Molecular and biochemical characterisation of a novel mutation in POLG associated with Alpers syndrome

Schaller, André; Hahn, Dagmar; Jackson, Christopher B; Kern, Ilse; Chardot, Christophe; Belli, Dominique C; Gallati, Sabina; Nuoffer, Jean-Marc (2011). Molecular and biochemical characterisation of a novel mutation in POLG associated with Alpers syndrome. BMC neurology, 11, p. 4. London: BioMed Central 10.1186/1471-2377-11-4

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Background

DNA polymerase γ (POLG) is the only known mitochondrial DNA (mtDNA) polymerase. It mediates mtDNA replication and base excision repair. Mutations in the POLG gene lead to reduction of functional mtDNA (mtDNA depletion and/or deletions) and are therefore predicted to result in defective oxidative phosphorylation (OXPHOS). Many mutations map to the polymerase and exonuclease domains of the enzyme and produce a broad clinical spectrum. The most frequent mutation p.A467T is localised in the linker region between these domains. In compound heterozygote patients the p.A467T mutation has been described to be associated amongst others with fatal childhood encephalopathy. These patients have a poorer survival rate compared to homozygotes.
Methods

mtDNA content in various tissues (fibroblasts, muscle and liver) was quantified using quantitative PCR (qPCR). OXPHOS activities in the same tissues were assessed using spectrophotometric methods and catalytic stain of BN-PAGE.
Results

We characterise a novel splice site mutation in POLG found in trans with the p.A467T mutation in a 3.5 years old boy with valproic acid induced acute liver failure (Alpers-Huttenlocher syndrome). These mutations result in a tissue specific depletion of the mtDNA which correlates with the OXPHOS-activities.
Conclusions

mtDNA depletion can be expressed in a high tissue-specific manner and confirms the need to analyse primary tissue. Furthermore, POLG analysis optimises clinical management in the early stages of disease and reinforces the need for its evaluation before starting valproic acid treatment.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Gynaecology, Paediatrics and Endocrinology (DFKE) > Clinic of Paediatric Medicine
04 Faculty of Medicine > Department of Haematology, Oncology, Infectious Diseases, Laboratory Medicine and Hospital Pharmacy (DOLS) > Institute of Clinical Chemistry

UniBE Contributor:

Schaller, André; Hahn, Dagmar Karen; Jackson, Christopher; Gallati, Sabina and Nuoffer, Jean-Marc

ISSN:

1471-2377

Publisher:

BioMed Central

Language:

English

Submitter:

Anette van Dorland

Date Deposited:

04 Oct 2013 14:22

Last Modified:

20 Jul 2022 10:02

Publisher DOI:

10.1186/1471-2377-11-4

PubMed ID:

21235791

Web of Science ID:

000286811500001

BORIS DOI:

10.7892/boris.7626

URI:

https://boris.unibe.ch/id/eprint/7626 (FactScience: 212925)

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