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Journal article

Use of genome sequencing to hunt for cryptic second-hit variants: analysis of 31 cases recruited to the 100 000 Genomes Project

Abstract:
Background: Current clinical testing methods used to uncover the genetic basis of rare disease have inherent limitations, which can lead to causative pathogenic variants being missed. Within the rare disease arm of the 100 000 Genomes Project (100kGP), families were recruited under the clinical indication ‘single autosomal recessive mutation in rare disease’. These participants presented with strong clinical suspicion for a specific autosomal recessive disorder, but only one suspected pathogenic variant had been identified through standard-of-care testing. Whole genome sequencing (WGS) aimed to identify cryptic ‘second-hit’ variants. Methods: To investigate the 31 families with available data that remained unsolved following formal review within the 100kGP, SVRare was used to aggregate structural variants present in <1% of 100kGP participants. Small variants were assessed using population allele frequency data and SpliceAI. Literature searches and publicly available online tools were used for further annotation of pathogenicity. Results: Using these strategies, 8/31 cases were solved, increasing the overall diagnostic yield of this cohort from 10/41 (24.4%) to 18/41 (43.9%). Exemplar cases include a patient with cystic fibrosis harbouring a novel exonic LINE1 insertion in CFTR and a patient with generalised arterial calcification of infancy with complex interlinked duplications involving exons 2–6 of ENPP1. Although ambiguous by short-read WGS, the ENPP1 variant structure was resolved using optical genome mapping and RNA analysis. Conclusion: Systematic examination of cryptic variants across a multi-disease cohort successfully identifies additional pathogenic variants. WGS data analysis in autosomal recessive rare disease should consider complex structural and small intronic variants as potentially pathogenic second hits
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1136/jmg-2023-109362
Publication website:
https://eprints.whiterose.ac.uk/202596/1/jmg-2023-109362.full.pdf

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Institution:
University of Oxford
Role:
Author
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Institution:
University of Oxford
Role:
Author
ORCID:
0000-0001-8001-8494
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Institution:
University of Oxford
Role:
Author
ORCID:
0000-0002-0115-5851
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Role:
Author
ORCID:
0000-0001-7089-0502


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Funder identifier:
10.13039/100010269
Grant:
203141/Z/16/Z
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Funder identifier:
10.13039/501100000265
Grant:
MR/W01761X/1
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Funder identifier:
10.13039/501100000289
More from this funder
Funder identifier:
10.13039/501100013373


Publisher:
BMJ Publishing Group
Journal:
Journal of Medical Genetics More from this journal
Volume:
60
Issue:
12
Pages:
1235-1244
Publication date:
2023-08-09
Acceptance date:
2023-07-28
DOI:
EISSN:
1468-6244
ISSN:
0022-2593


Language:
English
Keywords:
Pubs id:
1506257
Local pid:
pubs:1506257
Source identifiers:
W4385716530
Deposit date:
2026-05-12
ARK identifier:
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