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Infantile Cerebellar-Retinal Degeneration Associated With Novel ACO2 Variants: Clinical Features and Insights From a Drosophila Model

Lookup NU author(s): Lucie Taylor, Professor Robert TaylorORCiD, Dr Charlotte Alston

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


Abstract

© 2025 The Author(s). Clinical Genetics published by John Wiley & Sons Ltd. Infantile Cerebellar-Retinal Degeneration (ICRD) is an autosomal recessive neuro-disability associated with hypotonia, seizures, optic atrophy, and retinal degeneration. Recessive variants of the mitochondrial aconitase gene (ACO2) are a known cause of ICRD. Here, we present a paediatric male patient with ICRD, where whole genome sequencing of the family trio revealed segregating heterozygous variants of unknown significance in ACO2. At 4 months, he displayed generalised hypotonia, and by 6 years, visual electrophysiology indicated bilateral optic atrophy. Magnetic Resonance Imaging (MRI) at age seven confirmed optic nerve and cerebellar atrophy, and together with symptoms of developmental delay, align with ICRD. We established a Drosophila animal model to explore the impact of ACO2 loss- and gain-of-function. Manipulating the fly ortholog, mAcon1, through pan-neuronal knock-down or over-expression negatively affected longevity, locomotion, activity, whilst disrupting sleep and circadian rhythms. Mis-expression of mAcon1 in the eye led to impaired visual synaptic transmission and neurodegeneration. These experiments mirrored certain aspects of the human disease, providing a foundation for understanding its biological processes and pathogenic mechanisms, and offering insights into potential targets to screen for future treatments or preventive measures for ACO2-related ICRD.


Publication metadata

Author(s): Buhl E, Garg S, Monaghan M, Preston A, Likeman M, Dare J, Evans J, Taylor LS, Berry I, Urankar K, Spry PGD, Williams C, Taylor RW, Alston CL, Hodge JJL, Majumdar A

Publication type: Article

Publication status: Published

Journal: Clinical Genetics

Year: 2025

Pages: Epub ahead of print

Online publication date: 10/04/2025

Acceptance date: 13/03/2025

Date deposited: 16/05/2025

ISSN (print): 0009-9163

ISSN (electronic): 1399-0004

Publisher: John Wiley and Sons Inc.

URL: https://doi.org/10.1111/cge.14745

DOI: 10.1111/cge.14745

Data Access Statement: The data that supports the findings of this study are available in the supporting Information of this article.


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Funding

Funder referenceFunder name
203105/Z/16/ZWellcome Trust
BBSRC (BB/W000865/1)
Medical Research Council (MR/W019027/1)
Mitochondrial Disease Patient Cohort (G0800674)
LifeArc
Lily Foundation
National Institute for Health Research (NIHR) Post-Doctoral Fellowship (PDF-2018-11-ST2-021)
Pathological Society
UK NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children
UK NIHR Biomedical Research Centre for Ageing and Age-related disease

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