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Zhang Q, Yang S, Chen X, Wang H, Li K, Zhang C, Liao S, Qin L, Hou Q. Identification of novel TMEM231 gene splice variants and pathological findings in a fetus with Meckel Syndrome. Front Genet 2023; 14:1252873. [PMID: 37736303 PMCID: PMC10509762 DOI: 10.3389/fgene.2023.1252873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 08/22/2023] [Indexed: 09/23/2023] Open
Abstract
Background: Meckel Syndrome (MKS, OMIM #249000) is a rare and fatal autosomal recessive ciliopathy with high clinical and genetic heterogeneity. MKS shows complex allelism with other related ciliopathies such as Joubert Syndrome (JBTS, OMIM #213300). In MKS, the formation and function of the primary cilium is defective, resulting in a multisystem disorder including occipital encephalocele, polycystic kidneys, postaxial polydactyly, liver fibrosis, central nervous system malformations and genital anomalies. This study aimed to analyze the genotype of MKS patients and investigate the correlation between genotype and phenotype. Methods: A nonconsanguineous couple who conceived four times with a fetus affected by multiorgan dysfunction and intrauterine fetal death was studied. Whole exome sequencing (WES) was performed in the proband to identify the potentially pathogenic variant. Sanger sequencing was performed in family members. In silico tools were used to analyse the pathogenicity of the identified variants. cDNA TA-cloning sequencing was performed to validate the effects of intronic variants on mRNA splicing. Quantitative real-time PCR was performed to investigate the effect of the variants on gene expression. Immunofluorescence was performed to observe pathological changes of the primary cilium in kidney tissue from the proband. Results: Two splice site variants of TMEM231 (NM_001077418.2, c.583-1G>C and c.583-2_588delinsTCCTCCC) were identified in the proband, and the two variants have not been previously reported. The parents were confirmed as carriers. The two variants were predicted to be pathogenic by in silico tools and were classified as pathogenic/likely pathogenic variants according to the American College of Medical Genetics and Genomics guideline. cDNA TA cloning analysis showed that both splice site variants caused a deletion of exon 5. RT-PCR revealed that the expression of TMEM231 was significantly decreased and immunofluorescence showed that the primary cilium was almost absent in the proband's kidney tissue. Conclusion: We reported the clinical, genetic, molecular and histochemical characterisation of a family affected by MKS. Our findings not only extended the mutation spectrum of the TMEM231 gene, but also revealed for the first time the pathological aetiology of primary cilia in humans and provide a basis for genetic counselling of the parents to their offspring.
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Affiliation(s)
- Qian Zhang
- Henan Provincial Key Laboratory of Genetic Diseases and Functional Genomics, Henan Provincial People’s Hospital, Medical Genetics Institute of Henan Province, People’s Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
- National Health Commission Key Laboratory of Birth Defects Prevention, Henan Key Laboratory of Population Defects Prevention, Zhengzhou, China
| | - Shuya Yang
- People’s Hospital of Henan University, Henan University, Zhengzhou, China
| | - Xin Chen
- Henan Provincial Key Laboratory of Genetic Diseases and Functional Genomics, Henan Provincial People’s Hospital, Medical Genetics Institute of Henan Province, People’s Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
- National Health Commission Key Laboratory of Birth Defects Prevention, Henan Key Laboratory of Population Defects Prevention, Zhengzhou, China
| | - Hongdan Wang
- Henan Provincial Key Laboratory of Genetic Diseases and Functional Genomics, Henan Provincial People’s Hospital, Medical Genetics Institute of Henan Province, People’s Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
- National Health Commission Key Laboratory of Birth Defects Prevention, Henan Key Laboratory of Population Defects Prevention, Zhengzhou, China
| | - Keyan Li
- National Health Commission Key Laboratory of Birth Defects Prevention, Henan Key Laboratory of Population Defects Prevention, Zhengzhou, China
| | - Chaonan Zhang
- National Health Commission Key Laboratory of Birth Defects Prevention, Henan Key Laboratory of Population Defects Prevention, Zhengzhou, China
| | - Shixiu Liao
- Henan Provincial Key Laboratory of Genetic Diseases and Functional Genomics, Henan Provincial People’s Hospital, Medical Genetics Institute of Henan Province, People’s Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
- National Health Commission Key Laboratory of Birth Defects Prevention, Henan Key Laboratory of Population Defects Prevention, Zhengzhou, China
| | - Litao Qin
- Henan Provincial Key Laboratory of Genetic Diseases and Functional Genomics, Henan Provincial People’s Hospital, Medical Genetics Institute of Henan Province, People’s Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
- National Health Commission Key Laboratory of Birth Defects Prevention, Henan Key Laboratory of Population Defects Prevention, Zhengzhou, China
| | - Qiaofang Hou
