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Bi-allelic ACBD6 variants lead to a neurodevelopmental syndrome with progressive and complex movement disorders

Lookup NU author(s): Professor Robert Taylor

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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) 2023. Published by Oxford University Press on behalf of the Guarantors of Brain. The acyl-CoA-binding domain-containing protein 6 (ACBD6) is ubiquitously expressed, plays a role in the acylation of lipids and proteins and regulates the N-myristoylation of proteins via N-myristoyltransferase enzymes (NMTs). However, its precise function in cells is still unclear, as is the consequence of ACBD6 defects on human pathophysiology. Using exome sequencing and extensive international data sharing efforts, we identified 45 affected individuals from 28 unrelated families (consanguinity 93%) with bi-allelic pathogenic, predominantly loss-of-function (18/20) variants in ACBD6. We generated zebrafish and Xenopus tropicalis acbd6 knockouts by CRISPR/Cas9 and characterized the role of ACBD6 on protein N-myristoylation with myristic acid alkyne (YnMyr) chemical proteomics in the model organisms and human cells, with the latter also being subjected further to ACBD6 peroxisomal localization studies. The affected individuals (23 males and 22 females), aged 1-50 years, typically present with a complex and progressive disease involving moderate-to-severe global developmental delay/intellectual disability (100%) with significant expressive language impairment (98%), movement disorders (97%), facial dysmorphism (95%) and mild cerebellar ataxia (85%) associated with gait impairment (94%), limb spasticity/hypertonia (76%), oculomotor (71%) and behavioural abnormalities (65%), overweight (59%), microcephaly (39%) and epilepsy (33%). The most conspicuous and common movement disorder was dystonia (94%), frequently leading to early-onset progressive postural deformities (97%), limb dystonia (55%) and cervical dystonia (31%). A jerky tremor in the upper limbs (63%), a mild head tremor (59%), parkinsonism/hypokinesia developing with advancing age (32%) and simple motor and vocal tics were among other frequent movement disorders. Midline brain malformations including corpus callosum abnormalities (70%), hypoplasia/agenesis of the anterior commissure (66%), short midbrain and small inferior cerebellar vermis (38% each) as well as hypertrophy of the clava (24%) were common neuroimaging findings. Acbd6-deficient zebrafish and Xenopus models effectively recapitulated many clinical phenotypes reported in patients including movement disorders, progressive neuromotor impairment, seizures, microcephaly, craniofacial dysmorphism and midbrain defects accompanied by developmental delay with increased mortality over time. Unlike ACBD5, ACBD6 did not show a peroxisomal localization and ACBD6-deficiency was not associated with altered peroxisomal parameters in patient fibroblasts. Significant differences in YnMyr-labelling were observed for 68 co- and 18 post-translationally N-myristoylated proteins in patient-derived fibroblasts. N-myristoylation was similarly affected in acbd6-deficient zebrafish and X. tropicalis models, including Fus, Marcks and Chchd-related proteins implicated in neurological diseases. The present study provides evidence that bi-allelic pathogenic variants in ACBD6 lead to a distinct neurodevelopmental syndrome accompanied by complex and progressive cognitive and movement disorders.


Publication metadata

Author(s): Kaiyrzhanov R, Rad A, Lin S-J, Bertoli-Avella A, Kallemeijn WW, Godwin A, Zaki MS, Huang K, Lau T, Petree C, Efthymiou S, Karimiani EG, Hempel M, Normand EA, Rudnik-Schoneborn S, Schatz UA, Baggelaar MP, Ilyas M, Sultan T, Alvi JR, Ganieva M, Fowler B, Aanicai R, Tayfun GA, Al Saman A, Alswaid A, Amiri N, Asilova N, Shotelersuk V, Yeetong P, Azam M, Babaei M, Monajemi GB, Mohammadi P, Samie S, Banu SH, Pinto Basto J, Kortum F, Bauer M, Bauer P, Beetz C, Garshasbi M, Issa AH, Eyaid W, Ahmed H, Hashemi N, Hassanpour K, Herman I, Ibrohimov S, Abdul-Majeed BA, Imdad M, Isrofilov M, Kaiyal Q, Khan S, Kirmse B, Koster J, Lourenco CM, Mitani T, Moldovan O, Murphy D, Najafi M, Pehlivan D, Rocha ME, Salpietro V, Schmidts M, Shalata A, Mahroum M, Talbeya JK, Taylor RW, Vazquez D, Vetro A, Waterham HR, Zaman M, Schrader TA, Chung WK, Guerrini R, Lupski JR, Gleeson J, Suri M, Jamshidi Y, Bhatia KP, Vona B, Schrader M, Severino M, Guille M, Tate EW, Varshney GK, Houlden H, Maroofian R

Publication type: Article

Publication status: Published

Journal: Brain

Year: 2024

Volume: 147

Issue: 4

Pages: 1436-1456

Print publication date: 01/04/2024

Online publication date: 10/11/2023

Acceptance date: 20/10/2023

Date deposited: 22/04/2024

ISSN (print): 0006-8950

ISSN (electronic): 1460-2156

Publisher: Oxford University Press

URL: https://doi.org/10.1093/brain/awad380

DOI: 10.1093/brain/awad380

PubMed id: 37951597


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Funding

Funder referenceFunder name
203105/Z/16/ZWellcome Trust
Ataxia UK
Brain Research UK
G0601943
G0800674
Lily Foundation
MR/S005021/1Medical Research Council (MRC)
MR/S01165X/1
Multiple System Atrophy Trust (MSA Trust)
Muscular Dystrophy Association (MDA USA
MR/V012177/1
MR/W019027/1
Muscular Dystrophy UK (MDUK)
National Institute for Health Research University College London Hospitals Biomedical Research Centre
Pathological Society
Rosetree Trust
Synaptopathies
UK NHS Highly Specialized Service for Rare Mitochondrial Disorders of Adults and Children
UK NIHR Biomedical Research Centre for Ageing and Age-related disease award to the Newcastle upon Tyne Foundation Hospitals NHS Trust
Sparks GOSH Charity
WT093205 MA
Wellcome Trust
WT104033AIA

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