What is the reason for the narcolepsy cases developed after H1N1 influenza vaccination?
['The proposed mechanism for postvaccination narcolepsy is one in which an environmental trigger causes or enhances an antibody-mediated autoimmune response in patients with a preexisting genetic susceptibility. ', 'The loss of hypothalamic hypocretin/orexin (hcrt) producing neurons causes narcolepsy with cataplexy. An autoimmune basis for the disease has long been suspected and recent results have greatly strengthened this hypothesis. ', 'pointing towards processes such as molecular mimicry or bystander activation as crucial for disease development. ', 'Although no formal link can be established, the unusual characteristics of the reported cases and the striking temporal relationship suggests that narcolepsy may be the result of an autoimmune reaction triggered by H1N1\xa0vaccination in susceptible individuals.', 'Pandemrix vaccination is a precipitating factor for narcolepsy, especially in combination with HLA-DQB1*0602. ', 'Recently identified autoantibodies to Tribbles homologue 2 in some patients, as well as cases associated with H1N1 vaccination, support an autoimmune mechanism. ', 'n China, narcolepsy onset is highly correlated with seasonal and annual patterns of upper airway infections, including H1N1 influenza. In 2010, the peak seasonal onset of narcolepsy was phase delayed by 6 months relative to winter H1N1 infections, and the correlation was independent of H1N1 vaccination in the majority of the sample.', 'H1N1 vaccination was strongly associated with an increased risk of narcolepsy-cataplexy in both children and adults in France']
['The proposed mechanism for postvaccination narcolepsy is one in which an environmental trigger causes or enhances an antibody-mediated autoimmune response in patients with a preexisting genetic susceptibility.']
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