PURPOSE: Acute mountain sickness (AMS) is a medical condition that results from exposure to high altitude environments, especially those above 8000 ft (2500 m). Because there are few clear predictors of AMS onset, it is thought that genetic polymorphisms could determine physiological responses to the high altitude environment. One gene implicated in AMS onset is the angiotensin converting enzyme (ACE). ACE is a central component of the renin-angiotensin system (RAS), which controls blood pressure by regulating the volume of body fluids. Specifically, the I-allele of the ACE gene has been associated with high-altitude mountaineering success and lack of AMS development. However, data from the literature are conflicting in that many studies show no difference in I-allele vs. D-allele association and such outcomes. Therefore, we designed and performed a study to investigate the association of ACE genotypes in a population of mountaineers attempting to summit Mt. Rainier, a 14,441 ft glaciated volcano located in Washington State. METHODS: We recruited 29 volunteers at Camp Muir (10,100 ft) that met all of our inclusion criteria. To these participants, we administered a demographics questionnaire, the Lake Louise AMS questionnaire, and we collected DNA using a check swab. We then took the samples back to the laboratory where we isolated the DNA, genotyped each individual for ACE polymorphisms using PCR, and performed statistical analyses on the results. RESULTS: We found that 48.28% of our participants met the Lake Louise criteria for a positive AMS score. Our data showed no significant correlation between reported AMS and age, sex, race, weight, height, body mass index, alcohol use or smoking. Subsequent to genotyping, 20.68% of the participants were found to exhibit the DD genotype, 48.28% the ID genotype, 31.03% the II genotype, and Hardy-Weinberg equilibrium was confirmed (x2= 0.078). However, no significant correlation between DD/ID/II genotypes and AMS was found (x2= 4.985, df=5, p=0.41). Interestingly, we did find an increased, but not significant, representation of the I allele in individuals reporting no AMS symptoms. CONCLUSION: Our data show a higher than expected prevalence of AMS at Camp Muir. As expected, we report no significant correlation between reported AMS symptoms and age, sex, race, weight, height, body mass index, alcohol use, or smoking. Finally, our data suggest that the ID-ACE gene polymorphism does not appear to affect susceptibility to AMS.

Mazamas Mountaineering Organization Research Grant, Pacific Research Institute for Science and Math Summer Research Grant

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