Mitochondrial DNA profiling via genomic analysis in mesial temporal lobe epilepsy patients with hippocampal sclerosis.
BACKGROUND
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.
Neurology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey. Electronic address: candangrss@gmail.com.
Candan
C
Gurses
Genetics, Institute for Experimental Medicine, Istanbul University, Istanbul, Turkey.
Hulya
H
Azakli
Computer Engineering, Istanbul University, Istanbul, Turkey.
Ahmet
A
Alptekin
Genetics, Institute for Experimental Medicine, Istanbul University, Istanbul, Turkey.
Aris
A
Cakiris
Genetics, Institute for Experimental Medicine, Istanbul University, Istanbul, Turkey.
Neslihan
N
Abaci
Genetics, Institute for Experimental Medicine, Istanbul University, Istanbul, Turkey.
Muzaffer
M
Arikan
Computer Engineering, Istanbul University, Istanbul, Turkey.
Olcay
O
Kursun
Neurology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.
Aysen
A
Gokyigit
Genetics, Institute for Experimental Medicine, Istanbul University, Istanbul, Turkey. Electronic address: dustek@istanbul.edu.tr.
Duran
D
Ustek
D000328:Adult; D019943:Amino Acid Substitution; D016022:Case-Control Studies; D016172:DNA Fingerprinting; D004272:DNA, Mitochondrial / Q000235:genetics*; D042967:Electron Transport Complex I / Q000235:genetics*; D004833:Epilepsy, Temporal Lobe / Q000209:etiology / Q000235:genetics* / Q000473:pathology*; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D008297:Male; D028361:Mitochondrial Diseases / Q000150:complications / Q000235:genetics; D024101:Mitochondrial Proteins / Q000235:genetics*; D025261:Mitochondrial Proton-Translocating ATPases / Q000235:genetics*; D020125:Mutation, Missense; D009245:NADH Dehydrogenase / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D012598:Sclerosis; D055815:Young Adult
D004272:DNA, Mitochondrial; D024101:Mitochondrial Proteins; C098483:NADH dehydrogenase subunit 4; C481838:MT-ND5 protein, human; D009245:NADH Dehydrogenase; C513300:MT-ATP8 protein, human; D025261:Mitochondrial Proton-Translocating ATPases; D042967:Electron Transport Complex I
Hippocampal sclerosis; MT-ATP8; MT-ND4; MT-ND5; Mesial temporal lobe epilepsy