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The Y831C Mutation of the POLG Gene in Dementia
Eugenia Borgione1, Mariangela Lo Giudice1, Sandro Santa Paola1
1Oasi Research Institute-IRCCS, 94018 Troina, Italy.
Background:
The POLG gene encodes the catalytic subunit of DNA polymerase γ, which is crucial for mitochondrial DNA (mtDNA) repair and replication. Gene mutation alters the stability of mtDNA and is associated with several clinical presentations, such as dysarthria and ophthalmoplegia (SANDO), progressive external ophthalmoplegia (PEO), spinocerebellar ataxia and epilepsy (SCAE), Alpers syndrome, and sensory ataxic neuropathy. Recent evidence has also indicated that POLG mutations may be involved in some neurodegenerative disorders, although systematic screening is currently lacking.
Methods:
To investigate the frequency of POLG gene mutations in neurodegenerative disorders, we screened a group of 33 patients affected by neurodegenerative diseases, including Parkinson's disease, some atypical parkinsonisms, and dementia of different types.
Results:
Mutational analysis revealed the presence of the heterozygous Y831C mutation in two patients, one with frontotemporal dementia and one with Lewy body dementia. The allele frequency of this mutation reported by the 1000 Genomes Project in the healthy population is 0.22%, while in our group of patients, it was 3.03%, thus showing a statistically significant difference between the two groups.
Conclusions:
Our results may expand the genotype-phenotype spectrum associated with mutations in the POLG gene and strengthen the hypothesis of a pathogenic role of the Y831C mutation in neurodegeneration.
Insights
Mutations in the POLG gene, vital for mitochondrial DNA maintenance, were investigated in neurodegenerative diseases. The Y831C mutation was found more frequently in patients, suggesting a role in neurodegeneration.
Area of Science:
- Genetics and Molecular Biology
- Neuroscience
- Mitochondrial Biology
Background:
- The POLG gene encodes DNA polymerase gamma, essential for mitochondrial DNA (mtDNA) replication and repair.
- Mutations in POLG are linked to various mitochondrial disorders, including SANDO, PEO, SCAE, Alpers syndrome, and sensory ataxic neuropathy.
- Emerging evidence suggests POLG mutations may contribute to neurodegenerative diseases, but systematic studies are limited.
Purpose of the Study:
- To determine the frequency of POLG gene mutations in patients with neurodegenerative disorders.
- To explore the potential association between POLG mutations and conditions like Parkinson's disease, atypical parkinsonisms, and various dementias.
Main Methods:
- Screening of 33 patients diagnosed with neurodegenerative diseases for POLG gene mutations.
- Mutational analysis to identify specific POLG variants within the patient cohort.
Main Results:
- The heterozygous Y831C POLG mutation was identified in two patients: one with frontotemporal dementia and one with Lewy body dementia.
- The allele frequency of Y831C was significantly higher in the patient group (3.03%) compared to the healthy population (0.22% from 1000 Genomes Project).
Conclusions:
- The findings suggest that the Y831C POLG mutation may play a pathogenic role in neurodegeneration.
- This study expands the known genotype-phenotype spectrum for POLG gene mutations.
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