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Richter F, Rutherford KD, Cooke AJ, Meshkati M, Eddy-Abrams V, Greene D, Kosowsky J, Park Y, Aggarwal S, Burke RJ, Chang W, Connors J, Giannone PJ, Hays T, Khattar D, Polak M, Senaldi L, Smith-Raska M, Sridhar S, Steiner L, Swanson JR, Tauber KA, Barbosa M, Guttmann KF, Turro E. A Deep Intronic PKHD1 Variant Identified by SpliceAI in a Deceased Neonate With Autosomal Recessive Polycystic Kidney Disease. Am J Kidney Dis 2024; 83:829-833. [PMID: 38211685 PMCID: PMC11116050 DOI: 10.1053/j.ajkd.2023.12.011] [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: 07/31/2023] [Revised: 10/09/2023] [Accepted: 11/10/2023] [Indexed: 01/13/2024]
Abstract
The etiologies of newborn deaths in neonatal intensive care units usually remain unknown, even after genetic testing. Whole-genome sequencing, combined with artificial intelligence-based methods for predicting the effects of non-coding variants, provide an avenue for resolving these deaths. Using one such method, SpliceAI, we identified a maternally inherited deep intronic PKHD1 splice variant (chr6:52030169T>C), in trans with a pathogenic missense variant (p.Thr36Met), in a newborn who died of autosomal recessive polycystic kidney disease at age 2 days. We validated the deep intronic variant's impact in maternal urine-derived cells expressing PKHD1. Reverse transcription polymerase chain reaction followed by Sanger sequencing showed that the variant causes inclusion of 147bp of the canonical intron between exons 29 and 30 of PKHD1 into the mRNA, including a premature stop codon. Allele-specific expression analysis at a heterozygous site in the mother showed that the mutant allele completely suppresses canonical splicing. In an unrelated healthy control, there was no evidence of transcripts including the novel splice junction. We returned a diagnostic report to the parents, who underwent in vitro embryo selection.
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Affiliation(s)
- Felix Richter
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York; Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Kayleigh D Rutherford
- Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Anisha J Cooke
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Malorie Meshkati
- Division of Newborn Medicine, Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Vanessa Eddy-Abrams
- Division of Newborn Medicine, Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Daniel Greene
- Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jordana Kosowsky
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Yeaji Park
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Surabhi Aggarwal
- Division of Neonatology, Department of Pediatrics, Stony Brook Children's Hospital, New York, New York
| | - Rebecca J Burke
- Department of Pediatrics, Penn State Health Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Weili Chang
- Department of Neonatology, Pediatrics, East Carolina University, Greenville, North Carolina
| | - Jillian Connors
- Division of Neonatology, The Children's Hospital at Montefiore, Bronx, New York
| | - Peter J Giannone
- Division of Neonatology, Department of Pediatrics, University of Kentucky, Lexington, Kentucky
| | - Thomas Hays
- Division of Neonatology, Department of Pediatrics, Columbia University Irving Medical Center, New York, New York
| | - Divya Khattar
- Division of Neonatology, Department of Pediatrics, University of Kentucky, Lexington, Kentucky
| | - Mark Polak
- Department of Pediatrics, Division of Neonatology, West Virginia University School of Medicine, Morgantown, West Virginia
| | - Liana Senaldi
- Division of Newborn Medicine, Department of Pediatrics, Weill Cornell Medicine, New York-Presbyterian Hospital, New York, New York
| | - Matthew Smith-Raska
- Division of Newborn Medicine, Department of Pediatrics, Weill Cornell Medicine, New York-Presbyterian Hospital, New York, New York
| | - Shanthy Sridhar
- Division of Neonatology, Department of Pediatrics, Stony Brook Children's Hospital, New York, New York
| | - Laurie Steiner
- Department of Pediatrics, University of Rochester, Rochester, New York
| | - Jonathan R Swanson
- Division of Neonatology, Department of Pediatrics, University of Virginia Children's Hospital, Charlottesville, Virginia
| | - Kate A Tauber
- Department of Pediatrics, Albany Medical Center, Albany, New York
| | - Mafalda Barbosa
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York; Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Katherine F Guttmann
- Division of Newborn Medicine, Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Ernest Turro
- Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York; Charles Bronfman Institute for Personalized Medicine, Icahn School of Medicine at Mount Sinai, New York, New York.
