Familial aggregation of narcolepsy.
OBJECTIVE
To determine the familial aggregation of narcolepsy from perspectives of clinical symptomatology, polysomnographic data, and human leukocyte antigen (HLA) typing.


METHODS
This was a Family study at the University-affiliated hospital. The participants were narcolepsy probands and their first degree relatives, and, also, age and sex matched unrelated healthy controls. Interventions were not applicable.


RESULTS
All study subjects underwent structured interviews, overnight polysomnography followed by a multiple sleep latency test (MSLT), and HLA typing. Altogether, 33 probands and 81 first degree relatives (response rate 65%) were recruited. Among the relatives, 12.3% were diagnosed with narcolepsy and 39.5% had narcolepsy spectrum as defined by unexplained abnormal MSLT (shortened MSL and SOREMP) results. The relative risk of narcolepsy in first degree relatives was 361.8. Familial aggregation of narcolepsy symptoms, excessive daytime sleepiness, HLA status, abnormal MSLT, and nocturnal polysomnographic findings were observed.


CONCLUSIONS
The familial risk of narcolepsy among first degree relatives is much higher than previously reported. There exists a spectrum of narcolepsy features among relatives, ranging from full clinical tetrads to asymptomatic abnormal MSLT findings.
Department of Psychiatry, The Chinese University of Hong Kong, Shatin, Hong Kong. ykwing@cuhk.edu.hk
Yun-Kwok
YK
Wing
Lei
L
Chen
Siu-Ping
SP
Lam
Albert M
AM
Li
Nelson L S
NL
Tang
Margaret H L
MH
Ng
Suk-Hang
SH
Cheng
Crover K W
CK
Ho
V
V
Mok
Ho-Wan
HW
Leung
Alexander
A
Lau
Michael Ho-Ming
MH
Chan
Hiu-Shuen
HS
Chan
Paul S K
PS
Chan
D000293:Adolescent; D000328:Adult; D002648:Child; D005190:Family; D005192:Family Health / Q000706:statistics & numerical data*; D005260:Female; D059866:HLA-DQ beta-Chains / Q000235:genetics*; D006650:Histocompatibility Testing; D006801:Humans; D008297:Male; D009290:Narcolepsy / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D017286:Polysomnography; D015995:Prevalence; D012307:Risk Factors; D055815:Young Adult
D059866:HLA-DQ beta-Chains; C069051:HLA-DQB1 antigen