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EPHA2 Segregates with Microphthalmia and Congenital Cataracts in Two Unrelated Families

Harding, P; Toms, M; Schiff, E; Owen, N; Bell, S; Lloyd, IC; Moosajee, M; (2021) EPHA2 Segregates with Microphthalmia and Congenital Cataracts in Two Unrelated Families. International Journal of Molecular Sciences , 22 (4) , Article 2190. 10.3390/ijms22042190. Green open access

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Abstract

EPHA2 is a transmembrane tyrosine kinase receptor that, when disrupted, causes congenital and age-related cataracts. Cat-Map reports 22 pathogenic EPHA2 variants associated with congenital cataracts, variable microcornea, and lenticonus, but no previous association with microphthalmia (small, underdeveloped eye, ≥2 standard deviations below normal axial length). Microphthalmia arises from ocular maldevelopment with >90 monogenic causes, and can include a complex ocular phenotype. In this paper, we report two pathogenic EPHA2 variants in unrelated families presenting with bilateral microphthalmia and congenital cataracts. Whole genome sequencing through the 100,000 Genomes Project and cataract-related targeted gene panel testing identified autosomal dominant heterozygous mutations segregating with the disease: (i) missense c.1751C>T, p.(Pro584Leu) and (ii) splice site c.2826-9G>A. To functionally validate pathogenicity, morpholino knockdown of epha2a/epha2b in zebrafish resulted in significantly reduced eye size ± cataract formation. Misexpression of N-cadherin and retained fibre cell nuclei were observed in the developing lens of the epha2b knockdown morphant fish by 3 days post-fertilisation, which indicated a putative mechanism for microphthalmia pathogenesis through disruption of cadherin-mediated adherens junctions, preventing lens maturation and the critical signals stimulating eye growth. This study demonstrates a novel association of EPHA2 with microphthalmia, suggesting further analysis of pathogenic variants in unsolved microphthalmia cohorts may increase molecular diagnostic rates.

Type: Article
Title: EPHA2 Segregates with Microphthalmia and Congenital Cataracts in Two Unrelated Families
Open access status: An open access version is available from UCL Discovery
DOI: 10.3390/ijms22042190
Publisher version: https://doi.org/10.3390/ijms22042190
Language: English
Additional information: This is an open access article distributed under the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
Keywords: EPHA2; microphthalmia; cataracts; congenital; eye; development; whole genome sequencing (WGS); next-generation sequencing (NGS); genetics; zebrafish
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Ophthalmology
URI: https://discovery.ucl.ac.uk/id/eprint/10123470
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