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Boerrigter MM, te Morsche RHM, Venselaar H, Pastoors N, Geerts AM, Hoorens A, Drenth JPH. Novel α-1,3-Glucosyltransferase Variants and Their Broad Clinical Polycystic Liver Disease Spectrum. Genes (Basel) 2023; 14:1652. [PMID: 37628703 PMCID: PMC10454741 DOI: 10.3390/genes14081652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 08/16/2023] [Accepted: 08/17/2023] [Indexed: 08/27/2023] Open
Abstract
Protein-truncating variants in α-1,3-glucosyltransferase (ALG8) are a risk factor for a mild cystic kidney disease phenotype. The association between these variants and liver cysts is limited. We aim to identify pathogenic ALG8 variants in our cohort of autosomal dominant polycystic liver disease (ADPLD) individuals. In order to fine-map the phenotypical spectrum of pathogenic ALG8 variant carriers, we performed targeted ALG8 screening in 478 ADPLD singletons, and exome sequencing in 48 singletons and 4 patients from two large ADPLD families. Eight novel and one previously reported pathogenic variant in ALG8 were discovered in sixteen patients. The ALG8 clinical phenotype ranges from mild to severe polycystic liver disease, and from innumerable small to multiple large hepatic cysts. The presence of <5 renal cysts that do not affect renal function is common in this population. Three-dimensional homology modeling demonstrated that six variants cause a truncated ALG8 protein with abnormal functioning, and one variant is predicted to destabilize ALG8. For the seventh variant, immunostaining of the liver tissue showed a complete loss of ALG8 in the cystic cells. ALG8-associated ADPLD has a broad clinical spectrum, including the possibility of developing a small number of renal cysts. This broadens the ADPLD genotype-phenotype spectrum and narrows the gap between liver-specific ADPLD and kidney-specific ADPKD.
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Affiliation(s)
- Melissa M. Boerrigter
- Department of Gastroenterology and Hepatology, Research Institute for Medical Innovation, Radboud University Medical Center, 6500 HB Nijmegen, The Netherlands
| | - René H. M. te Morsche
- Department of Gastroenterology and Hepatology, Research Institute for Medical Innovation, Radboud University Medical Center, 6500 HB Nijmegen, The Netherlands
| | - Hanka Venselaar
- Center for Molecular and Biomolecular Informatics, Research Institute for Medical Innovation, 6500 HB Nijmegen, The Netherlands
| | - Nikki Pastoors
- Department of Gastroenterology and Hepatology, Research Institute for Medical Innovation, Radboud University Medical Center, 6500 HB Nijmegen, The Netherlands
| | - Anja M. Geerts
- Department of Gastroenterology and Hepatology, Ghent University Hospital, 9000 Ghent, Belgium
| | - Anne Hoorens
- Department of Pathology, Ghent University Hospital, 9000 Ghent, Belgium
| | - Joost P. H. Drenth
- Department of Gastroenterology and Hepatology, Research Institute for Medical Innovation, Radboud University Medical Center, 6500 HB Nijmegen, The Netherlands
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3
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Nabavizadeh N, Bressin A, Shboul M, Moreno Traspas R, Chia PH, Bonnard C, Szenker‐Ravi E, Sarıbaş B, Beillard E, Altunoglu U, Hojati Z, Drutman S, Freier S, El‐Khateeb M, Fathallah R, Casanova J, Soror W, Arafat A, Escande‐Beillard N, Mayer A, Reversade B. A progeroid syndrome caused by a deep intronic variant in TAPT1 is revealed by RNA/SI-NET sequencing. EMBO Mol Med 2023; 15:e16478. [PMID: 36652330 PMCID: PMC9906387 DOI: 10.15252/emmm.202216478] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 12/13/2022] [Accepted: 12/14/2022] [Indexed: 01/19/2023] Open
Abstract
Exome sequencing has introduced a paradigm shift for the identification of germline variations responsible for Mendelian diseases. However, non-coding regions, which make up 98% of the genome, cannot be captured. The lack of functional annotation for intronic and intergenic variants makes RNA-seq a powerful companion diagnostic. Here, we illustrate this point by identifying six patients with a recessive Osteogenesis Imperfecta (OI) and neonatal progeria syndrome. By integrating homozygosity mapping and RNA-seq, we delineated a deep intronic TAPT1 mutation (c.1237-52 G>A) that segregated with the disease. Using SI-NET-seq, we document that TAPT1's nascent transcription was not affected in patients' fibroblasts, indicating instead that this variant leads to an alteration of pre-mRNA processing. Predicted to serve as an alternative splicing branchpoint, this mutation enhances TAPT1 exon 12 skipping, creating a protein-null allele. Additionally, our study reveals dysregulation of pathways involved in collagen and extracellular matrix biology in disease-relevant cells. Overall, our work highlights the power of transcriptomic approaches in deciphering the repercussions of non-coding variants, as well as in illuminating the molecular mechanisms of human diseases.
