCCS, Rome, Italy
| | - Maria Iascone
- Medical Genetics Laboratory, Hospital Papa Giovanni XXIII, Bergamo, Italy
| | - Giuseppe Indolfi
- Department of Pediatrics, Meyer Children's University Hospital, Florence, Italy
| | - Raffaele Iorio
- Department di Translational Medical Science, School of Medicine and Surgery, University of Naples Federico II, Naples, Italy
| | - Giuseppe Maggiore
- Hepatology, Gastroenterology, Nutrition and Liver transplantation Unit, Bambino Gesù Children's Hospital IRCCS, Rome, Italy
| | - Claudia Mandato
- Department of Pediatrics, Santobono-Pausilipon Children's Hospital AORN, Naples, Italy
| | | | - Lidia Monti
- Department of Radiology, Bambino Gesù Children's Hospital IRCCS, Rome, Italy
| | - Fabio Mosca
- Neonatal Intensive Care Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Gabriella Nebbia
- Service of Paediatric Hepatology, Department of Paediatrics, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Federica Nuti
- Service of Paediatric Hepatology, Department of Paediatrics, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Giulia Paolella
- Service of Paediatric Hepatology, Department of Paediatrics, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Michele Pinon
- Pediatric Gastroenterology Unit, Regina Margherita Children's Hospital, Azienda Ospedaliera-Universitaria Città della Salute e della Scienza, Turin, Italy
| | - Paola Roggero
- Neonatal Intensive Care Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Marco Sciveres
- Pediatric Hepatology and Liver Transplantation, ISMETT UPMC, Palermo, Italy
| | - Daniele Serranti
- Department of Pediatrics, Meyer Children's University Hospital, Florence, Italy
| | - Marco Spada
- Division of Abdominal Transplantation and Hepatobiliopancreatic Surgery, Bambino Gesù Children's Hospital IRCCS, Rome, Italy
| | - Pietro Vajro
- Department of Medicine, Surgery and Dentistry, "Scuola Medica Salernitana" University of Salerno, Baronissi, Italy
| | - Emanuele Nicastro
- Hepatology, Gastroenterology and Transplantation Unit, Hospital Papa Giovanni XXIII, Bergamo, Italy
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12
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Kohut TJ, Gilbert MA, Loomes KM. Alagille Syndrome: A Focused Review on Clinical Features, Genetics, and Treatment. Semin Liver Dis 2021; 41:525-537. [PMID: 34215014 DOI: 10.1055/s-0041-1730951] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
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.
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Affiliation(s)
- Taisa J Kohut
- Division of Gastroenterology, Hepatology, and Nutrition, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Melissa A Gilbert
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Kathleen M Loomes
- Division of Gastroenterology, Hepatology, and Nutrition, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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13
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Umlai UKI, Bangarusamy DK, Estivill X, Jithesh PV. Genome sequencing data analysis for rare disease gene discovery. Brief Bioinform 2021; 23:6366880. [PMID: 34498682 DOI: 10.1093/bib/bbab363] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 07/24/2021] [Accepted: 08/17/2021] [Indexed: 12/14/2022] Open
Abstract
Rare diseases occur in a smaller proportion of the general population, which is variedly defined as less than 200 000 individuals (US) or in less than 1 in 2000 individuals (Europe). Although rare, they collectively make up to approximately 7000 different disorders, with majority having a genetic origin, and affect roughly 300 million people globally. Most of the patients and their families undergo a long and frustrating diagnostic odyssey. However, advances in the field of genomics have started to facilitate the process of diagnosis, though it is hindered by the difficulty in genome data analysis and interpretation. A major impediment in diagnosis is in the understanding of the diverse approaches, tools and datasets available for variant prioritization, the most important step in the analysis of millions of variants to select a few potential variants. Here we present a review of the latest methodological developments and spectrum of tools available for rare disease genetic variant discovery and recommend appropriate data interpretation methods for variant prioritization. We have categorized the resources based on various steps of the variant interpretation workflow, starting from data processing, variant calling, annotation, filtration and finally prioritization, with a special emphasis on the last two steps. The methods discussed here pertain to elucidating the genetic basis of disease in individual patient cases via trio- or family-based analysis of the genome data. We advocate the use of a combination of tools and datasets and to follow multiple iterative approaches to elucidate the potential causative variant.
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Affiliation(s)
- Umm-Kulthum Ismail Umlai
- Division of Genomics & Translational Biomedicine, College of Health & Life Sciences, Hamad Bin Khalifa University, B-147, Penrose House, PO Box 34110, Education City, Doha, Qatar
| | - Dhinoth Kumar Bangarusamy
- Division of Genomics & Translational Biomedicine, College of Health & Life Sciences, Hamad Bin Khalifa University, B-147, Penrose House, PO Box 34110, Education City, Doha, Qatar
| | - Xavier Estivill
- Quantitative Genomics Laboratories (qGenomics), Barcelona, Catalonia, Spain
| | - Puthen Veettil Jithesh
- Division of Genomics & Translational Biomedicine, College of Health & Life Sciences, Hamad Bin Khalifa University, B-147, Penrose House, PO Box 34110, Education City, Doha, Qatar
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14
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Genomic Aberrations Associated with the Pathophysiological Mechanisms of Neurodevelopmental Disorders. Cells 2021; 10:cells10092317. [PMID: 34571966 PMCID: PMC8470284 DOI: 10.3390/cells10092317] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/30/2021] [Accepted: 09/03/2021] [Indexed: 12/27/2022] Open
Abstract
Genomic studies are increasingly revealing that neurodevelopmental disorders are caused by underlying genomic alterations. Chromosomal microarray testing has been used to reliably detect minute changes in genomic copy numbers. The genes located in the aberrated regions identified in patients with neurodevelopmental disorders may be associated with the phenotypic features. In such cases, haploinsufficiency is considered to be the mechanism, when the deletion of a gene is related to neurodevelopmental delay. The loss-of-function mutation in such genes may be evaluated using next-generation sequencing. On the other hand, the patients with increased copy numbers of the genes may exhibit different clinical symptoms compared to those with loss-of-function mutation in the genes. In such cases, the additional copies of the genes are considered to have a dominant negative effect, inducing cell stress. In other cases, not the copy number changes, but mutations of the genes are responsible for causing the clinical symptoms. This can be explained by the dominant negative effects of the gene mutations. Currently, the diagnostic yield of genomic alterations using comprehensive analysis is less than 50%, indicating the existence of more subtle alterations or genomic changes in the untranslated regions. Copy-neutral inversions and insertions may be related. Hence, better analytical algorithms specialized for the detection of such alterations are required for higher diagnostic yields.
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