Mitochondrial DNA profiling via genomic analysis in mesial temporal lobe epilepsy patients with hippocampal sclerosis
Candan Gurses1, Hulya Azakli2, Ahmet Alptekin3
1Neurology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.
Introduction:
Mitochondria have an essential role in neuronal excitability and neuronal survival. In addition to energy production, mitochondria also play a crucial role in the maintenance of intracellular calcium homeostasis, generation of reactive oxygen species and mechanisms of cell death. There is a relative paucity of data about the role of mitochondria in epilepsy. Mitochondrial genome analysis is rarely carried out in the investigation of some diseases. In mesial temporal lobe epilepsies (MTLE) cases, genome analysis has never been used previously. The aim of this study is to show mitochondrial dysfunctions using genome analysis in patients with MTLE-hippocampal sclerosis (HS).
Methods:
44 patients with MTLE-HS and 86 matched healthy unrelated controls were included in this study. The patients were divided into four groups according to their clinical presentation as the following: Group 1 consists of patients with intractable epilepsy who refused operation; Group 2 of operated seizure free patients; Group 3 of operated patients with seizures; and Group 4 unoperated seizure free patients with or without antiepileptic drugs. Blood samples were used to isolate DNA. Parallel tagged sequencing was employed to allow pyrosequencing of 130 samples. Complete mtDNA is amplified in two overlapping fragments (11 and 9 kb). The PCR amplicons were pooled in equimolar ratios. Titanium kits were used to produce shotgun libraries according to the manufacturer's protocol.
Results:
The average coverage in total was 130 ± 30 and an average of 2365127 bases and 337 bp fragment length was received from all samples. The mean mtDNA heteroplasmy in patients was 26.35 ± 12.3 and in controls 25.03 ± 9.34. Three mutations had prominently high significance in patient samples. The most significantly associated variation was located in the MT-ATP-8 gene (8502 A>T, Asn46Ile) whereas the other two were in the MT-ND4 (11994 C>T, Thr412Ile) and MT-ND5 (13231 A>C, Lys299Gln) genes.
Conclusions:
We have observed that three mutations were significantly related to the presence of epilepsy. These mutations were found at the 8502, 11994, and 13,231 bp of mtDNA, which resulted in amino acid changes at the MT-ATP-8, MT-ND4 and MT-ND5 genes. Finding mutations can lead us to knowing more about the pathophysiology of the MTLE disease.
Insights
Mitochondrial genome analysis revealed three significant mutations in patients with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS). These findings offer new insights into the genetic basis of MTLE-HS and potential therapeutic targets.
Area of Science:
- Neuroscience
- Genetics
- Mitochondrial Biology
Background:
- Mitochondria are vital for neuronal function, energy production, calcium homeostasis, and cell death.
- Mitochondrial dysfunction is implicated in epilepsy, yet its role in mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) is understudied.
- Mitochondrial genome analysis has not been previously applied to MTLE-HS cases.
Purpose of the Study:
- To investigate mitochondrial dysfunction in MTLE-HS patients using mitochondrial genome analysis.
- To identify specific mitochondrial DNA (mtDNA) mutations associated with MTLE-HS.
Main Methods:
- Analyzed mitochondrial genomes from 44 MTLE-HS patients and 86 healthy controls using parallel tagged sequencing.
- Amplified complete mtDNA in two fragments and prepared shotgun libraries.
- Compared mtDNA heteroplasmy levels and identified significant mutations between patient and control groups.
Main Results:
- Identified three mutations with high significance in MTLE-HS patients.
- The most significant mutation was in the MT-ATP-8 gene (8502 A>T, Asn46Ile).
- Other significant mutations were found in the MT-ND4 (11994 C>T, Thr412Ile) and MT-ND5 (13231 A>C, Lys299Gln) genes.
Conclusions:
- Three specific mtDNA mutations are significantly associated with the presence of epilepsy in MTLE-HS patients.
- These mutations lead to amino acid changes in key mitochondrial genes (MT-ATP-8, MT-ND4, MT-ND5).
- These findings contribute to understanding the pathophysiology of MTLE disease and may guide future research.
