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Li C, Zhang R, Pan F, Xin Q, Shi X, Guo W, Qiao D, Wang Z, Zhang Y, Liu X, Zhang Y, Shao L. Functional analysis of the CTNS gene exonic variants predicted to affect splicing. Clin Genet 2024; 105:323-328. [PMID: 38009794 DOI: 10.1111/cge.14460] [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: 09/01/2023] [Revised: 10/26/2023] [Accepted: 11/15/2023] [Indexed: 11/29/2023]
Abstract
Cystinosis is a severe, monogenic systemic disease caused by variants in CTNS gene. Currently, there is growing evidence that exonic variants in many diseases can affect pre-mRNA splicing. The impact of CTNS gene exonic variants on splicing regulation may be underestimated due to the lack of routine studies at the RNA level. Here, we analyzed 59 exonic variants in the CTNS gene using bioinformatics tools and identified candidate variants that may induce splicing alterations by minigene assays. We identified six exonic variants that induce splicing alterations by disrupting the ratio of exonic splicing enhancers/exonic splicing silencers (ESEs/ESSs) or by interfering with the recognition of classical splice sites, or both. Our results help in the correct molecular characterization of variants in cystinosis and inform emerging therapies. Furthermore, our work suggests that the combination of in silico and in vitro assays facilitates to assess the effects of DNA variants driving rare genetic diseases on splicing regulation and will enhance the clinical utility of variant functional annotation.
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Affiliation(s)
- Changying Li
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Ruixiao Zhang
- Department of Emergency, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Fengjiao Pan
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Qing Xin
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Xiaomeng Shi
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Wencong Guo
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Dan Qiao
- Department of Nephrology, Dalian Medical University, Dalian, China
| | - Zhi Wang
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Yiyin Zhang
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Xuyan Liu
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Yan Zhang
- Department of Nephrology, Weifang Medical University, Weifang, China
| | - Leping Shao
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
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Zhang X, Zhi X, Wang X, Dong Y, Shu J, Wang W, Cai C. Identification of a Splicing Variant c.3813-3A>G in NPHP3 by Reanalysis of Whole Exome Sequencing in a Chinese Boy with Nephronophthisis. Nephron Clin Pract 2023; 147:572-582. [PMID: 36878198 DOI: 10.1159/000529472] [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: 07/31/2022] [Accepted: 01/02/2023] [Indexed: 03/08/2023] Open
Abstract
Nephronophthisis is an autosomal recessive cystic kidney disease characterized by tubular injury and commonly results in kidney failure. We reported a case of 4-year-old Chinese boy presented with severe anemia, kidney, and liver dysfunction. Whole exome sequencing (WES) was performed to identify the candidate variant with a negative result initially. After complete collection of clinical information, reanalysis of WES identified a homozygous NPHP3 variant c.3813-3A>G (NM_153240.4). The effect on mRNA splicing of the intronic variant was predicted through software (three in silico splice tools). Furthermore, in vitro minigene assay was conducted to validate the predicted deleterious effects of the intronic variant. All of the splice prediction programs and minigene assay indicated that the variant had an impact on the normal splicing pattern of NPHP3. Our study confirmed the effect of the c.3813-3A>G variant on NPHP3 splicing in vitro, which gives additional evidence for the clinical significance of the variant and provides a basis for genetic diagnosis of nephronophthisis 3. In addition, we think that it is essential to reanalyze WES data after the complete clinical information collection to avoid missing some important candidate variants.
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Affiliation(s)
- Xinjie Zhang
- Tianjin Children's Hospital (Children's Hospital of Tianjin University), Tianjin, China
- Tianjin Pediatric Research Institute, Tianjin, China
- Tianjin Key Laboratory of Birth Defects for Prevention and Treatment, Tianjin, China
| | - Xiufang Zhi
- Graduate College, Tianjin Medical University, Tianjin, China
| | - Xin Wang
- Tianjin Children's Hospital (Children's Hospital of Tianjin University), Tianjin, China
- Department of Nephrology, Tianjin Children's Hospital, Tianjin, China
| | - Yan Dong
- Graduate College, Tianjin Medical University, Tianjin, China
| | - Jianbo Shu
- Tianjin Children's Hospital (Children's Hospital of Tianjin University), Tianjin, China
- Tianjin Pediatric Research Institute, Tianjin, China
- Tianjin Key Laboratory of Birth Defects for Prevention and Treatment, Tianjin, China
| | - Wenhong Wang
- Tianjin Children's Hospital (Children's Hospital of Tianjin University), Tianjin, China
- Department of Nephrology, Tianjin Children's Hospital, Tianjin, China
| | - Chunquan Cai
- Tianjin Children's Hospital (Children's Hospital of Tianjin University), Tianjin, China
- Tianjin Pediatric Research Institute, Tianjin, China
- Tianjin Key Laboratory of Birth Defects for Prevention and Treatment, Tianjin, China
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3
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Bergougnoux A, Billet A, Ka C, Heller M, Degrugillier F, Vuillaume ML, Thoreau V, Sasorith S, Bareil C, Thèze C, Ferec C, Gac GL, Bienvenu T, Bieth E, Gaston V, Lalau G, Pagin A, Malinge MC, Dufernez F, Lemonnier L, Koenig M, Fergelot P, Claustres M, Taulan-Cadars M, Kitzis A, Reboul MP, Becq F, Fanen P, Mekki C, Audrezet MP, Girodon E, Raynal C. The multi-faceted nature of 15 CFTR exonic variations: Impact on their functional classification and perspectives for therapy. J Cyst Fibros 2022:S1569-1993(22)01423-0. [PMID: 36567205 DOI: 10.1016/j.jcf.2022.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 09/30/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022]
Abstract
BACKGROUND The majority of variants of unknown clinical significance (VUCS) in the CFTR gene are missense variants. While change on the CFTR protein structure or function is often suspected, impact on splicing may be neglected. Such undetected splicing default of variants may complicate the interpretation of genetic analyses and the use of an appropriate pharmacotherapy. METHODS We selected 15 variants suspected to impact CFTR splicing after in silico predictions on 319 missense variants (214 VUCS), reported in the CFTR-France database. Six specialized laboratories assessed the impact of nucleotide substitutions on splicing (minigenes), mRNA expression levels (quantitative PCR), synthesis and maturation (western blot), cellular localization (immunofluorescence) and channel function (patch clamp) of the CFTR protein. We also studied maturation and function of the truncated protein, consecutive to in-frame aberrant splicing, on additional plasmid constructs. RESULTS Six of the 15 variants had a major impact on CFTR splicing by in-frame (n = 3) or out-of-frame (n = 3) exon skipping. We reclassified variants into: splicing variants; variants causing a splicing defect and the impairment of CFTR folding and/or function related to the amino acid substitution; deleterious missense variants that impair CFTR folding and/or function; and variants with no consequence on the different processes tested. CONCLUSION The 15 variants have been reclassified by our comprehensive approach of in vitro experiments that should be used to properly interpret very rare exonic variants of the CFTR gene. Targeted therapies may thus be adapted to the molecular defects regarding the results of laboratory experiments.
