High-altitude adaptation

High-altitude adaptation comprises inherited or acquired traits that help organisms function where low oxygen, cold, and intense ultraviolet radiation impose physiological stress.

Hypoxia: A condition in which tissues receive too little oxygen for their needs. Low oxygen pressure at elevation causes the central physiological challenge adaptations must address.
Tibetan high-altitude adaptation: Inherited traits that help Tibetan populations live and reproduce at high elevations. Tibetans commonly maintain relatively low hemoglobin concentrations despite chronic hypoxia.
EPAS1: A gene encoding a transcription factor involved in cellular responses to low oxygen. Variants near EPAS1 are strongly associated with the characteristic Tibetan response to altitude.
Acute mountain sickness: A syndrome of headache and other symptoms that can develop after ascent to high altitude. It affects newcomers before longer-term acclimatization can reduce symptoms.
Erythropoietin: A hormone that stimulates red blood cell production in response to reduced oxygen availability. Its signaling helps explain why some high-altitude populations produce fewer extra red blood cells.
Andean high-altitude adaptation: Inherited physiological traits found in populations long resident in the Andes. Many Andean highlanders respond to hypoxia with increased hemoglobin and enlarged lung capacity.
EGLN1: A gene encoding an enzyme that helps regulate the body’s response to oxygen availability. EGLN1 variants contribute to Tibetan high-altitude adaptation through oxygen-sensing pathways.
High-altitude pulmonary edema: A potentially life-threatening accumulation of fluid in the lungs after ascent to high altitude. It shows how a hypoxic vascular response can become dangerous rather than beneficial.
Hemoglobin: The oxygen-binding protein in red blood cells that transports oxygen through vertebrate blood. Changes in hemoglobin’s oxygen affinity can alter oxygen uptake in thin air.
Ethiopian high-altitude adaptation: Inherited traits that support life at high elevation in Ethiopian populations. Ethiopian highlanders often show neither the high hemoglobin pattern of Andeans nor the Tibetan pattern.

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