- Henan Provincial Key Laboratory of Genetic Diseases and Functional Genomics, Henan Provincial People’s Hospital, Medical Genetics Institute of Henan Province, People’s Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
- National Health Commission Key Laboratory of Birth Defects Prevention, Henan Key Laboratory of Population Defects Prevention, Zhengzhou, China
- People’s Hospital of Henan University, Henan University, Zhengzhou, China
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2
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Leggatt GP, Seaby EG, Veighey K, Gast C, Gilbert RD, Ennis S. A Role for Genetic Modifiers in Tubulointerstitial Kidney Diseases. Genes (Basel) 2023; 14:1582. [PMID: 37628633 PMCID: PMC10454709 DOI: 10.3390/genes14081582] [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: 07/17/2023] [Revised: 07/31/2023] [Accepted: 08/01/2023] [Indexed: 08/27/2023] Open
Abstract
With the increased availability of genomic sequencing technologies, the molecular bases for kidney diseases such as nephronophthisis and mitochondrially inherited and autosomal-dominant tubulointerstitial kidney diseases (ADTKD) has become increasingly apparent. These tubulointerstitial kidney diseases (TKD) are monogenic diseases of the tubulointerstitium and result in interstitial fibrosis and tubular atrophy (IF/TA). However, monogenic inheritance alone does not adequately explain the highly variable onset of kidney failure and extra-renal manifestations. Phenotypes vary considerably between individuals harbouring the same pathogenic variant in the same putative monogenic gene, even within families sharing common environmental factors. While the extreme end of the disease spectrum may have dramatic syndromic manifestations typically diagnosed in childhood, many patients present a more subtle phenotype with little to differentiate them from many other common forms of non-proteinuric chronic kidney disease (CKD). This review summarises the expanding repertoire of genes underpinning TKD and their known phenotypic manifestations. Furthermore, we collate the growing evidence for a role of modifier genes and discuss the extent to which these data bridge the historical gap between apparently rare monogenic TKD and polygenic non-proteinuric CKD (excluding polycystic kidney disease).
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Affiliation(s)
- Gary P. Leggatt
- Human Genetics & Genomic Medicine, University of Southampton, Southampton SO16 6YD, UK; (E.G.S.); (K.V.); (C.G.); (R.D.G.); (S.E.)
- Wessex Kidney Centre, Queen Alexandra Hospital, Portsmouth Hospitals NHS Trust, Portsmouth PO6 3LY, UK
- Renal Department, University Hospital Southampton, Southampton SO16 6YD, UK
| | - Eleanor G. Seaby
- Human Genetics & Genomic Medicine, University of Southampton, Southampton SO16 6YD, UK; (E.G.S.); (K.V.); (C.G.); (R.D.G.); (S.E.)
| | - Kristin Veighey
- Human Genetics & Genomic Medicine, University of Southampton, Southampton SO16 6YD, UK; (E.G.S.); (K.V.); (C.G.); (R.D.G.); (S.E.)
- Renal Department, University Hospital Southampton, Southampton SO16 6YD, UK
| | - Christine Gast
- Human Genetics & Genomic Medicine, University of Southampton, Southampton SO16 6YD, UK; (E.G.S.); (K.V.); (C.G.); (R.D.G.); (S.E.)
- Wessex Kidney Centre, Queen Alexandra Hospital, Portsmouth Hospitals NHS Trust, Portsmouth PO6 3LY, UK
| | - Rodney D. Gilbert
- Human Genetics & Genomic Medicine, University of Southampton, Southampton SO16 6YD, UK; (E.G.S.); (K.V.); (C.G.); (R.D.G.); (S.E.)
- Department of Paediatric Nephrology, Southampton Children’s Hospital, University Hospital Southampton NHS Foundation Trust, Southampton SO16 6YD, UK
| | - Sarah Ennis
- Human Genetics & Genomic Medicine, University of Southampton, Southampton SO16 6YD, UK; (E.G.S.); (K.V.); (C.G.); (R.D.G.); (S.E.)
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3
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Mastrorosa FK, Miller DE, Eichler EE. Applications of long-read sequencing to Mendelian genetics. Genome Med 2023; 15:42. [PMID: 37316925 DOI: 10.1186/s13073-023-01194-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 05/18/2023] [Indexed: 06/16/2023] Open
Abstract
Advances in clinical genetic testing, including the introduction of exome sequencing, have uncovered the molecular etiology for many rare and previously unsolved genetic disorders, yet more than half of individuals with a suspected genetic disorder remain unsolved after complete clinical evaluation. A precise genetic diagnosis may guide clinical treatment plans, allow families to make informed care decisions, and permit individuals to participate in N-of-1 trials; thus, there is high interest in developing new tools and techniques to increase the solve rate. Long-read sequencing (LRS) is a promising technology for both increasing the solve rate and decreasing the amount of time required to make a precise genetic diagnosis. Here, we summarize current LRS technologies, give examples of how they have been used to evaluate complex genetic variation and identify missing variants, and discuss future clinical applications of LRS. As costs continue to decrease, LRS will find additional utility in the clinical space fundamentally changing how pathological variants are discovered and eventually acting as a single-data source that can be interrogated multiple times for clinical service.
