The familial risk and HLA susceptibility among narcolepsy patients in Hong Kong Chinese.
OBJECTIVE
To explore the familial aggregation and HLA susceptibility of narcolepsy in Hong Kong Chinese by objective sleep measurements and HLA typing.


METHODS
Case control design


METHODS
Twelve narcoleptic probands, 34 first-degree relatives, and 30 healthy controls.


METHODS
N/A.


RESULTS
Each subject underwent a standardized nocturnal polysomnogram (PSG), followed by a daytime multiple sleep latency test (MSLT). HLA typing was performed for all subjects. One relative (2.9%) was diagnosed as suffering from narcolepsy with cataplexy. Nearly 30% of the relatives fulfilled the criteria of narcolepsy spectrum disorder (shortened mean sleep latency [MSL] and/or the presence of sleep onset REM periods [SOREMPs]). When using the population data for comparison, the relative risk of narcolepsy in first-degree relatives was 85.3. The odds ratio of narcolepsy spectrum disorder in first-degree relatives was 5.8 (95% CI: 1.2 - 29.3) when compared to healthy controls. There existed 6 multiplex families, in which all 10 relatives with narcolepsy spectrum disorders, including all 3 relatives with multiple SOREMPs, were positive for HLA DQB1*0602.


CONCLUSIONS
Our study demonstrated a definitive familial aggregation of narcolepsy, narcolepsy spectrum disorders, and possibly cataplexy in Hong Kong Chinese. This familial aggregation supported an inherited basis for narcolepsy spectrum. The tight co-segregation of HLA DQB1*0602 and narcolepsy spectrum disorders might suggest that HLA typing, especially DQB1*0602, at least partly confer the familial risk of narcolepsy. In addition, our study suggested that the subjective questionnaire measurements including Ullanlinna Narcolepsy Scale and Epworth Sleepiness Scale were unable to detect the presence of narcolepsy spectrum disorders among the relatives. A stringent objective measurement-based design for family studies is suggested for future study. Further studies are indicated for the determination of the mode and molecular level of narcolepsy transmission.
Chen
Lei
L
Department of Psychiatry, The Chinese University of Hong Kong, Prince of Wales and Shatin Hospitals, Shatin, Hong Kong SAR.
Fong
S Y Y
SY
Lam
Ching W
CW
Tang
Nelson L S
NL
Ng
Margaret H L
MH
Li
Albert M
AM
Ho
C K W
CK
Cheng
Suk-Hang
SH
Lau
Kin-Mang
KM
Wing
Yun Kwok
YK
D000328:Adult; D044466:Asian People / Q000208:ethnology*; D005260:Female; D020022:Genetic Predisposition to Disease; D006680:HLA Antigens / Q000235:genetics*; D006723:Hong Kong; D006801:Humans; D008297:Male; D009290:Narcolepsy / Q000208:ethnology* / Q000235:genetics*; D010375:Pedigree; D017286:Polysomnography; D011159:Population Surveillance; D015995:Prevalence; D012307:Risk Factors; D012894:Sleep Stages / Q000502:physiology
D006680:HLA Antigens