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.

DESIGNS

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.

CONCLUSION

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-DQB10602 than in subjects without this allele, suggesting that there exists a relationship between the HLA-DQB10602 allele and MX2 gene expression. This might be a possible explanation for the strong HLA association observed in narcolepsy.