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Affiliation(s)
- Nasrinsadat Nabavizadeh
- Laboratory of Human Genetics & TherapeuticsGenome Institute of Singapore, A*STARSingapore CitySingapore
- Division of Genetics, Department of Cell and Molecular Biology & Microbiology, Faculty of Biological Science and TechnologyUniversity of IsfahanIsfahanIran
- Medical Genetics DepartmentKoç University School of MedicineIstanbulTurkey
| | | | - Mohammad Shboul
- Department of Medical Laboratory SciencesJordan University of Science and TechnologyIrbidJordan
| | - Ricardo Moreno Traspas
- Laboratory of Human Genetics & TherapeuticsGenome Institute of Singapore, A*STARSingapore CitySingapore
| | - Poh Hui Chia
- Laboratory of Human Genetics & TherapeuticsGenome Institute of Singapore, A*STARSingapore CitySingapore
| | - Carine Bonnard
- Model Development, A*STAR Skin Research Labs (A*SRL)Singapore CitySingapore
| | - Emmanuelle Szenker‐Ravi
- Laboratory of Human Genetics & TherapeuticsGenome Institute of Singapore, A*STARSingapore CitySingapore
| | - Burak Sarıbaş
- Laboratory of Human Genetics & TherapeuticsGenome Institute of Singapore, A*STARSingapore CitySingapore
- Medical Genetics DepartmentKoç University School of MedicineIstanbulTurkey
| | | | - Umut Altunoglu
- Medical Genetics DepartmentKoç University School of MedicineIstanbulTurkey
| | - Zohreh Hojati
- Division of Genetics, Department of Cell and Molecular Biology & Microbiology, Faculty of Biological Science and TechnologyUniversity of IsfahanIsfahanIran
| | - Scott Drutman
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller BranchRockefeller UniversityNew YorkNYUSA
| | - Susanne Freier
- Max Planck Institute for Molecular GeneticsBerlinGermany
| | | | - Rajaa Fathallah
- National Center for Diabetes, Endocrinology and GeneticsAmmanJordan
| | - Jean‐Laurent Casanova
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller BranchRockefeller UniversityNew YorkNYUSA
- Laboratory of Human Genetics of Infectious Diseases, Necker BranchINSERM U1163, Necker Hospital for Sick ChildrenParisFrance
- Imagine InstituteUniversity of ParisParisFrance
- Howard Hughes Medical InstituteNew YorkNYUSA
- Pediatric Hematology and Immunology UnitNecker Hospital for Sick ChildrenParisFrance
| | - Wesam Soror
- National Center for Diabetes, Endocrinology and GeneticsAmmanJordan
| | - Alaa Arafat
- National Center for Diabetes, Endocrinology and GeneticsAmmanJordan
| | - Nathalie Escande‐Beillard
- Medical Genetics DepartmentKoç University School of MedicineIstanbulTurkey
- Institute of Molecular and Cell Biology, A*STARSingapore CitySingapore
| | - Andreas Mayer
- Max Planck Institute for Molecular GeneticsBerlinGermany
| | - Bruno Reversade
- Laboratory of Human Genetics & TherapeuticsGenome Institute of Singapore, A*STARSingapore CitySingapore
- Medical Genetics DepartmentKoç University School of MedicineIstanbulTurkey
- Institute of Molecular and Cell Biology, A*STARSingapore CitySingapore
- Department of PaediatricsNational University of SingaporeSingapore CitySingapore
- Smart‐Health Initiative, BESE, KAUSTThuwalKingdom of Saudi Arabia
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Keegan NP, Wilton SD, Fletcher S. Analysis of Pathogenic Pseudoexons Reveals Novel Mechanisms Driving Cryptic Splicing. Front Genet 2022; 12:806946. [PMID: 35140743 PMCID: PMC8819188 DOI: 10.3389/fgene.2021.806946] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 12/09/2021] [Indexed: 12/16/2022] Open
Abstract