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Affiliation(s)
| | - Danny E Miller
- Division of Genetic Medicine, Department of Pediatrics, University of Washington and Seattle Children's Hospital, Seattle, WA, 98195, USA
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, 98195, USA
- Brotman Baty Institute for Precision Medicine, University of Washington, Seattle, WA, 98195, USA
| | - Evan E Eichler
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, 98195, USA.
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, 98195, USA.
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4
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Walczak-Sztulpa J, Wawrocka A, Doornbos C, van Beek R, Sowińska-Seidler A, Jamsheer A, Bukowska-Olech E, Latos-Bieleńska A, Grenda R, Bongers EMHF, Schmidts M, Obersztyn E, Krawczyński MR, Oud MM. Identical IFT140 Variants Cause Variable Skeletal Ciliopathy Phenotypes—Challenges for the Accurate Diagnosis. Front Genet 2022; 13:931822. [PMID: 35873489 PMCID: PMC9300986 DOI: 10.3389/fgene.2022.931822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 06/15/2022] [Indexed: 11/13/2022] Open
Abstract
Ciliopathies are rare congenital disorders, caused by defects in the cilium, that cover a broad clinical spectrum. A subgroup of ciliopathies showing significant phenotypic overlap are known as skeletal ciliopathies and include Jeune asphyxiating thoracic dysplasia (JATD), Mainzer-Saldino syndrome (MZSDS), cranioectodermal dysplasia (CED), and short-rib polydactyly (SRP). Ciliopathies are heterogeneous disorders with >187 associated genes, of which some genes are described to cause more than one ciliopathy phenotype. Both the clinical and molecular overlap make accurate diagnosing of these disorders challenging. We describe two unrelated Polish patients presenting with a skeletal ciliopathy who share the same compound heterozygous variants in IFT140 (NM_014,714.4) r.2765_2768del; p.(Tyr923Leufs*28) and exon 27–30 duplication; p.(Tyr1152_Thr1394dup). Apart from overlapping clinical symptoms the patients also show phenotypic differences; patient 1 showed more resemblance to a Mainzer-Saldino syndrome (MZSDS) phenotype, while patient 2 was more similar to the phenotype of cranioectodermal dysplasia (CED). In addition, functional testing in patient-derived fibroblasts revealed a distinct cilium phenotyps for each patient, and strikingly, the cilium phenotype of CED-like patient 2 resembled that of known CED patients. Besides two variants in IFT140, in depth exome analysis of ciliopathy associated genes revealed a likely-pathogenic heterozygous variant in INTU for patient 2 that possibly affects the same IFT-A complex to which IFT140 belongs and thereby could add to the phenotype of patient 2. Taken together, by combining genetic data, functional test results, and clinical findings we were able to accurately diagnose patient 1 with “IFT140-related ciliopathy with MZSDS-like features” and patient 2 with “IFT140-related ciliopathy with CED-like features”. This study emphasizes that identical variants in one ciliopathy associated gene can lead to a variable ciliopathy phenotype and that an in depth and integrated analysis of clinical, molecular and functional data is necessary to accurately diagnose ciliopathy patients.
