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Genetic Evidence for High-Altitude Adaptation in Tibet - Coggle Diagram
Genetic Evidence for High-Altitude Adaptation in Tibet
Abstract
Tibetians have lived at high altitudes for several years and can tolerate a low-oxygen environment
Genes EGLN1 and PPARA have been associated with these traits
These genes support a hypothesis about oxygen pathways in humans
Conclusion
Diminished Hb levels
found in Tibetans offset complications associated with high Hb levels
Decreased Hb levels could be side effect of other phenotypes that are targets of natural slection
Functional analysis of EGLN1 and PPARA will increase understanding of genetic adaptation to high-altitude
environments
Important for understanding how to treat diseases related to hypoxia
Mountain sickness
High-altitude pulmonary and cerebral edema
Intro
Home to an extreme environment, Tibetians have had to endure high-altitudes since the mid-Holocene era.
Distinct traits
Decreased arterial oxygen content
Increased resting ventilation
Reduced hemoglobin concentration
Lack of hypoxic pulmonary vasoconstriction
Lower incidence of reduced birth weight
Tibetians maintain normal aerobic metabolism even in such low-oxygen environment
Experimental Study
Candidates for adaptation to
high-altitude hypoxia were chosen
Candidates associated with distinct traits merged with Panther pathway (Hypoxia response via HIF)
A genome wide scan was conducted
Alleles were identified subject to strong
recent positive selection in a sample of unrelated Tibetians
Individuals showed
no evidence of blending with neighboring populations
Results
High-altitude adaptation in Tibetans has resulted from local positive
selection on several distinct genes
The haplotypes of
EGLN1 and PPARA both show significant negative correlations with Hb concentration
Provides evidence of a genetic contribution to a form of high-altitude adaptation that appears to be unique to Tibetan populations
PPARA interacts with components of HIF pathway