Chronic mountain sickness (CMS), or Monge disease, represents a state of maladaptation to high-altitude hypoxia in a member of a population acclimatized to high altitudes. CMS is characterized by severe polycythemia and an array of neurologic symptoms, including headache, fatigue, somnolence, and depression. Often, people with CMS suffer from strokes and myocardial infarctions in early adulthood because of increased blood viscosity. Studies have shown that CMS is common in Andeans, found occasionally in Tibetans, and absent from the Ethiopian population living on the East African high-altitude plateau (summary by Zhou et al., 2013). Acute mountain sickness (see pulmonary edema of mountaineers, 178400) is experienced by unacclimatized travelers exposed to high altitude. [from
OMIM]