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Affiliation(s)
| | - Anna Wawrocka
- Department of Medical Genetics, Poznan University of Medical Sciences, Poznan, Poland
| | - Cenna Doornbos
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, Netherlands
| | - Ronald van Beek
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, Netherlands
| | - Anna Sowińska-Seidler
- Department of Medical Genetics, Poznan University of Medical Sciences, Poznan, Poland
| | - Aleksander Jamsheer
- Department of Medical Genetics, Poznan University of Medical Sciences, Poznan, Poland
- Centers for Medical Genetics, Poznan, Poland
| | | | - Anna Latos-Bieleńska
- Department of Medical Genetics, Poznan University of Medical Sciences, Poznan, Poland
| | - Ryszard Grenda
- Department of Nephrology, Kidney Transplantation and Hypertension, The Children’s Memorial Health Institute, Warsaw, Poland
| | | | - Miriam Schmidts
- Center for Pediatrics and Adolescent Medicine, University Hospital Freiburg, Freiburg University Faculty of Medicine, Freiburg, Germany
- CIBSS—Centre for Integrative Biological Signalling Studies, Freiburg University, Freiburg, Germany
| | - Ewa Obersztyn
- Department of Medical Genetics, Institute of Mother and Child, Warsaw, Poland
| | - Maciej R. Krawczyński
- Department of Medical Genetics, Poznan University of Medical Sciences, Poznan, Poland
- Centers for Medical Genetics, Poznan, Poland
| | - Machteld M. Oud
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, Netherlands
- *Correspondence: Machteld M. Oud,
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5
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Van De Weghe JC, Gomez A, Doherty D. The Joubert-Meckel-Nephronophthisis Spectrum of Ciliopathies. Annu Rev Genomics Hum Genet 2022; 23:301-329. [PMID: 35655331 DOI: 10.1146/annurev-genom-121321-093528] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Joubert syndrome (JS), Meckel syndrome (MKS), and nephronophthisis (NPH) ciliopathy spectrum could be the poster child for advances and challenges in Mendelian human genetics over the past half century. Progress in understanding these conditions illustrates many core concepts of human genetics. The JS phenotype alone is caused by pathogenic variants in more than 40 genes; remarkably, all of the associated proteins function in and around the primary cilium. Primary cilia are near-ubiquitous, microtubule-based organelles that play crucial roles in development and homeostasis. Protruding from the cell, these cellular antennae sense diverse signals and mediate Hedgehog and other critical signaling pathways. Ciliary dysfunction causes many human conditions termed ciliopathies, which range from multiple congenital malformations to adult-onset single-organ failure. Research on the genetics of the JS-MKS-NPH spectrum has spurred extensive functional work exploring the broadly important role of primary cilia in health and disease. This functional work promises to illuminate the mechanisms underlying JS-MKS-NPH in humans, identify therapeutic targets across genetic causes, and generate future precision treatments. Expected final online publication date for the Annual Review of Genomics and Human Genetics, Volume 23 is October 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
| | - Arianna Gomez
- Department of Pediatrics, University of Washington, Seattle, Washington, USA; .,Molecular Medicine and Mechanisms of Disease Program, Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, USA;
| | - Dan Doherty
- Department of Pediatrics, University of Washington, Seattle, Washington, USA; .,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA;
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6
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Gana S, Serpieri V, Valente EM. Genotype-phenotype correlates in Joubert syndrome: A review. AMERICAN JOURNAL OF MEDICAL GENETICS. PART C, SEMINARS IN MEDICAL GENETICS 2022; 190:72-88. [PMID: 35238134 PMCID: PMC9314610 DOI: 10.1002/ajmg.c.31963] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 02/04/2022] [Accepted: 02/15/2022] [Indexed: 01/20/2023]
Abstract
Joubert syndrome (JS) is a genetically heterogeneous primary ciliopathy characterized by a pathognomonic cerebellar and brainstem malformation, the “molar tooth sign,” and variable organ involvement. Over 40 causative genes have been identified to date, explaining up to 94% of cases. To date, gene‐phenotype correlates have been delineated only for a handful of genes, directly translating into improved counseling and clinical care. For instance, JS individuals harboring pathogenic variants in TMEM67 have a significantly higher risk of liver fibrosis, while pathogenic variants in NPHP1, RPGRIP1L, and TMEM237 are frequently associated to JS with renal involvement, requiring a closer monitoring of liver parameters, or renal functioning. On the other hand, individuals with causal variants in the CEP290 or AHI1 need a closer surveillance for retinal dystrophy and, in case of CEP290, also for chronic kidney disease. These examples highlight how an accurate description of the range of clinical symptoms associated with defects in each causative gene, including the rare ones, would better address prognosis and help guiding a personalized management. This review proposes to address this issue by assessing the available literature, to confirm known, as well as to propose rare gene‐phenotype correlates in JS.
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Affiliation(s)
- Simone Gana
- Neurogenetics Research Center, IRCCS Mondino Foundation, Pavia, Italy
| | | | - Enza Maria Valente
- Neurogenetics Research Center, IRCCS Mondino Foundation, Pavia, Italy.,Department of Molecular Medicine, University of Pavia, Pavia, Italy
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7
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Laurent S, Gehrig C, Nouspikel T, Amr SS, Oza A, Murphy E, Vannier A, Béna FS, Carminho-Rodrigues MT, Blouin JL, Cao Van H, Abramowicz M, Paoloni-Giacobino A, Guipponi M. Molecular characterization of pathogenic OTOA gene conversions in hearing loss patients. Hum Mutat 2021; 42:373-377. [PMID: 33492714 DOI: 10.1002/humu.24167] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 12/02/2020] [Accepted: 12/16/2020] [Indexed: 11/11/2022]
Abstract
Bi-allelic loss-of-function variants of OTOA are a well-known cause of moderate-to-severe hearing loss. Whereas non-allelic homologous recombination-mediated deletions of the gene are well known, gene conversions to pseudogene OTOAP1 have been reported in the literature but never fully described nor their pathogenicity assessed. Here, we report two unrelated patients with moderate hearing-loss, who were compound heterozygotes for a converted allele and a deletion of OTOA. The conversions were initially detected through sequencing depths anomalies at the OTOA locus after exome sequencing, then confirmed with long range polymerase chain reactions. Both conversions lead to loss-of-function by introducing a premature stop codon in exon 22 (p.Glu787*). Using genomic alignments and long read nanopore sequencing, we found that the two probands carry stretches of converted DNA of widely different lengths (at least 9 kbp and around 900 bp, respectively).
