Narcolepsy and HLA in the Japanese

Narcolepsy is characterized by excessive daytime sleepiness and cataplexy. It had been reported that 100% of Japanese and Caucasian narcoleptic patients are HLA-DR2 and HLA-DQw1 positive; last year, however, exceptionally rare cases of DR2-negative narcolepsy were reported. Conversely, we tested 190 Japanese narcoleptic patients, and all were still DR2 and DQw1 positive. Among several symptoms in narcoleptic patients, HLA-DR2 showed the strongest association with cataplexy. Exclusive association has been demonstrated between narcolepsy and a specific band of EcoRI-digested DQ beta fragments. In this paper Taq I-digested genomic DNAs were hybridized with a DQ alpha probe, and five specific bands were observed to associate strongly with particular HLA-DR or D specificities. Interestingly, the 6.0-kb band was found in 100% of 28 narcoleptic patients and in 54% of DR2-positive normal control subjects. For the time being, HLA-Dw2 is the better marker of the HLA-associating narcoleptic gene than is DR2, DQw1, 2.4-kb band of EcoRI-digested DQ beta, and 6.0-kb band of Taq I digested DQ alpha, because the frequency of DW2 is the lowest in normal control subjects.