Genetics of High Altitude Life
Almost every biological anthropology text-book I’ve ever looked at has described the adaptations of human populations to the environments they occupy. Examples they give are the short stalky Inuit adapted to conserving heat in cold environments, the long lanky East African nomads adapted to far distant travels, and the barrel chested Peruvian and Tibetans living in low oxygen environments.
Highland Tibet
Little discussion, beyond correlating ecology and physical observation, is given to these. Actually I lie, the physiology of the barrel chested high altitude occupants is given a couple of sentences as well as an elevated oxygen binding capacity without concentrating their blood.
A paper published in Science several days ago tackles this latter issue. A group of scientists looked for unique alleles among Tibet highlanders and discovered 10 unique oxygen-processing alleles. I don’t have full access to the publication, so can’t tell if these genes encode for completely different functioning proteins or are differentially regulated at high altitudes.
All I can derive is that these genes seem to prevent polycythemia, edematous swelling of the lungs and brain, and hypertension of the pulmonary vasculature, which are all complications of high altitude living. Two of these genes are EGLN1 and PPARA. PPARA is a peroxisome proliferation proteins that also is a leukotriene antagonist. That is interesting because in obstructive conditions like asthama, leukotrienes induce vasospasm and bronchconstriction. EGLN1 is also has an interesting role,
“it is a protein encoded by this gene catalyzes the post-translational formation of 4-hydroxyproline in hypoxia-inducible factor (HIF) alpha proteins. HIF is a transcriptional complex that plays a central role in mammalian oxygen homeostasis.”
These two genes were significantly associated with the decreased hemoglobin phenotype that is unique to this highland population.
- Simonson TS, Yang Y, Huff CD, Yun H, Qin G, Witherspoon DJ, Bai Z, Lorenzo FR, Xing J, Jorde LB, Prchal JT, & Ge R (2010). Genetic Evidence for High-Altitude Adaptation in Tibet. Science (New York, N.Y.) PMID: 20466884
More UV and vitamin D at high altitude as well.
UV increased by 4% for every 1000 foot of altitude
See the health benefits of UV and vitamin D at VitaminDWiki
Henry Lahore
May 22, 2010 at 7:48 am
What is your source on UV increasing by 4% for every 1000 foot of altitude? I am trying to find information on the solar spectrum at high altitudes.
If you could email me where you found this info, I would really appreciate it.
Noura Howell
July 14, 2010 at 11:20 pm
Interesting, however only EGLN1 AND EPAS1 have been consecutively found in genome wide scans, and are associated with hemoglobin levels, and with altitude, higher fequency of haplotype variants with altitude. This study that did not find EPAS1, read Xu et al, 2010/11 it describes this. The link to Hb may provide a functional variant that lowers Hb, which studies such as Gustavo et al., 2009 say are linekd to better outcoems in pregancy. I for one believe that EPAS1 has EGLN1 have hidden effects in utero during pregnancy that may protect birth weight at alitude, remember ancestry protects bbirth weight at alittude, Tibetans have less IUGR than andeans who have less than han who have less than europeans. I for one think EPAS1 is linked to less repiratory distress and ease of first breath in Tibetan infants, due state of surfacant, HIF2a related to vegf and surfucant, knockout hif2a less surfucant and vegf, exogenous vegf gives surfucant. Nieymeyer et al., 2004 decribes this, persisten fetal ciruclations whcih would likely effect o2 saturation first 4 months and HPV. Also may have affect on nitric oxide levels, fucntional assays have to be done. and retrospective or prospective studies linking genes to these variables.
Interesting also that PEAS1 may have role in retinopathy, due to its role angiogensis retinal devlopment, may protect in alititude. UC related blindness.
ProfdoC
April 27, 2011 at 1:53 pm