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Affiliation(s)
- Sacha Laurent
- Department of Diagnostic, Genetic Medicine Unit, University Hospitals of Geneva, Geneva, Switzerland
| | - Corinne Gehrig
- Department of Diagnostic, Genetic Medicine Unit, University Hospitals of Geneva, Geneva, Switzerland
| | - Thierry Nouspikel
- Department of Diagnostic, Genetic Medicine Unit, University Hospitals of Geneva, Geneva, Switzerland
| | - Sami S Amr
- Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine, Cambridge, Massachusetts, USA
| | - Andrea Oza
- Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine, Cambridge, Massachusetts, USA
| | - Elissa Murphy
- Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine, Cambridge, Massachusetts, USA
| | - Anne Vannier
- Department of Diagnostic, Genetic Medicine Unit, University Hospitals of Geneva, Geneva, Switzerland
| | - Frédérique Sloan Béna
- Department of Diagnostic, Genetic Medicine Unit, University Hospitals of Geneva, Geneva, Switzerland.,Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | | | - Jean-Louis Blouin
- Department of Diagnostic, Genetic Medicine Unit, University Hospitals of Geneva, Geneva, Switzerland.,Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Hélène Cao Van
- Department of Otorhinolaryngology, Head and Neck Surgery, Pediatric Otolaryngology Unit, University Hospitals of Geneva, Geneva, Switzerland
| | - Marc Abramowicz
- Department of Diagnostic, Genetic Medicine Unit, University Hospitals of Geneva, Geneva, Switzerland.,Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Ariane Paoloni-Giacobino
- Department of Diagnostic, Genetic Medicine Unit, University Hospitals of Geneva, Geneva, Switzerland.,Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Michel Guipponi
- Department of Diagnostic, Genetic Medicine Unit, University Hospitals of Geneva, Geneva, Switzerland.,Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
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8
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Wang T, Liu YX, Luo FM, Dong Y, Li YL, Fan LL. A Novel Homozygous Variant of TMEM231 in a Case With Hypoplasia of the Cerebellar Vermis and Polydactyly. Front Pediatr 2021; 9:774575. [PMID: 34912761 PMCID: PMC8666876 DOI: 10.3389/fped.2021.774575] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 10/22/2021] [Indexed: 12/25/2022] Open
Abstract
Background: Transmembrane protein 231 (TMEM231) is a component of the B9 complex that participates in the formation of the diffusion barrier between the cilia and plasma membrane. Mutations in TMEM231 gene may contribute to the Joubert syndrome (JBTS) or Meckel-Gruber syndrome (MKS). However, reports on JBTS or MKS caused by TMEM231 mutations are comparatively rare. Method: We describe a Chinese fetus with unexplained hypoplasia of the cerebellar vermis and polydactyly, detected by ultrasound imaging. The fetus was primarily diagnosed with JBTS/MKS. The parents of this fetus were non-consanguineous and healthy. Whole-exome sequencing (WES) and bioinformatics strategies were employed to explore the genetic lesion of this family. Results: An unknown missense variant (c.19C>T;p.R7W) of TMEM231 gene was detected. The variant was predicted as pathogenic and was absent in our 200 healthy controls. Conclusion: WES was employed to explore the genetic lesion of a fetus with unexplained hypoplasia of the cerebellar vermis and polydactyly. A novel variant in TMEM231 gene was identified. Our study not only provided data for genetic counseling and prenatal diagnosis to this family but also broadened the spectrum of TMEM231 mutations.