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Affiliation(s)
- A Bergougnoux
- Génétique Moléculaire, CHU Montpellier, Montpellier, France; PhyMedExp, INSERM, CNRS UMR, Montpellier, France; Université de Montpellier, Montpellier, France
| | - A Billet
- Laboratoire STIM, Université de Poitiers, Poitiers, France
| | - C Ka
- Service de génétique moléculaire, CHRU Brest, Brest, France; Université de Brest, Inserm, UMR 1078, GGB, Brest, France
| | - M Heller
- Service de Médecine Génomique des Maladies de Système et d'Organe, APHP Centre - Université de Paris, Hôpital Cochin, Paris, France
| | - F Degrugillier
- Université Paris-Est Créteil, INSERM, IMRB, Créteil F-94010, France
| | - M-L Vuillaume
- Génétique Moléculaire, CHU Bordeaux, Bordeaux, France
| | - V Thoreau
- Laboratoire NEUVACOD-3808, Université de Poitiers, Poitiers, France
| | - S Sasorith
- Génétique Moléculaire, CHU Montpellier, Montpellier, France; PhyMedExp, INSERM, CNRS UMR, Montpellier, France
| | - C Bareil
- Génétique Moléculaire, CHU Montpellier, Montpellier, France
| | - C Thèze
- Génétique Moléculaire, CHU Montpellier, Montpellier, France
| | - C Ferec
- Université de Brest, Inserm, UMR 1078, GGB, Brest, France
| | - G Le Gac
- Service de génétique moléculaire, CHRU Brest, Brest, France; Université de Brest, Inserm, UMR 1078, GGB, Brest, France
| | - T Bienvenu
- Service de Médecine Génomique des Maladies de Système et d'Organe, APHP Centre - Université de Paris, Hôpital Cochin, Paris, France
| | - E Bieth
- Génétique Médicale, CHU Toulouse, Toulouse, France
| | - V Gaston
- Génétique Médicale, CHU Toulouse, Toulouse, France
| | - G Lalau
- Biochimie et Biologie Moléculaire, CHU Lille, Lille, France
| | - A Pagin
- Biochimie et Biologie Moléculaire, CHU Lille, Lille, France
| | - M-C Malinge
- Biochimie et Génétique, CHU Angers, Angers, France
| | - F Dufernez
- Génétique, CHU Poitiers, Poitiers, France
| | - L Lemonnier
- Association Vaincre la Mucoviscidose, Paris, France
| | - M Koenig
- Génétique Moléculaire, CHU Montpellier, Montpellier, France; PhyMedExp, INSERM, CNRS UMR, Montpellier, France; Université de Montpellier, Montpellier, France
| | - P Fergelot
- MRGM, INSERM UMR 1211 Université de Bordeaux, Bordeaux, France
| | - M Claustres
- Université de Montpellier, Montpellier, France
| | - M Taulan-Cadars
- PhyMedExp, INSERM, CNRS UMR, Montpellier, France; Université de Montpellier, Montpellier, France
| | - A Kitzis
- Génétique, CHU Poitiers, Poitiers, France
| | - M-P Reboul
- Génétique Moléculaire, CHU Bordeaux, Bordeaux, France
| | - F Becq
- Laboratoire STIM, Université de Poitiers, Poitiers, France
| | - P Fanen
- AP-HP, Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, Hôpital Henri Mondor, Créteil F-94010, France
| | - C Mekki
- AP-HP, Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, Hôpital Henri Mondor, Créteil F-94010, France
| | - M-P Audrezet
- Service de génétique moléculaire, CHRU Brest, Brest, France; Université de Brest, Inserm, UMR 1078, GGB, Brest, France
| | - E Girodon
- Service de Médecine Génomique des Maladies de Système et d'Organe, APHP Centre - Université de Paris, Hôpital Cochin, Paris, France; INSERM U1151, Institut Necker Enfants Malades, Université de Paris, Paris, France
| | - C Raynal
- Génétique Moléculaire, CHU Montpellier, Montpellier, France; PhyMedExp, INSERM, CNRS UMR, Montpellier, France.
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