Narcolepsy in Southern Chinese- Clinical Characteristics, HLA Typing and Seasonality of Birth

Wing YK ^1*, Chen L ¹, Fong SYY ¹, Ng MHL ¹, Ho CKW ¹, Cheng SH ¹, Tang NLS ¹ and Li AM ¹

¹ The Chinese University of Hong Kong, Hong Kong

^* To whom correspondence should be addressed. E-mail: ykwing{at}cuhk.edu.hk.

Accepted 8 March 2008

Abstract

Objective: To report clinical characteristics, HLA typing and seasonality of birth of a series of fifty-four Southern Chinese suffering from narcolepsy.

Methods: All subjects underwent detailed medical and psychiatric interviews and a standardized nocturnal PSG followed by a daytime MSLT. Each subject also completed a set of sleep questionnaires. HLA typing was performed in 91% of subjects.

Results: Seventy-eight percent and 22% were diagnosed of suffering from cataplectic and non-cataplectic narcolepsy respectively. Majority (n=47, 87%) of patients were referred to our sleep clinic for EDS. The cataplectic narcolepsy differed from non-cataplectics by having more REM-related clinical (more Sleep Paralysis and Sleep-related Hallucination) and sleep disturbances (shorter REM latency) as well as tighter association with HLA DQB1*0602. A bi-modal peak pattern was observed at 11 years and 39 years old. Similar bi-modal pattern also occurred for EDS and cataplexy. Excess winter birth was observed for this series of patients. Eighty-one percent of cataplectic narcolepsy patients were DQB1*0602 positive. There were no difference between early and late onset cases in the association with positive DQB1*0602 (71.4% vs 60%). Narcolepsy has prominent pernicious effects on various social, academic, family and mental aspects in our patients.

Conclusions: In our Southern Chinese narcolepsy series, bi-modal peak pattern of age of onset, excess winter birth and tight association of HLA DQB1*0602 with cataplectic narcolepsy were found.