MX2 gene expression tends to be downregulated in subjects with HLA-DQB1*0602.
OBJECTIVE
There is a close association between narcolepsy and the human leukocyte antigen (HLA)-DQB1*0602. The detailed influence and function of this specific HLA allele with regard to narcolepsy have not yet been elucidated. Our previous report identified the myxovirus resistance 2 (MX2) gene as a narcolepsy-specific dysregulated gene; however, the report had a limitation-the control groups were not HLA matched. In this study, we examined the possibility of an association between MX2 expression and HLA haplotypes.


METHODS
The expression levels of the MX2 gene in 3 groups (24 narcolepsy with cataplexy patients; 24 age-, sex-, and HLA-DQB1 genotype-matched controls; and 24 age- and sex-matched controls without the HLA-DQB1*0602 allele) were measured by quantitative real-time RT-PCR.


RESULTS
The expression level of the MX2 gene tended to be downregulated in subjects carrying HLA-DQB1*0602, compared with that of the control subjects without this allele. There was no difference in the MX2 expression level between the narcolepsy subjects and the HLA-DQB1 genotype-matched control subjects.


CONCLUSIONS
Our previous finding-the narcolepsy-specific reduction of MX2 gene expression-was not replicated in this follow-up study. The expression level of the MX2 gene in white blood cells was found to be lower in subjects with the HLA-DQB1*0602 than in subjects without this allele, suggesting that there exists a relationship between the HLA-DQB1*0602 allele and MX2 gene expression. This might be a possible explanation for the strong HLA association observed in narcolepsy.
Tanaka
Susumu
S
Sleep Disorders Project, Department of Sleep Disorders Research, Tokyo Institute of Psychiatry, Setagaya-ku, Tokyo, Japan.
Honda
Yutaka
Y
Honda
Makoto
M
D000328:Adult; D000483:Alleles; D002385:Cataplexy / Q000235:genetics*; D015536:Down-Regulation / Q000235:genetics*; D005260:Female; D019204:GTP-Binding Proteins / Q000235:genetics*; D006580:Genetic Carrier Screening; D005838:Genotype; D006683:HLA-DQ Antigens / Q000235:genetics*; D059866:HLA-DQ beta-Chains; D006239:Haplotypes; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics*; D064547:Myxovirus Resistance Proteins; D009290:Narcolepsy / Q000235:genetics*; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction
D006683:HLA-DQ Antigens; D059866:HLA-DQ beta-Chains; C069051:HLA-DQB1 antigen; D008562:Membrane Glycoproteins; D064547:Myxovirus Resistance Proteins; D019204:GTP-Binding Proteins