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Affiliation(s)
- Tao Wang
- Departments of Reproductive Genetics, HeBei General Hospital, ShiJiaZhuang, China
| | - Yu-Xing Liu
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, China
| | - Fang-Mei Luo
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, China
| | - Yi Dong
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, China
| | - Ya-Li Li
- Departments of Reproductive Genetics, HeBei General Hospital, ShiJiaZhuang, China
| | - Liang-Liang Fan
- Departments of Reproductive Genetics, HeBei General Hospital, ShiJiaZhuang, China.,Department of Cell Biology, School of Life Sciences, Central South University, Changsha, China.,Hunan Key Laboratory of Animal Models for Human Disease, School of Life Sciences, Central South University, Changsha, China
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9
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Watson CM, Dean P, Camm N, Bates J, Carr IM, Gardiner CA, Bonthron DT. Long-read nanopore sequencing resolves a TMEM231 gene conversion event causing Meckel-Gruber syndrome. Hum Mutat 2019; 41:525-531. [PMID: 31663672 DOI: 10.1002/humu.23940] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 09/12/2019] [Accepted: 10/28/2019] [Indexed: 12/30/2022]
Abstract
The diagnostic deployment of massively parallel short-read next-generation sequencing (NGS) has greatly improved genetic test availability, speed, and diagnostic yield, particularly for rare inherited disorders. Nonetheless, diagnostic approaches based on short-read sequencing have a poor ability to accurately detect gene conversion events. We report on the genetic analysis of a family in which 3 fetuses had clinical features consistent with the autosomal recessive disorder Meckel-Gruber syndrome (MKS). Targeted NGS of 29 known MKS-associated genes revealed a heterozygous TMEM231 splice donor variant c.929+1A>G. Comparative read-depth analysis, performed to identify a second pathogenic allele, revealed an apparent heterozygous deletion of TMEM231 exon 4. To verify this result we performed single-molecule long-read sequencing of a long-range polymerase chain reaction product spanning this locus. We identified four missense variants that were absent from the short-read dataset due to the preferential mapping of variant-containing reads to a downstream TMEM231 pseudogene. Consistent with the parental segregation analysis, we demonstrate that the single-molecule long reads could be used to show that the variants are arranged in trans. Our experience shows that robust validation of apparent dosage variants remains essential to avoid the pitfalls of short-read sequencing and that new third-generation long-read sequencing technologies can already aid routine clinical care.
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Affiliation(s)
- Christopher M Watson
- Yorkshire Regional Genetics Service, St. James's University Hospital, Leeds, UK.,Leeds Institute of Medical Research, St. James's University Hospital, University of Leeds, Leeds, UK
| | - Philip Dean
- Yorkshire Regional Genetics Service, St. James's University Hospital, Leeds, UK
| | - Nick Camm
- Yorkshire Regional Genetics Service, St. James's University Hospital, Leeds, UK
| | - Jennifer Bates
- Yorkshire Regional Genetics Service, St. James's University Hospital, Leeds, UK
| | - Ian M Carr
- Leeds Institute of Medical Research, St. James's University Hospital, University of Leeds, Leeds, UK
| | - Carol A Gardiner
- West of Scotland Regional Genetics Services, Queen Elizabeth University Hospital, Glasgow, UK
| | - David T Bonthron
- Yorkshire Regional Genetics Service, St. James's University Hospital, Leeds, UK.,Leeds Institute of Medical Research, St. James's University Hospital, University of Leeds, Leeds, UK
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10
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Parisi MA. The molecular genetics of Joubert syndrome and related ciliopathies: The challenges of genetic and phenotypic heterogeneity. ACTA ACUST UNITED AC 2019; 4:25-49. [PMID: 31763177 PMCID: PMC6864416 DOI: 10.3233/trd-190041] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Joubert syndrome (JS; MIM PS213300) is a rare, typically autosomal recessive disorder characterized by cerebellar vermis hypoplasia and a distinctive malformation of the cerebellum and brainstem identified as the “molar tooth sign” on brain MRI. Other universal features include hypotonia with later ataxia and intellectual disability/developmental delay, with additional features consisting of oculomotor apraxia and abnormal respiratory pattern. Notably, other, more variable features include renal cystic disease, typically nephronophthisis, retinal dystrophy, and congenital hepatic fibrosis; skeletal changes such as polydactyly and findings consistent with short-rib skeletal dysplasias are also seen in many subjects. These pleiotropic features are typical of a number of disorders of the primary cilium, and make the identification of causal genes challenging given the significant overlap between JS and other ciliopathy conditions such as nephronophthisis and Meckel, Bardet-Biedl, and COACH syndromes. This review will describe the features of JS, characterize the 35 known genes associated with the condition, and describe some of the genetic conundrums of JS, such as the heterogeneity of founder effects, lack of genotype-phenotype correlations, and role of genetic modifiers. Finally, aspects of JS and related ciliopathies that may pave the way for development of therapeutic interventions, including gene therapy, will be described.
