Role of the GRIN1 gene polymorphism in the formation of post-traumatic epilepsy

Introduction: NMDA receptors are involved in the pathogenesis of seizures, as it subunit is coded for by the GRIN1 gene. Different GRIN1 mutations are known in patients with different forms of epilepsy and encephalopathy. However, no data are available on the participation of the GRIN1 gene and its polymorphisms in the development of post-traumatic epilepsy (PTE).

Aim: To determine the influence of single-nucleotide rs1126442 polymorphism of GRIN1 on the risk of PTE formation.

Materials and methods: A total of 140 patients were examined, which included 69 patients with PTE and 71 patients with genetic epilepsy. All patients underwent a comprehensive examination, with evaluation of history, neurological status, electroencephalography (EEG) and neuroimaging results, and genotyping of blood samples by real-time polymerase chain reaction. The control sample for genetic examination was venous blood from 60 healthy individuals.

Results:  Focal seizures with transition to bilateral and tonic–clonic seizures were predominant in the PTE group. Neuroimaging revealed dystrophic, cystic, and cystogliotic alterations and signs of external hydrocephaly. EEG recorded interictal and ictal epileptiform activity and slowing of theta waves. Genotyping by rs1126442 polymorphism of GRIN1 revealed predominance of heterozygous G/A and homozygous A/A genotypes in patients with PTE in the codominant (odds ratio (OD)=3.43; 95% confidence index (CI) 1.56–7.55; p=0.0047), dominant (OR=3.24; 95% CI 1.57–6.68; p=0.0011), and superdominant (OR=2.90; 95% CI 1.36–6.22; p=0.0048) inheritance models. The carriage of heterozygous G/A rs1126442 genotype of GRIN1 was associated with an epileptiform activity in the EEG of all patients with epilepsy (OR=2.40; 95% CI 1.11–5.20; p=0.024).

Conclusion: The carriage of heterozygous G/A genotype and homozygous A/A rs 1126442 genotype of GRIN1 in the dominant and codominant inheritance models is associated with a high risk of development of epilepsy after craniocerebral trauma. The carriage of heterozygous G/A rs 1126442 genotype of GRIN1 is associated with an epileptiform activity in EEG.