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Uniparental isodisomy of chromosome 2 causing MRPL44-related multisystem mitochondrial disease

Lookup NU author(s): Dr Langping He, Professor Robert Taylor

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Abstract

© 2021, The Author(s), under exclusive licence to Springer Nature B.V.Mutations in nuclear-encoded protein subunits of the mitochondrial ribosome are an increasingly recognised cause of oxidative phosphorylation system (OXPHOS) disorders. Among them, mutations in the MRPL44 gene, encoding a structural protein of the large subunit of the mitochondrial ribosome, have been identified in four patients with OXPHOS defects and early-onset hypertrophic cardiomyopathy with or without additional clinical features. A 23-year-old individual with cardiac and skeletal myopathy, neurological involvement, and combined deficiency of OXPHOS complexes in skeletal muscle was clinically and genetically investigated. Analysis of whole-exome sequencing data revealed a homozygous mutation in MRPL44 (c.467 T > G), which was not present in the biological father, and a region of homozygosity involving most of chromosome 2, raising the possibility of uniparental disomy. Short-tandem repeat and genome-wide SNP microarray analyses of the family trio confirmed complete maternal uniparental isodisomy of chromosome 2. Mitochondrial ribosome assembly and mitochondrial translation were assessed in patient derived-fibroblasts. These studies confirmed that c.467 T > G affects the stability or assembly of the large subunit of the mitochondrial ribosome, leading to impaired mitochondrial protein synthesis and decreased levels of multiple OXPHOS components. This study provides evidence of complete maternal uniparental isodisomy of chromosome 2 in a patient with MRPL44-related disease, and confirms that MRLP44 mutations cause a mitochondrial translation defect that may present as a multisystem disorder with neurological involvement.

Publication metadata

Author(s): Horga A, Manole A, Mitchell AL, Bugiardini E, Hargreaves IP, Mowafi W, Bettencourt C, Blakely EL, He L, Polke JM, Woodward CE, Dalla Rosa I, Shah S, Pittman AM, Quinlivan R, Reilly MM, Taylor RW, Holt IJ, Hanna MG, Pitceathly RDS, Spinazzola A, Houlden H

Publication type: Article

Publication status: Published

Journal: Molecular Biology Reports

Year: 2021

Volume: 48

Pages: 2093–2104

Online publication date: 19/03/2021

Acceptance date: 28/01/2021

ISSN (print): 0301-4851

ISSN (electronic): 1573-4978

Publisher: Springer Science and Business Media B.V.

URL: https://doi.org/10.1007/s11033-021-06188-1

DOI: 10.1007/s11033-021-06188-1

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