1
|
Sun W, Xiong D, Ouyang J, Xiao X, Jiang Y, Wang Y, Li S, Xie Z, Wang J, Tang Z, Zhang Q. Altered chromatin topologies caused by balanced chromosomal translocation lead to central iris hypoplasia. Nat Commun 2024; 15:5048. [PMID: 38871723 DOI: 10.1038/s41467-024-49376-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 06/04/2024] [Indexed: 06/15/2024] Open
Abstract
Despite the advent of genomic sequencing, molecular diagnosis remains unsolved in approximately half of patients with Mendelian disorders, largely due to unclarified functions of noncoding regions and the difficulty in identifying complex structural variations. In this study, we map a unique form of central iris hypoplasia in a large family to 6q15-q23.3 and 18p11.31-q12.1 using a genome-wide linkage scan. Long-read sequencing reveals a balanced translocation t(6;18)(q22.31;p11.22) with intergenic breakpoints. By performing Hi-C on induced pluripotent stem cells from a patient, we identify two chromatin topologically associating domains spanning across the breakpoints. These alterations lead the ectopic chromatin interactions between APCDD1 on chromosome 18 and enhancers on chromosome 6, resulting in upregulation of APCDD1. Notably, APCDD1 is specifically localized in the iris of human eyes. Our findings demonstrate that noncoding structural variations can lead to Mendelian diseases by disrupting the 3D genome structure and resulting in altered gene expression.
Collapse
Affiliation(s)
- Wenmin Sun
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Dan Xiong
- Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Jiamin Ouyang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Xueshan Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Yi Jiang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Yingwei Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Shiqiang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Ziying Xie
- Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Junwen Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Zhonghui Tang
- Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China.
| |
Collapse
|
2
|
Barbitoff YA, Ushakov MO, Lazareva TE, Nasykhova YA, Glotov AS, Predeus AV. Bioinformatics of germline variant discovery for rare disease diagnostics: current approaches and remaining challenges. Brief Bioinform 2024; 25:bbad508. [PMID: 38271481 PMCID: PMC10810331 DOI: 10.1093/bib/bbad508] [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: 08/09/2023] [Revised: 11/18/2023] [Accepted: 12/12/2023] [Indexed: 01/27/2024] Open
Abstract
Next-generation sequencing (NGS) has revolutionized the field of rare disease diagnostics. Whole exome and whole genome sequencing are now routinely used for diagnostic purposes; however, the overall diagnosis rate remains lower than expected. In this work, we review current approaches used for calling and interpretation of germline genetic variants in the human genome, and discuss the most important challenges that persist in the bioinformatic analysis of NGS data in medical genetics. We describe and attempt to quantitatively assess the remaining problems, such as the quality of the reference genome sequence, reproducible coverage biases, or variant calling accuracy in complex regions of the genome. We also discuss the prospects of switching to the complete human genome assembly or the human pan-genome and important caveats associated with such a switch. We touch on arguably the hardest problem of NGS data analysis for medical genomics, namely, the annotation of genetic variants and their subsequent interpretation. We highlight the most challenging aspects of annotation and prioritization of both coding and non-coding variants. Finally, we demonstrate the persistent prevalence of pathogenic variants in the coding genome, and outline research directions that may enhance the efficiency of NGS-based disease diagnostics.
Collapse
Affiliation(s)
- Yury A Barbitoff
- Dpt. of Genomic Medicine, D.O. Ott Research Institute of Obstetrics, Gynaecology, and Reproductology, Mendeleevskaya line 3, 199034, St. Petersburg, Russia
- Bioinformatics Institute, Kentemirovskaya st. 2A, 197342, St. Petersburg, Russia
| | - Mikhail O Ushakov
- Dpt. of Genomic Medicine, D.O. Ott Research Institute of Obstetrics, Gynaecology, and Reproductology, Mendeleevskaya line 3, 199034, St. Petersburg, Russia
| | - Tatyana E Lazareva
- Dpt. of Genomic Medicine, D.O. Ott Research Institute of Obstetrics, Gynaecology, and Reproductology, Mendeleevskaya line 3, 199034, St. Petersburg, Russia
| | - Yulia A Nasykhova
- Dpt. of Genomic Medicine, D.O. Ott Research Institute of Obstetrics, Gynaecology, and Reproductology, Mendeleevskaya line 3, 199034, St. Petersburg, Russia
| | - Andrey S Glotov
- Dpt. of Genomic Medicine, D.O. Ott Research Institute of Obstetrics, Gynaecology, and Reproductology, Mendeleevskaya line 3, 199034, St. Petersburg, Russia
| | - Alexander V Predeus
- Bioinformatics Institute, Kentemirovskaya st. 2A, 197342, St. Petersburg, Russia
| |
Collapse
|
3
|
Dueñas Rey A, Del Pozo Valero M, Bouckaert M, Wood KA, Van den Broeck F, Daich Varela M, Thomas HB, Van Heetvelde M, De Bruyne M, Van de Sompele S, Bauwens M, Lenaerts H, Mahieu Q, Josifova D, Rivolta C, O'Keefe RT, Ellingford J, Webster AR, Arno G, Ayuso C, De Zaeytijd J, Leroy BP, De Baere E, Coppieters F. Combining a prioritization strategy and functional studies nominates 5'UTR variants underlying inherited retinal disease. Genome Med 2024; 16:7. [PMID: 38184646 PMCID: PMC10771650 DOI: 10.1186/s13073-023-01277-1] [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: 06/16/2023] [Accepted: 12/15/2023] [Indexed: 01/08/2024] Open
