Identification of differentially expressed genes in blood cells of narcolepsy patients.
OBJECTIVE
A close association between the human leukocyte antigen (HLA)-DRB1*1501/DQB1*0602 and abnormalities in some inflammatory cytokines have been demonstrated in narcolepsy. Specific alterations in the immune system have been suggested to occur in this disorder. We attempted to identify alterations in gene expression underlying the abnormalities in the blood cells of narcoleptic patients.


METHODS
Total RNA from 12 narcolepsy-cataplexy patients and from 12 age- and sex-matched healthy controls were pooled. The pooled samples were initially screened for candidate genes for narcolepsy by differential display analysis using annealing control primers (ACP). The second screening of the samples was carried out by semiquantitative PCR using gene-specific primers. Finally, the expression levels of the candidate genes were further confirmed by quantitative real-time PCR using a new set of samples (20 narcolepsy-cataplexy patients and 20 healthy controls).


RESULTS
The second screening revealed differential expression of 4 candidate genes. Among them, MX2 was confirmed as a significantly down-regulated gene in the white blood cells of narcoleptic patients by quantitative real-time PCR.


CONCLUSIONS
We found the MX2 gene to be significantly less expressed in comparison with normal subjects in the white blood cells of narcoleptic patients. This gene is relevant to the immune system. Although differential display analysis using ACP technology has a limitation in that it does not help in determining the functional mechanism underlying sleep/wakefulness dysregulation, it is useful for identifying novel genetic factors related to narcolepsy, such as HLA molecules. Further studies are required to explore the functional relationship between the MX2 gene and narcolepsy pathophysiology.
Tanaka
Susumu
S
The Sleep Disorders Project, Department of Sleep Disorders Research, Tokyo Institute of Psychiatry, Setagaya-ku, Tokyo, Japan. stanaka@prit.go.jp
Honda
Yutaka
Y
Honda
Makoto
M
D002352:Carrier Proteins / Q000235:genetics; D002385:Cataplexy / Q000235:genetics* / Q000276:immunology; D015536:Down-Regulation / Q000235:genetics; D019204:GTP-Binding Proteins / Q000235:genetics*; D015870:Gene Expression / Q000502:physiology; D005819:Genetic Markers / Q000235:genetics; D006683:HLA-DQ Antigens / Q000235:genetics*; D059866:HLA-DQ beta-Chains; D006684:HLA-DR Antigens / Q000235:genetics*; D059811:HLA-DRB1 Chains; D006801:Humans; D007962:Leukocytes / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000235:genetics*; D024101:Mitochondrial Proteins / Q000235:genetics; D064547:Myxovirus Resistance Proteins; D009290:Narcolepsy / Q000235:genetics* / Q000276:immunology; D012333:RNA, Messenger / Q000235:genetics; D016601:RNA-Binding Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D025262:Vacuolar Proton-Translocating ATPases / Q000235:genetics; D001613:beta 2-Microglobulin / Q000235:genetics
D002352:Carrier Proteins; D005819:Genetic Markers; D006683:HLA-DQ Antigens; D059866:HLA-DQ beta-Chains; C069051:HLA-DQB1 antigen; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; C489631:HLA-DRB1*15:01 antigen; C468762:IFI6 protein, human; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D064547:Myxovirus Resistance Proteins; C115374:PRPF8 protein, human; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D001613:beta 2-Microglobulin; C462522:ATP6V1E2 protein, human; D019204:GTP-Binding Proteins; D025262:Vacuolar Proton-Translocating ATPases
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