The clinical characteristics of Kleine–Levin syndrome according to ethnicity and geographic location

<p><b>Purpose:</b> Kleine–Levin syndrome (KLS) is a rare, relapsing-remitting, debilitating sleep disorder. Examining KLS characteristics in different ethnic populations may help elucidate the genetic basis of the disorder. No studies have examined KLS in Arabs. Therefore, we compared the clinical characteristics of Saudi Arabian KLS patients to those in other published cohorts to determine whether Arab patients have a distinct phenotype.</p> <p><b>Methods:</b> This study included all patients who were diagnosed with KLS at our center between June 2003 and July 2016 (<i>P</i> = 12; Six familial cases). All participants completed the Stanford KLS questionnaire. Anxiety and depression were assessed using the Hospital Anxiety and Depression Scale; eating attitudes were assessed with the Eating Attitudes Test-26. We compared the clinical characteristics of our patients to those in other published cohorts.</p> <p><b>Results:</b> Saudi Arabian patients with KLS had similar features to those in patients from different countries and ethnic backgrounds, with only minor differences in sleep duration during disease episodes (2–3 h shorter). However, between episodes, Saudi Arabian KLS patients reported worse sleep, greater daytime sleepiness and higher levels of baseline depression, which may be related to KLS or to local cultural practices. Ankylosing spondylitis was present in five of the six familial patients.</p> <p><b>Conclusion:</b> Saudi Arabian patients with KLS exhibited similar clinical characteristics during episodes compared to patients with KLS of different ethnicities. However, a new and interesting finding is that KLS patients may have inter-episode behavioral and pathophysiological changes, which may suggest that KLS is not necessarily a static disorder.</p