title: Combining sperm typing and linkage disequilibrium analyses reveals differences in selective pressures or recombination rates across human populations.
abstract: A previous polymorphism survey of the type 2 diabetes gene CAPN10 identified a segment showing an excess of polymorphism levels in all population samples, coinciding with localized breakdown of linkage disequilibrium (LD) in a sample of Hausa from Cameroon, but not in non-African samples. This raised the possibility that a recombination hotspot is present in all populations and we had insufficient power to detect it in the non-African data. To test this possibility, we estimated the crossover rate by sperm typing in five non-African men; these estimates were consistent with the LD decay in the non-African, but not in the Hausa data. Moreover, resequencing the orthologous region in a sample of Western chimpanzees did not show either an excess of polymorphism level or rapid LD decay, suggesting that the processes underlying the patterns observed in humans operated only on the human lineage. These results suggest that a hotspot of recombination has recently arisen in humans and has reached higher frequency in the Hausa than in non-Africans, or that there is no elevation in crossover rate in any human population, and the observed variation results from long-standing balancing selection.
authors.affiliation: Department of Human Genetics, University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Vanessa J
authors.initials: VJ
authors.lastname: Clark
authors.forename: Susan E
authors.initials: SE
authors.lastname: Ptak
authors.forename: Irene
authors.initials: I
authors.lastname: Tiemann
authors.forename: Yudong
authors.initials: Y
authors.lastname: Qian
authors.forename: Graham
authors.initials: G
authors.lastname: Coop
authors.forename: Anne C
authors.initials: AC
authors.lastname: Stone
authors.forename: Molly
authors.initials: M
authors.lastname: Przeworski
authors.forename: Norman
authors.initials: N
authors.lastname: Arnheim
authors.forename: Anna
authors.initials: A
authors.lastname: Di Rienzo
mesh_terms: D000818:Animals; D020029:Base Pairing; D001483:Base Sequence; D044383:Black People / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D015810:Linkage Disequilibrium / Q000235:genetics*; D008297:Male; D008957:Models, Genetic; D002679:Pan troglodytes / Q000235:genetics; D011110:Polymorphism, Genetic; D011995:Recombination, Genetic / Q000235:genetics*; D012641:Selection, Genetic; D013094:Spermatozoa / Q000145:classification* / Q000378:metabolism*