Percent of oxygen saturation of arterial hemoglobin among Bolivian Aymara at 3,900-4,000 m

Abstract

A range of variation in percent of oxygen saturation of arterial hemoglobin (SaO2) among healthy individuals at a given high altitude indicates differences in physiological hypoxemia despite uniform ambient hypoxic stress. In populations native to the Tibetan plateau, a significant portion of the variance is attributable to additive genetic factors, and there is a major gene influencing SaO2. To determine whether there is genetic variance in other high-altitude populations, we designed a study to test the hypothesis that additive genetic factors contribute to phenotypic variation in SaO2 among Aymara natives of the Andean plateau, a population geographically distant from the Tibetan plateau and with a long, separate history of high-altitude residence. The average SaO2 of 381 Aymara at 3,900-4,000 m was 92+/-0.15% (SEM) with a range of 84-99%. The average was 2.6% higher than the average SaO2 of a sample of Tibetans at 3,800-4,065 m measured with the same techniques. Quantitative genetic analyses of the Aymara sample detected no significant variance attributable to genetic factors. The presence of genetic variance in SaO2 in the Tibetan sample and its absence in the Aymara sample indicate there is potential for natural selection on this trait in the Tibetan but not the Aymara population.

Prevalence of oxygen desaturation and use of oxygen at home in adults at sea level and at moderate altitude

“…The oximeter was attached to the subject's right index finger and all subjects were seated and breathing room air when the measurement was taken. The average of six measurements taken at 10-s intervals [16] was reported, on the condition that a good pulse signal was present (identified by a green flashing light in the device). The accuracy of five of the pulse oximeters used in the study was tested on all five fingers of one hand of 96 patients whose arterial blood gas was analysed by the pulmonary laboratory of the National Institute of Respiratory Diseases in Mexico City (mean¡SD arterial oxygen saturation (Sa,O 2 ) of 87.2¡11%).…”

Higher offspring survival among Tibetan women with high oxygen saturation genotypes residing at 4,000 m

“…The present study in a large sample from three counties in the Tibet Autonomous Region confirmed previous findings of a major gene for oxygen saturation (1,2). It extended those observations by addressing consequences of the genetic variation on measures of Darwinian fitness.…”

“…Tibetans at a given high altitude vary widely in percent oxygen saturation of hemoglobin despite uniform ambient hypoxic stress. A putative major gene (an inferred locus) with a recognizable quantitative effect having an autosomal dominant mode of inheritance that is associated with Ϸ6% higher oxygen saturation has been detected in two areas of the Tibet Autonomous Region (1,2). The high oxygen saturation genotypes may have greater Darwinian fitness because they are less physiologically stressed, in the sense of having higher arterial oxygen content and less departure from the internal milieu that evolved at sea level.…”

Human high-altitude adaptation: forward genetics meets the HIF pathway

“…This is due in part to their increased SaO 2 levels, where Andeans maintain higher levels of SaO 2 at rest and during exercise compared with sea-level inhabitants measured at the same altitude (Brutsaert et al 2000). Tibetan highlanders also exhibit higher levels of SaO 2 compared with low-altitude residents measured at the same altitude (Wu and Kayser 2006), but their average SaO 2 levels at rest are not significantly different from Han Chinese born and raised at high-altitude and are lower than those observed among Andeans when measured using the same equipment and protocol (Beall et al 1997b(Beall et al , 1999Weitz and Garruto 2007). Notably, among Tibetan women, a major autosomal dominant allele for high SaO 2 has been identified in which women carrying the high oxygen saturation allele exhibit a greater offspring survival rate than women possessing the low oxygen saturation allele (Beall et al 1994).…”