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Copy number variant analysis by exome sequencing is an effective approach to optimize diagnostic yield for developmental disorders—the DDD-Africa study

Lookup NU author(s): Dr Laura Yates

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

© The Author(s) 2026.Copy number variants (CNV) contribute significantly to the pathogenic variation associated with developmental disorders. CNV detection is often not included in standard exome sequencing (ES) analysis. Complementary methods such as chromosomal microarray are typically offered in diagnostic laboratories to diagnose pathogenic CNV. In this study, we aimed to develop an effective approach for incorporating CNV detection within our ES analysis process for the Deciphering Developmental Disorders in Africa (DDD-Africa) cohort. We analyzed ES data from 505 probands with a developmental disorder, applying a CNV detection approach that assessed data generated using the tools CANOES and XHMM. When available, parental ES data was used to assess inheritance patterns. We confirmed a diagnosis in 41/505 (8,1%) patients with 43 pathogenic CNV identified in the probands. There were 31 deletions and 12 duplications. Among the 26 probands with parental data, all identified CNV were de novo. The addition of CNV analysis to our ES analysis pipeline resulted in an 8.1% increase in diagnostic yield in the DDD-Africa cohort without additional laboratory cost. This offers a feasible approach which is likely to reduce analytical cost and is suitable for low- and middle-income countries where funding and resources for genomic medicine initiatives are limited.


Publication metadata

Author(s): Louw N, Makay P, Mpangase PT, Shingwenyana B, Goliath Z, Naicker T, Yates LM, Honey E, Mubungu G, Van Den Bogaert K, Firth HV, Hurles ME, Lukusa Tshilobo P, Devriendt K, Krause A, Carstens N, Lumaka A, Lombard Z

Publication type: Article

Publication status: Published

Journal: European Journal of Human Genetics

Year: 2026

Pages: epub ahead of print

Print publication date: 09/07/2026

Online publication date: 09/07/2026

Acceptance date: 26/06/2026

Date deposited: 20/07/2026

ISSN (print): 1018-4813

ISSN (electronic): 1476-5438

Publisher: Springer Nature

URL: https://doi.org/10.1038/s41431-026-02179-7

DOI: 10.1038/s41431-026-02179-7

Data Access Statement: This research generated genomic data (CNV) and clinical data. The CNV will be submitted to ClinVar. In accordance with funder agreements, the complete dataset from the DDD-Africa study, including all phenotypic data, is available on the European Genome-phenome Archive (EGAS00001008319) to ensure public access.


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Funding

Funder referenceFunder name
National Institute of Mental Health of the National Institutes of Health under Award Numbers U01MH115483 and 5U01HD114537

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