Dear Editor,

We read with interest the article by de Andrade et al on the prevalence of fatigue, depression, and physical activity in a cohort of 22 patients with Malignant Hyperthermia Susceptibility (MHS) diagnosed by an In Vitro Contracture Test (IVCT), compared with 13 MHS-negative patients and 22 healthy controls. There were no significant differences between the three groups in terms of fatigue intensity, fatigue associated with specific situations, psychological consequences of fatigue, fatigue response to rest/sleep, depression, number of active/sedentary participants, and the mean time and habitual physical activity characteristics, but physically active MHS patients showed a greater fatigue response to rest/sleep than the sedentary MHS subgroup. The study is compelling but has limitations that should be discussed.