Emmanuel Mignot, MD, PhD, is one of the pioneers in the study of narcolepsy and served a vital role in discerning the genetic cause of this rare and underdiagnosed disorder. Dr. Mignot, Professor of Sleep Medicine in the Department of Psychiatry and Behavioral Sciences, Stanford University, recently shared his thoughts on his work with CheckRare.
Dr. Mignot, who earned his medical degree with a specialty in psychiatry in Paris, moved to the US at age 27, intending to teach pharmacology after earning his PhD. As part of his work, he studied the pharmacodynamics of modafinil in dogs with narcolepsy. The experience changed his professional focus.
Working with this animal model, his research sought to identify a genetic cause of narcolepsy type 1, and was successful in isolating it in 1999. The gene was responsible for regulating orexin, a hormone that also regulates appetite. “[The discovery] and the publication in the journal Cell put narcolepsy on the map. It was not the orexin receptors that was the problem, it was the ligands attaching to orexin. We developed a test for it, which really helped pinpoint the diagnosis,” said Dr. Mignot.
Diagnosing narcolepsy is really a two-pronged problem, he commented. First, the patient doesn’t reveal all of the symptoms and signs (as they tend to normalize them) and second, the physicians have difficulty pinpointing the diagnosis. “In many cases, the patients get used to their cataplexy episodes or don’t want to admit having them,” commented Dr. Mignot, so they don’t bring them up to the doctor. On the other hand, the primary care physicians rarely see patients with narcolepsy type 1, and they fail to question patients about cataplexy episodes. In addition, the patient can mistakenly be diagnosed as having seizures or other unrelated disorders. For young patients, “this is a tragedy,” he said, “because it so negatively affects their childhood and their education.”
In the past, patients with narcolepsy type 1 were treated with antidepressants and stimulants, before sodium oxybate was introduced. Current pharmacotherapy is still largely focused on symptomatic treatment, but the investigational orexin-2 agonists may be truly disease modifying. Clinical studies with these agents show “how much improved their condition is, over the medications. With this medication, [study patients] feel kind of normal,” stated Dr. Mignot.
Many important questions remain to be answered, such as how to cure the condition or at least prevent it. There is evidence that there is an immune response that triggers the attack on orexin-producing neurons. Dr. Mignot stated, “We have evidence that it is triggered by the flu,” and if we understood the mechanism of this autoimmune attack, we might be able to modify flu vaccines in the preventive effort.
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