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Eur J Med Genet. 2018 Nov 12. pii: S1769-7212(18)30160-5. doi: 10.1016/j.ejmg.2018.11.008. [Epub ahead of print]

A homozygous variant in RRM2B is associated with severe metabolic acidosis and early neonatal death.

Author information

1
Pediatric Genomics Discovery Program, Department of Pediatrics, Section of Critical Care Medicine, Yale University School of Medicine, New Haven, CT, USA.
2
Department of Cancer Biology and Drug Discovery, College of Medical Technology, Taipei Medical University, Taipei, 110, Taiwan; Sino-American Cancer Foundation, Temple City, CA, USA.
3
Department of Genetics, Yale University School of Medicine, New Haven, CT, USA.
4
Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA.
5
Department of Cancer Biology and Drug Discovery, College of Medical Technology, Taipei Medical University, Taipei, 110, Taiwan; Sino-American Cancer Foundation, Temple City, CA, USA. Electronic address: yyen@tmu.edu.tw.
6
Pediatric Genomics Discovery Program, Department of Pediatrics, Section of Critical Care Medicine, Yale University School of Medicine, New Haven, CT, USA. Electronic address: saquib.lakhani@yale.edu.

Abstract

RRM2B encodes the crucial p53-inducible ribonucleotide reductase small subunit 2 homolog (p53R2), which is required for DNA synthesis throughout the cell cycle. Mutations in this gene have been associated with a lethal mitochondrial depletion syndrome. Here we present the case of an infant with a novel homozygous p.Asn221Ser mutation in RRM2B who developed hypotonia, failure to thrive, sensorineural hearing loss, and severe metabolic lactic acidosis, ultimately progressing to death at 3 months of age. Through molecular modeling using the X-ray crystal structure of p53R2, we demonstrate that this mutation likely causes disruption of a highly conserved helix region of the protein by altering intramolecular interactions. This report expands our knowledge of potential pathogenic RRM2B mutations as well as our understanding of the molecular function of p53R2 and its role in the pathogenesis of mitochondrial DNA depletion.

KEYWORDS:

Lactic acidosis; Mitochondrial DNA depletion; RRM2B; Ribonucleotide reductase; p53R2

PMID:
30439532
DOI:
10.1016/j.ejmg.2018.11.008

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