RT Journal Article SR Electronic T1 Evolution of Hominin Polyunsaturated Fatty Acid Metabolism: From Africa to the New World JF bioRxiv FD Cold Spring Harbor Laboratory SP 175067 DO 10.1101/175067 A1 Daniel N. Harris A1 Ingo Ruczinski A1 Lisa R. Yanek A1 Lewis C. Becker A1 Diane M. Becker A1 Heinner Guio A1 Tao Cui A1 Floyd H. Chilton A1 Rasika A. Mathias A1 Timothy D. O’Connor YR 2017 UL http://biorxiv.org/content/early/2017/08/10/175067.abstract AB Background The metabolic conversion of dietary omega-3 and omega-6 18 carbon (18C) to long chain (> 20 carbon) polyunsaturated fatty acids (LC-PUFAs) is vital for human life. Fatty acid desaturase (FADS) 1 and 2 catalyze the rate-limiting steps in the biosynthesis of LC-PUFAs. The FADS region contains two haplotypes; ancestral and derived, where the derived haplotypes are associated with more efficient LC-PUFA biosynthesis and is nearly fixed in Africa. In addition, Native American populations appear to be nearly fixed for the lesser efficient ancestral haplotype, which could be a public health problem due to associated low LC-PUFA levels, while Eurasia is polymorphic. This haplotype frequency distribution is suggestive of archaic re-introduction of the ancestral haplotype to non-African populations or ancient polymorphism with differential selection patterns across the globe. Therefore, we tested the FADS region for archaic introgression or ancient polymorphism. We specifically addressed the genetic architecture of the FADS region in Native American populations to better understand this potential public health impact.Results We confirmed Native American ancestry is nearly fixed for the ancestral haplotype and is under positive selection. The ancestral haplotype frequency is also correlated to Siberian populations’ geographic location further suggesting the ancestral haplotype’ s role in cold weather adaptation and leading to the high haplotype frequency within Native American populations’. We also find that the Neanderthal is more closely related to the derived haplotypes while the Denisovan clusters closer to the ancestral haplotypes. In addition, the derived haplotypes have a time to the most recent common ancestor of 688,474 years ago which is within the range of the modern-archaic hominin divergence.Conclusions These results support an ancient polymorphism forming in the FADS gene region with differential selection pressures acting on the derived and ancestral haplotypes due to the old age of the derived haplotypes and the ancestral haplotype being under positive selection in Native American ancestry populations. Further, the near fixation of the less efficient ancestral haplotype in Native American ancestry suggests the need for future studies to explore the potential health risk of associated low LC-PUFA levels in Native American ancestry populations.AbbreviationsALA =α–linolenic acidARA =arachidonic acidC =carbonCI =confidence intervalDHA =docosahexaenoic acidDPA =docosapentaenoic acidEPA =eicosapentaenoic acidFADS =fatty acid desaturaseLA =linoleic acidLC =long chainMWD =modern western dietn3 =omega-3n6 =omega-6PUFA =polyunsaturated fatty acidTMRCA =time to the most recent common ancestorya =years ago