Abstract
BACKGROUND 5' untranslated regions (5'UTRs) are essential modulators of protein translation. Predicting the impact of 5'UTR variants is challenging and rarely performed in routine diagnostics. Here, we present a combined approach of a comprehensive prioritization strategy and functional assays to evaluate 5'UTR variation in two large cohorts of patients with inherited retinal diseases (IRDs). METHODS We performed an isoform-level re-analysis of retinal RNA-seq data to identify the protein-coding transcripts of 378 IRD genes with highest expression in retina. We evaluated the coverage of their 5'UTRs by different whole exome sequencing (WES) kits. The selected 5'UTRs were analyzed in whole genome sequencing (WGS) and WES data from IRD sub-cohorts from the 100,000 Genomes Project (n = 2397 WGS) and an in-house database (n = 1682 WES), respectively. Identified variants were annotated for 5'UTR-relevant features and classified into seven categories based on their predicted functional consequence. We developed a variant prioritization strategy by integrating population frequency, specific criteria for each category, and family and phenotypic data. A selection of candidate variants underwent functional validation using diverse approaches. RESULTS Isoform-level re-quantification of retinal gene expression revealed 76 IRD genes with a non-canonical retina-enriched isoform, of which 20 display a fully distinct 5'UTR compared to that of their canonical isoform. Depending on the probe design, 3-20% of IRD genes have 5'UTRs fully captured by WES. After analyzing these regions in both cohorts, we prioritized 11 (likely) pathogenic variants in 10 genes (ARL3, MERTK, NDP, NMNAT1, NPHP4, PAX6, PRPF31, PRPF4, RDH12, RD3), of which 7 were novel. Functional analyses further supported the pathogenicity of three variants. Mis-splicing was demonstrated for the PRPF31:c.-9+1G>T variant. The MERTK:c.-125G>A variant, overlapping a transcriptional start site, was shown to significantly reduce both luciferase mRNA levels and activity. The RDH12:c.-123C>T variant was found in cis with the hypomorphic RDH12:c.701G>A (p.Arg234His) variant in 11 patients. This 5'UTR variant, predicted to introduce an upstream open reading frame, was shown to result in reduced RDH12 protein but unaltered mRNA levels. CONCLUSIONS This study demonstrates the importance of 5'UTR variants implicated in IRDs and provides a systematic approach for 5'UTR annotation and validation that is applicable to other inherited diseases.
Collapse
Affiliation(s)
- Alfredo Dueñas Rey
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Marta Del Pozo Valero
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
- Department of Genetics, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz, University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
| | - Manon Bouckaert
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Katherine A Wood
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicines and Health, University of Manchester, Manchester, UK
| | - Filip Van den Broeck
- Department of Ophthalmology, Ghent University Hospital, Ghent, Belgium
- Department of Head & Skin, Ghent University, Ghent, Belgium
| | - Malena Daich Varela
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital, London, UK
| | - Huw B Thomas
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicines and Health, University of Manchester, Manchester, UK
| | - Mattias Van Heetvelde
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Marieke De Bruyne
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Stijn Van de Sompele
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Miriam Bauwens
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Hanne Lenaerts
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Quinten Mahieu
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | | | - Carlo Rivolta
- Department of Ophthalmology, University of Basel, Basel, Switzerland
- Institute of Molecular and Clinical Ophthalmology Basel (IOB), Basel, Switzerland
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Raymond T O'Keefe
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicines and Health, University of Manchester, Manchester, UK
| | - Jamie Ellingford
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicines and Health, University of Manchester, Manchester, UK
- Genomics England, London, UK
- Manchester Centre for Genomic Medicine, St Mary's Hospital, Manchester University NHS Foundation Trust, Manchester, UK
| | - Andrew R Webster
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital, London, UK
| | - Gavin Arno
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital, London, UK
| | - Carmen Ayuso
- Department of Genetics, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz, University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Center for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Julie De Zaeytijd
- Department of Ophthalmology, Ghent University Hospital, Ghent, Belgium
- Department of Head & Skin, Ghent University, Ghent, Belgium
| | - Bart P Leroy
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Ophthalmology, Ghent University Hospital, Ghent, Belgium
- Department of Head & Skin, Ghent University, Ghent, Belgium
- Division of Ophthalmology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Elfride De Baere
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium
| | - Frauke Coppieters
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Ghent, Belgium.
- Department of Biomolecular Medicine, Ghent University, Corneel Heymanslaan 10, Ghent, 9000, Belgium.
- Department of Pharmaceutics, Ghent University, Ghent, Belgium.
| |
Collapse
|