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Affiliation(s)
- Melissa A Parisi
- Chief, Intellectual & Developmental Disabilities Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD, USA
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Nicolas-Jilwan M, Al-Ahmari AN, Alowain MA, Altuhaini KS, Alshail EA. Tectocerebellar dysraphia with occipital encephalocele: a phenotypic variant of the TMEM231 gene mutation induced Joubert syndrome. Childs Nerv Syst 2019; 35:1257-1261. [PMID: 30617574 DOI: 10.1007/s00381-019-04048-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 01/02/2019] [Indexed: 11/28/2022]
Abstract
There are few reported cases of tectocerebellar dysraphia with occipital encephalocele (TCD-OE) in the literature. This malformation was first described by Padget and Lindburg in 1972 and consists of an occipital encephalocele, a cerebellar midline defect, inverted cerebellum, and deformity of the tectum. Occurrence is believed to be sporadic with a male predominance and a usually poor prognosis. We report a patient with brain MRI findings compatible with tectocerebellar dysraphia and occipital encephalocele. Additional features consistent with Joubert syndrome including deepened interpeduncular fossa, as well as elongated, thickened, and anteroposteriorly oriented superior cerebellar peduncles, were noted. The patient's evaluation also revealed a homozygous mutation of the TMEM231 gene, known to cause Meckel-Gruber and Joubert syndromes. Our case represents the first reported genetic confirmation that tectocerebellar dysraphia with occipital encephalocele is not a distinct nosological entity but likely a phenotypic variation of Joubert syndrome.
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Affiliation(s)
- Manal Nicolas-Jilwan
- Division of Neuroradiology, Department of Radiology, King Faisal Specialist Hospital and Research Centre, Al Zahrawi Street, Riyadh, 11211, Saudi Arabia.
| | - Ahmed Nasser Al-Ahmari
- Division of Neurosurgery, Department of Neurosciences, King Faisal Specialist Hospital and Research Centre, Al Zahrawi Street, Riyadh, 11211, Saudi Arabia
| | - Mohammed Abdulaziz Alowain
- Department of Medical Genetics, King Faisal Specialist Hospital and Research Centre, Al Zahrawi Street, Riyadh, 11211, Saudi Arabia
| | | | - Essam Abdulaziz Alshail
- Division of Neurosurgery, Department of Neurosciences, King Faisal Specialist Hospital and Research Centre, Al Zahrawi Street, Riyadh, 11211, Saudi Arabia
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Phelps IG, Dempsey JC, Grout ME, Isabella CR, Tully HM, Doherty D, Bachmann-Gagescu R. Interpreting the clinical significance of combined variants in multiple recessive disease genes: systematic investigation of Joubert syndrome yields little support for oligogenicity. Genet Med 2018; 20:223-233. [PMID: 28771248 PMCID: PMC5797514 DOI: 10.1038/gim.2017.94] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 05/19/2017] [Indexed: 01/11/2023] Open
Abstract
PurposeNext-generation sequencing (NGS) often identifies multiple rare predicted-deleterious variants (RDVs) in different genes associated with a recessive disorder in a given patient. Such variants have been proposed to contribute to digenicity/oligogenicity or "triallelism" or to act as genetic modifiers.MethodsUsing the recessive ciliopathy Joubert syndrome (JBTS) as a model, we investigated these possibilities systematically, relying on NGS of known JBTS genes in a large JBTS and two control cohorts.Results65% of affected individuals had a recessive genetic cause, while 4.9% were candidates for di-/oligogenicity, harboring heterozygous RDVs in two or more genes, compared with 4.2-8% in controls (P = 0.66-0.21). Based on Exome Aggregation Consortium (ExAC) allele frequencies, the probability of cumulating RDVs in any two JBTS genes is 9.3%. We found no support for triallelism, as no unaffected siblings carried the same biallelic RDVs as their affected relative. Sixty percent of individuals sharing identical causal RDVs displayed phenotypic discordance. Although 38% of affected individuals harbored RDVs in addition to the causal mutations, their presence did not correlate with phenotypic severity.ConclusionOur data offer little support for triallelism or digenicity/oligogenicity as clinically relevant inheritance modes in JBTS. While phenotypic discordance supports the existence of genetic modifiers, identifying clinically relevant modifiers remains challenging.
