Narcolepsy is an autoimmune disease.
If you type in 'narcolepsy news' to Google it'll come up with various articles about this same study, saying that narcolepsy is an autoimmune disease, related in particular to the similarity between hypocretin (the 'wakefulness' protein) and a protein part of the H1N1 swine flu virus.
The other sentence particle that I also found interesting was 'in genetically susceptible individuals'. To me, this implies that this is not a hereditary disease, just that it is made more likely to appear in people who are genetically susceptible. And it could mean that narcolepsy may eventually be diagnosed by blood test. That's quite amazing, really.
More interesting AGAIN, is the relationship between narcoleptics and histamine. A small study conducted on the brains of cadavers found a 64% increase in histamine neurons in people diagnosed with narcolepsy and cataplexy. Way to science, people! So glad there are people looking into these things... narcolepsy isn't as sexy as breast cancer or as tragically hard hitting as dementia, but it's important and affects people!