Understanding pre-mRNA splicing is crucial to accurately diagnosing and treating genetic diseases. However, mutations that alter splicing can exert highly diverse effects. Of all the known types of splicing mutations, perhaps the rarest and most difficult to predict are those that activate pseudoexons, sometimes also called cryptic exons. Unlike other splicing mutations that either destroy or redirect existing splice events, pseudoexon mutations appear to create entirely new exons within introns. Since exon definition in vertebrates requires coordinated arrangements of numerous RNA motifs, one might expect that pseudoexons would only arise when rearrangements of intronic DNA create novel exons by chance. Surprisingly, although such mutations do occur, a far more common cause of pseudoexons is deep-intronic single nucleotide variants, raising the question of why these latent exon-like tracts near the mutation sites have not already been purged from the genome by the evolutionary advantage of more efficient splicing. Possible answers may lie in deep intronic splicing processes such as recursive splicing or poison exon splicing. Because these processes utilize intronic motifs that benignly engage with the spliceosome, the regions involved may be more susceptible to exonization than other intronic regions would be. We speculated that a comprehensive study of reported pseudoexons might detect alignments with known deep intronic splice sites and could also permit the characterisation of novel pseudoexon categories. In this report, we present and analyse a catalogue of over 400 published pseudoexon splice events. In addition to confirming prior observations of the most common pseudoexon mutation types, the size of this catalogue also enabled us to suggest new categories for some of the rarer types of pseudoexon mutation. By comparing our catalogue against published datasets of non-canonical splice events, we also found that 15.7% of pseudoexons exhibit some splicing activity at one or both of their splice sites in non-mutant cells. Importantly, this included seven examples of experimentally confirmed recursive splice sites, confirming for the first time a long-suspected link between these two splicing phenomena. These findings have the potential to improve the fidelity of genetic diagnostics and reveal new targets for splice-modulating therapies.
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Affiliation(s)
- Niall P. Keegan
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA, Australia
- *Correspondence: Niall P. Keegan,
| | - Steve D. Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA, Australia
| | - Sue Fletcher
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA, Australia
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Petersen USS, Doktor TK, Andresen BS. Pseudoexon activation in disease by non-splice site deep intronic sequence variation - wild type pseudoexons constitute high-risk sites in the human genome. Hum Mutat 2021; 43:103-127. [PMID: 34837434 DOI: 10.1002/humu.24306] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 11/02/2021] [Accepted: 11/06/2021] [Indexed: 12/27/2022]
Abstract
Accuracy of pre-messenger RNA (pre-mRNA) splicing is crucial for normal gene expression. Complex regulation supports the spliceosomal distinction between authentic exons and the many seemingly functional splice sites delimiting pseudoexons. Pseudoexons are nonfunctional intronic sequences that can be activated for aberrant inclusion in mRNA, which may cause disease. Pseudoexon activation is very challenging to predict, in particular when activation occurs by sequence variants that alter the splicing regulatory environment without directly affecting splice sites. As pseudoexon inclusion often evades detection due to activation of nonsense-mediated mRNA decay, and because conventional diagnostic procedures miss deep intronic sequence variation, pseudoexon activation is a heavily underreported disease mechanism. Pseudoexon characteristics have mainly been studied based on in silico predicted sequences. Moreover, because recognition of sequence variants that create or strengthen splice sites is possible by comparison with well-established consensus sequences, this type of pseudoexon activation is by far the most frequently reported. Here we review all known human disease-associated pseudoexons that carry functional splice sites and are activated by deep intronic sequence variants located outside splice site sequences. We delineate common characteristics that make this type of wild type pseudoexons distinct high-risk sites in the human genome.
