title: Genetic landscape of populations along the Silk Road: admixture and migration patterns.
abstract: BACKGROUND
  The ancient Silk Road has been a trading route between Europe and Central Asia from the 2(nd) century BCE to the 15(th) century CE. While most populations on this route have been characterized, the genetic background of others remains poorly understood, and little is known about past migration patterns. The scientific expedition "Marco Polo" has recently collected genetic and phenotypic data in six regions (Georgia, Armenia, Azerbaijan, Uzbekistan, Kazakhstan, Tajikistan) along the Silk Road to study the genetics of a number of phenotypes.
  
  
  RESULTS
  We characterized the genetic structure of these populations within a worldwide context. We observed a West-East subdivision albeit the existence of a genetic component shared within Central Asia and nearby populations from Europe and Near East. We observed a contribution of up to 50% from Europe and Asia to most of the populations that have been analyzed. The contribution from Asia dates back to ~25 generations and is limited to the Eastern Silk Road. Time and direction of this contribution are consistent with the Mongolian expansion era.
  
  
  CONCLUSIONS
  We clarified the genetic structure of six populations from Central Asia and suggested a complex pattern of gene flow among them. We provided a map of migration events in time and space and we quantified exchanges among populations. Altogether these novel findings will support the future studies aimed at understanding the genetics of the phenotypes that have been collected during the Marco Polo campaign, they will provide insights into the history of these populations, and they will be useful to reconstruct the developments and events that have shaped modern Eurasians genomes.
authors.affiliation: Institute for Maternal and Child Health - IRCCS "Burlo Garofolo", Trieste, Italy. massimo.mezzavilla@burlo.trieste.it.|Department of Medical Sciences, University of Trieste, Trieste, Italy. massimo.mezzavilla@burlo.trieste.it.
authors.forename: Massimo
authors.initials: M
authors.lastname: Mezzavilla
authors.affiliation: Institute for Maternal and Child Health - IRCCS "Burlo Garofolo", Trieste, Italy. diego.vozzi@burlo.trieste.it.
authors.forename: Diego
authors.initials: D
authors.lastname: Vozzi
authors.affiliation: Department of Medical Sciences, University of Trieste, Trieste, Italy. nicola.pirastu@burlo.trieste.it.
authors.forename: Nicola
authors.initials: N
authors.lastname: Pirastu
authors.affiliation: Department of Medical Sciences, University of Trieste, Trieste, Italy. giorgia.girotto@burlo.trieste.it.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Girotto
authors.affiliation: Department of Medical Sciences, University of Trieste, Trieste, Italy. pio.dadamo@burlo.trieste.it.
authors.forename: Pio
authors.initials: P
authors.lastname: d'Adamo
authors.affiliation: Institute for Maternal and Child Health - IRCCS "Burlo Garofolo", Trieste, Italy. paolo.gasparini@burlo.trieste.it.|Department of Medical Sciences, University of Trieste, Trieste, Italy. paolo.gasparini@burlo.trieste.it.
authors.forename: Paolo
authors.initials: P
authors.lastname: Gasparini
authors.affiliation: Institute of Genetics and Biophysics 'A. Buzzati-Traverso', National Research Council (CNR), via Pietro Castellino 111, 80131, Naples, Italy. vincenza.colonna@igb.cnr.it.
authors.forename: Vincenza
authors.initials: V
authors.lastname: Colonna
mesh_terms: D044466:Asian People / Q000235:genetics; D017517:Commonwealth of Independent States; D051456:Gene Flow; D006720:Homozygote; D063426:Human Migration; D006801:Humans; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D025341:Principal Component Analysis; D017422:Sequence Analysis, DNA; D044465:White People / Q000235:genetics