Veyrunes F. auteur aut IRD Chevret P. auteur aut IRD Catalan J. auteur aut IRD Castiglia R. auteur aut IRD Watson J. auteur aut IRD Dobigny Gauthier auteur aut IRD Robinson T. J. auteur aut IRD Britton Davidian J. auteur aut IRD text journalArticle eng text/pdf born digital access Therian mammals have an extremely conserved XX/XY sex determination system. A limited number of mammal species have, however, evolved to escape convention and present aberrant sex chromosome complements. In this study, we identified a new case of atypical sex determination in the African pygmy mouse Mus minutoides, a close evolutionary relative of the house mouse. The pygmy mouse is characterized by a very high proportion of XY females (74%, n = 27) from geographically widespread Southern and Eastern African populations. Sequencing of the high mobility group domain of the mammalian sex determining gene Sry, and karyological analyses using fluorescence in situ hybridization and G-banding data, suggest that the sex reversal is most probably not owing to a mutation of Sry, but rather to a chromosomal rearrangement on the X chromosome. In effect, two morphologically different X chromosomes were identified, one of which, designated X*, is invariably associated with sex-reversed females. The asterisk designates the still unknown mutation converting X*Y individuals into females. Although relatively still unexplored, such an atypical sex chromosome system offers a unique opportunity to unravel new genetic interactions involved in the initiation of sex determination in mammals. specialized African pygmy mouse Mus minutoides atypical sex determination system sex-reversed females Sry gene X* chromosome 080 277 1684 1049-1056 2010 0962-8452 https://www.documentation.ird.fr/hor/fdi:010049329 10.1098/rspb.2009.1925 0962-8452 [F B010049329] https://www.documentation.ird.fr/hor/fdi:010049329 https://www.documentation.ird.fr/intranet/publi/2010/03/010049329.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2010-04-06 2017-08-23 fdi:010049329 fre