The association between narcolepsy and human leukocyte antigen HLA- DQB1*06:02 has been established elsewhere but remains to be investigated among Saudi Arabian patients with narcolepsy.
Narcolepsy is strongly associated with the HLA DQB1*0602 allele, and its symptoms stem from destruction of hypocretin-secreting neurons in the hypothalamus.
The cataplectic narcolepsy differed from non-cataplectic narcolepsy by having more rapid eye movement (REM)-related clinical symptoms (more sleep paralysis and sleep-related hallucination) and sleep disturbances (shorter REM latency), as well as tighter association with HLA DQB1*0602.
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.
Although narcolepsy presents one of the tightest associations with a specific human leukocyte antigen (HLA) (DQB1*0602), there is strong evidence that non-HLA genes also confer susceptibility.
We decided to test for the presence of several neuron-specific and organ-specific autoantibodies to see if they were present in HLA DQB1*0602-associated or cataplexy-associated narcolepsy or could serve as a serologic marker of the illness.
These results could be explained by increased disease heterogeneity in the noncataplexy group or by a direct effect of the HLA DQB1*0602 genotype on the clinical expression of narcolepsy.