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The Roma people are the largest transnational ethnic minority in Europe and can be considered the last human migration of South Asian origin into the continent. They left Northwest India approximately 1,000 years ago, reaching the Balkan Peninsula around the twelfth century and Romania in the fourteenth century. Here, we analyze whole-genome sequencing data of 40 Roma and 40 non-Roma individuals from Romania. We performed a genome-wide scan of selection comparing Roma, their local host population, and a Northwestern Indian population, to identify the selective pressures faced by the Roma mainly after they settled in Europe. We identify under recent selection several pathways implicated in immune responses, among them cellular metabolism pathways known to be rewired after immune stimulation. We validated the interaction between PIK3-mTOR-HIF-1α and cytokine response influenced by bacterial and fungal infections. Our results point to a significant role of these pathways for host defense against the most prevalent pathogens in Europe during the last millennium., Tis study has been funded by a Spinoza grant of the Netherlands Organization for Scientifc Research (MN), and by BFU2016-77961-P (JB and EBo), PID2019-110933GB-I00 (JB and EBo) and CGL2016-75389-P (DC) (AEI/ FEDER, UE) awarded by the Agencia Estatal de Investigación, CEX2018-000792-M, Unidad de Excelencia María de Maeztu (JB, DC and EBo), and GRC 2017 SGR 702 of Secretaria d’Universitats i Recerca de la Generalitat de Catalunya (JB, EBo and DC). BD is supported by FPU grant FPU13/06813 from the Ministerio de Educación, Cultura y Deporte (Spain). MM was supported by the European Union through the European Regional Development Fund (Project No. 2014-2020.4.01.16-0030)

TRPP3 (also called PKD2L1) is a nonselective, cation-permeable channel activated by multiple stimuli, including extracellular pH changes. TRPP3 had been considered a candidate for sour sensor in humans, due to its high expression in a subset of tongue receptor cells detecting sour, along with its membership to the TRP channel family known to function as sensory receptors. Here, we describe the functional consequences of two non-synonymous genetic variants (R278Q and R378W) found to be under strong positive selection in an Ethiopian population, the Gumuz. Electrophysiological studies and 3D modelling reveal TRPP3 loss-of-functions produced by both substitutions. R278Q impairs TRPP3 activation after alkalinisation by mislocation of H binding residues at the extracellular polycystin mucolipin domain. R378W dramatically reduces channel activity by altering conformation of the voltage sensor domain and hampering channel transition from closed to open state. Sour sensitivity tests in R278Q/R378W carriers argue against both any involvement of TRPP3 in sour detection and the role of such physiological process in the reported evolutionary positive selection past event., Tis work was funded by the Spanish Ministry of Science and Innovation, the State Research Agency (AEI, Agencia Estatal de Investigación) and FEDER Funds (Fondo Europeo de Desarrollo Regional): Grants BFU2016-77961-P to J.B. and E.B., RTI2018-094809-B-I00 to J.M.F.F., PID2019-110933GB-I00/AEI/10.13039/501100011033 to E.B. and J.B., and CEX2018-000792-M through the “María de Maeztu” Programme for Units of Excellence in R&D to “Departament de Ciències Experimentals i de la Salut”. With the support of Secretaria d’Universitats i Recerca del Departament d’Economia i Coneixement de la Generalitat de Catalunya (GRC 2017 SGR 702). S.W. has had a F.P.I. grant (BES-2014-068994) and M.I.-S. a “Juan de la Cierva-Incorporación” Fellowship funded by the Spanish Ministry of Science and Innovation.