HLA-DRB1 and Cataplexy: More than 85% of narcolepsy with cataplexy patients have HLA DQB1*0602, which is frequently linked to HLA DRB1*1501, whereas only about 40% of atypical, mild narcolepsy patients without cataplexy have HLA DQB1*0602, indicating greater heterogeneity in narcolepsy without cataplexy [23].