Introduction to the study: The RYR1 ion channel disorder is associated with malignant hyperthermia and also with myopathies and with other muscular disorders. Some studies have shown that it is a cause of activity-related muscle pain. This survey study explores the relationship of RYR1 to muscle pain, fatigue and the ability to exercise. Interest in the problems caused by RYR1 mutant variants arose from a consideration that RYR1 variants may cause myofascial pain, or pain related to physical exertion. There has not been an examination of the relationship between RYR1 channelopathy and myofascial pain, although a proposed mechanism for the development of myofascial trigger points suggests that the RYR1 channelopathy is a likely cause of trigger point formation (Gerwin, 2023).  There are over 700 known RYR1 mutations, but only a few of them are known to be associated particles.

This questionnaire study differs from the previous studies in that we are selecting as subjects persons with known RYR1 variants, whether or not they have had malignant hyperthermia or exertional rhabdomyolysis (tea or cola-colored urine), and inquiring about the presence and degree of myalgia, fatigue, and exercise tolerance and habits. We expect to have both subjects who have been symptomatic with malignant hyperthermia and/or exertional rhabdomyolysis and those who are asymptomatic, and to compare them to controls, that is, persons without known RYR1 variants. We included in the survey a question about the presence of muscular knots or tightness, symptoms commonly seen in myofascial trigger point pain. We expect to be able to develop a more comprehensive picture of muscle-related symptoms in this group of patients than has been previously published