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Affiliation(s)
- Ian G. Phelps
- Department of Pediatrics, University of Washington, Seattle, WA, USA
| | | | - Megan E. Grout
- Department of Pediatrics, University of Washington, Seattle, WA, USA
| | | | - Hannah M. Tully
- Department of Neurology, University of Washington, Seattle, Washington
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, Washington
| | - Dan Doherty
- Department of Pediatrics, University of Washington, Seattle, WA, USA
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, Washington
| | - Ruxandra Bachmann-Gagescu
- Institute of Medical Genetics, University of Zurich, Switzerland
- Institute of Molecular Life Sciences, University of Zurich, Switzerland
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Fleming LR, Doherty DA, Parisi MA, Glass IA, Bryant J, Fischer R, Turkbey B, Choyke P, Daryanani K, Vemulapalli M, Mullikin JC, Malicdan MC, Vilboux T, Sayer JA, Gahl WA, Gunay-Aygun M. Prospective Evaluation of Kidney Disease in Joubert Syndrome. Clin J Am Soc Nephrol 2017; 12:1962-1973. [PMID: 29146704 PMCID: PMC5718273 DOI: 10.2215/cjn.05660517] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 09/18/2017] [Indexed: 01/30/2023]
Abstract
BACKGROUND AND OBJECTIVES Joubert syndrome is a genetically heterogeneous ciliopathy associated with >30 genes. The characteristics of kidney disease and genotype-phenotype correlations have not been evaluated in a large cohort at a single center. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We evaluated 97 individuals with Joubert syndrome at the National Institutes of Health Clinical Center using abdominal ultrasonography, blood and urine chemistries, and DNA sequencing. RESULTS Patients were ages 0.6-36 years old (mean of 9.0±7.6 years old); 41 were female. Mutations were identified in 19 genes in 92 patients; two thirds of the mutations resided in six genes: TMEM67, C5orf42, CC2D2A, CEP290, AHI1, and KIAA0586. Kidney disease was detected in 30%, most commonly in association with the following genes: CEP290 (six of six), TMEM67 (11 of 22), and AHI1 (three of six). No kidney disease was identified in patients with mutations in C5orf42 (zero of 15) or KIAA0586 (zero of six). Prenatal ultrasonography of kidneys was normal in 72% of patients with kidney disease. Specific types of kidney disease included nephronophthisis (31%), an overlap phenotype of autosomal recessive polycystic kidney disease/nephronophthisis (35%), unilateral multicystic dysplastic kidney (10%), and indeterminate-type cystic kidney disease (24%). Early-onset hypertension occurred in 24% of patients with kidney disease. Age at ESRD (n=13) ranged from 6 to 24 years old (mean of 11.3±4.8 years old). CONCLUSIONS Kidney disease occurs in up to one third of patients with Joubert syndrome, most commonly in those with mutations in CEP290, TMEM67, and AHI1. Patients with mutations in C5orf42 or KIAA0586 are less likely to develop kidney disease. Prenatal ultrasonography is a poor predictor of kidney involvement in Joubert syndrome. Unilateral multicystic dysplastic kidney and autosomal recessive polycystic kidney disease-like enlarged kidneys with early-onset hypertension can be part of the Joubert syndrome kidney phenotype.
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MESH Headings
- Abnormalities, Multiple/diagnostic imaging
- Abnormalities, Multiple/genetics
- Abnormalities, Multiple/metabolism
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Vesicular Transport
- Adolescent
- Adult
- Age of Onset
- Antigens, Neoplasm/genetics
- Cell Cycle Proteins/genetics
- Cerebellum/abnormalities
- Cerebellum/diagnostic imaging
- Cerebellum/metabolism
- Child
- Child, Preschool
- Cytoskeletal Proteins
- Eye Abnormalities/complications
- Eye Abnormalities/diagnostic imaging
- Eye Abnormalities/genetics
- Eye Abnormalities/metabolism
- Female
- Genotype
- Humans
- Infant
- Kidney Diseases, Cystic/complications
- Kidney Diseases, Cystic/congenital
- Kidney Diseases, Cystic/diagnostic imaging
- Kidney Diseases, Cystic/genetics
- Kidney Diseases, Cystic/metabolism
- Kidney Failure, Chronic/etiology
- Kidney Failure, Chronic/genetics
- Magnetic Resonance Imaging
- Male
- Membrane Proteins/genetics
- Multicystic Dysplastic Kidney/complications
- Multicystic Dysplastic Kidney/diagnostic imaging
- Multicystic Dysplastic Kidney/genetics
- Mutation
- Neoplasm Proteins/genetics
- Phenotype
- Polycystic Kidney, Autosomal Recessive/complications
- Polycystic Kidney, Autosomal Recessive/diagnostic imaging
- Polycystic Kidney, Autosomal Recessive/genetics
- Prospective Studies
- Proteins/genetics
- Retina/abnormalities
- Retina/diagnostic imaging
- Retina/metabolism
- Ultrasonography, Prenatal
- Young Adult
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Affiliation(s)
- Leah R Fleming
- Due to the number of contributing authors, the affiliations are provided in the Supplemental Material
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Abstract
Motile and non-motile (primary) cilia are nearly ubiquitous cellular organelles. The dysfunction of cilia causes diseases known as ciliopathies. The number of reported ciliopathies (currently 35) is increasing, as is the number of established (187) and candidate (241) ciliopathy-associated genes. The characterization of ciliopathy-associated proteins and phenotypes has improved our knowledge of ciliary functions. In particular, investigating ciliopathies has helped us to understand the molecular mechanisms by which the cilium-associated basal body functions in early ciliogenesis, as well as how the transition zone functions in ciliary gating, and how intraflagellar transport enables cargo trafficking and signalling. Both basic biological and clinical studies are uncovering novel ciliopathies and the ciliary proteins involved. The assignment of these proteins to different ciliary structures, processes and ciliopathy subclasses (first order and second order) provides insights into how this versatile organelle is built, compartmentalized and functions in diverse ways that are essential for human health.
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