In KLS, the association of an infection before the onset of a disease, a young age at onset, a recurrence of symptoms and possible genetic predisposition is suggestive of an autoimmune disease. Various autoimmune diseases are tightly linked to a specific human leukocyte antigen (HLA) typing (this is a group that is not, like group A, B, O, on our red cells, but on our white cells). The immune system indeed distinguishes self-antigens from foreign antigens through the cell surface expression of the highly polymorphic HLA glycoprotein antigens. The HLA system (allele HLA-DQB1*0602) is highly associated with another sleep disorder, narcolepsy. It has been poorly studied in KLS patients, but a recent study in Europe yielded a higher than controls frequency of the HLA-DQB1*201 allele in 30 KLS patients, a group that has been associated with various autoimmune diseases. It is now necessary to extend and specify the measure to a much larger number of patients and families.
Strong evidence for an autoimmune basis in KLS could potentially lead to the testing of drugs or therapy aimed at reducing autoimmunity, which have not been yet, to our knowledge, tested in KLS. This is of particular interest in that severe disease where effective treatment is desperately missing. In addition, the questionnaire will provide the first large survey of the disease and its symptoms. It will also, when compared to questionnaires completed by non-affected healthy subjects, help identify commonalities between patients.