AbstractBackground Narcolepsy is a neuropsychiatric disorder characterized by excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, and abnormal rapid eye movement (REM) sleep. Tumor necrosis factor α (TNF α) and its cognate receptors have been reported to be involved in the pathophysiology of narcolepsy in addition to the HLA antigen system. Our study aimed to determine if the TNF-α system was associated with narcolepsy in our patients. Methods We first measured the plasma level of TNF α in 56 narcoleptic patients and 53 control subjects using a highly sensitive enzyme-linked immunosorbent assay. We next determined the genotype of 3 single nucleotide polymorphisms (SNPs) (T-1031C, C-863A, and C-857T) at the promoter region of the TNF-α gene, and one missense SNP (T587G, M196R) at the exon 6 of the tumor necrosis factor receptor 2 gene, TNFR2, in a sample of 75 narcoleptic patients and 201 control subjects by direct sequencing analysis. Results We found a significant elevation of plasma level of TNF α in patients with narcolepsy compared with the control subjects (4.64 pg/mL vs1.06 pg/mL; P=.0013). However, we did not find significant differences between these 2 groups in the allelic and genotypic distributions of the investigated polymorphisms. Conclusions Our study suggests that an increased TNF-α level was associated with narcolepsy in our patients, and that chronic inflammation due to various factors might have led to the increased TNF-α found in our patients.