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Affiliation(s)
- Ulrika S S Petersen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Thomas K Doktor
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
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Synofzik M, van Roon-Mom WMC, Marckmann G, van Duyvenvoorde HA, Graessner H, Schüle R, Aartsma-Rus A. Preparing n-of-1 Antisense Oligonucleotide Treatments for Rare Neurological Diseases in Europe: Genetic, Regulatory, and Ethical Perspectives. Nucleic Acid Ther 2021; 32:83-94. [PMID: 34591693 PMCID: PMC9058873 DOI: 10.1089/nat.2021.0039] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Antisense oligonucleotide (ASO) therapies present a promising disease-modifying treatment approach for rare neurological diseases (RNDs). However, the current focus is on "more common" RNDs, leaving a large share of RND patients still without prospect of disease-modifying treatments. In response to this gap, n-of-1 ASO treatment approaches are targeting ultrarare or even private variants. While highly attractive, this emerging, academia-driven field of ultimately individualized precision medicine is in need of systematic guidance and standards, which will allow global scaling of this approach. We provide here genetic, regulatory, and ethical perspectives for preparing n-of-1 ASO treatments and research programs, with a specific focus on the European context. By example of splice modulating ASOs, we outline genetic criteria for variant prioritization, chart the regulatory field of n-of-1 ASO treatment development in Europe, and propose an ethically informed classification for n-of-1 ASO treatment strategies and level of outcome assessments. To accommodate the ethical requirements of both individual patient benefit and knowledge gain, we propose a stronger integration of patient care and clinical research when developing novel n-of-1 ASO treatments: each single trial of therapy should inherently be driven to generate generalizable knowledge, be registered in a ASO treatment registry, and include assessment of generic outcomes, which allow aggregated analysis across n-of-1 trials of therapy.
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Affiliation(s)
- Matthis Synofzik
- Department of Neurodegenerative Diseases, Hertie-Institute for Clinical Brain Research and Center of Neurology, University of Tübingen, Tübingen, Germany.,Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | | | - Georg Marckmann
- Institute of Ethics, History and Theory of Medicine, Ludwig Maximilians University Munich, Munich, Germany
| | | | - Holm Graessner
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany.,Center for Rare Diseases, Tübingen, Germany
| | - Rebecca Schüle
- Department of Neurodegenerative Diseases, Hertie-Institute for Clinical Brain Research and Center of Neurology, University of Tübingen, Tübingen, Germany.,Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Annemieke Aartsma-Rus
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
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de Fallois J, Schönauer R, Münch J, Nagel M, Popp B, Halbritter J. Challenging Disease Ontology by Instances of Atypical PKHD1 and PKD1 Genetics. Front Genet 2021; 12:682565. [PMID: 34249099 PMCID: PMC8267867 DOI: 10.3389/fgene.2021.682565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 05/05/2021] [Indexed: 12/03/2022] Open
Abstract
Background Autosomal polycystic kidney disease is distinguished into dominant (ADPKD) and recessive (ARPKD) inheritance usually caused by either monoallelic (PKD1/PKD2) or biallelic (PKHD1) germline variation. Clinical presentations are genotype-dependent ranging from fetal demise to mild chronic kidney disease (CKD) in adults. Additionally, exemptions from dominant and recessive inheritance have been reported in both disorders resulting in respective phenocopies. Here, we comparatively report three young adults with microcystic-hyperechogenic kidney morphology based on unexpected genetic alterations beyond typical inheritance. Methods Next-generation sequencing (NGS)-based gene panel analysis and multiplex ligation-dependent probe amplification (MLPA) of PKD-associated genes, familial segregation analysis, and reverse phenotyping. Results Three unrelated individuals presented in late adolescence for differential diagnosis of incidental microcystic-hyperechogenic kidneys with preserved kidney and liver function. Upon genetic analysis, we identified a homozygous hypomorphic PKHD1 missense variant causing pseudodominant inheritance in a family, a large monoallelic PKDH1-deletion with atypical transmission, and biallelic PKD1 missense hypomorphs with recessive inheritance. Conclusion By this report, we illustrate clinical presentations associated with atypical PKD-gene alterations beyond traditional modes of inheritance. Large monoallelic PKHD1-alterations as well as biallelic hypomorphs of both PKD1 and PKHD1 may lead to mild CKD in the absence of prominent macrocyst formation and functional liver impairment. The long-term renal prognosis throughout life, however, remains undetermined. Increased detection of atypical inheritance challenges our current thinking of disease ontology not only in PKD but also in Mendelian disorders in general.
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Affiliation(s)
- Jonathan de Fallois
- Department of Endocrinology, Nephrology and Rheumatology, University of Leipzig Medical Center, Leipzig, Germany
| | - Ria Schönauer
- Department of Endocrinology, Nephrology and Rheumatology, University of Leipzig Medical Center, Leipzig, Germany
| | - Johannes Münch
- Department of Endocrinology, Nephrology and Rheumatology, University of Leipzig Medical Center, Leipzig, Germany
| | - Mato Nagel
- Center for Nephrology and Metabolic Disorders, Weißwasser, Germany
| | - Bernt Popp
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Jan Halbritter
- Department of Endocrinology, Nephrology and Rheumatology, University of Leipzig Medical Center, Leipzig, Germany
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Possible PKHD1 Hot-spot Mutations Related to Early Kidney Function Failure or Hepatofibrosis in Chinese Children with ARPKD: A Retrospective Single Center Cohort Study and Literature Review. Curr Med Sci 2020; 40:835-844. [PMID: 33123899 DOI: 10.1007/s11596-020-2268-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 08/23/2020] [Indexed: 10/23/2022]
Abstract
PKHD1 mutations are generally considered to cause autosomal recessive polycystic kidney disease (ARPKD). ARPKD is a rare disorder and one of the most severe conditions leading to end-stage renal disease in childhood. With the biallelic deletion mutation, patients have difficulty in surviving the perinatal period, resulting in perinatal or neonatal death. This study retrospectively analyzed patient characteristics, imaging characteristics, laboratory examinations and family surveys from 7 Chinese children with different PKHD1 gene mutations diagnosed by high-throughput sequencing from January 2014 to February 2018. Of the 7 children, there were 3 males and 4 females. Eight missense mutations, two frameshift mutations, two deletion mutations, and two intronic slicing mutations were identified. Six of the mutations have not previously been identified. In the literature search, we identified a total of 29 Chinese children with PKHD1 mutations. The missense mutation c.2507T>C in exon 24 was found in one patient in our study, and five patients with liver fibrosis but normal renal function were reported in the literature. The missense mutation c.5935G>A in exon 37 was found in two patients in our study and three cases in the literature. Four patients had renal failure at an age as young as 1 year of those five patients with the missense mutation c.5935G>A in exon 37. It was concluded that: (1) Kidney length more than 2-3 SDs above the mean and early-onset hypertension might be associated with PKHD1-associated ARPKD; (2) The more enlarged the kidney size is, the lower the renal function is likely to be; (3) c.5935G>A may be a hot spot that leads to early renal failure in Chinese children with PKHD1 mutations; (4) c.2507T>C may be a hot-spot mutation associated with hepatic lesions in Chinese children with PKHD1.
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