Previous genetic, anthropological and linguistic studies have shown that Roma (Gypsies) constitute a founder population dispersed throughout Europe whose origins might be traced to the Indian subcontinent. Linguistic and anthropological evidence point to Indo-Aryan ethnic groups from North-western India as the ancestral parental population of Roma. Recently, a strong genetic hint supporting this theory came from a study of a private mutation causing primary congenital glaucoma. In the present study, complete mitochondrial control sequences of Iberian Roma and previously published maternal lineages of other European Roma were analyzed in order to establish the genetic affinities among Roma groups, determine the degree of admixture with neighbouring populations, infer the migration routes followed since the first arrival to Europe, and survey the origin of Roma within the Indian subcontinent. Our results show that the maternal lineage composition in the Roma groups follows a pattern of different migration routes, with several founder effects, and low effective population sizes along their dispersal. Our data allowed the confirmation of a North/West migration route shared by Polish, Lithuanian and Iberian Roma. Additionally, eleven Roma founder lineages were identified and degrees of admixture with host populations were estimated. Finally, the comparison with an extensive database of Indian sequences allowed us to identify the Punjab state, in North-western India, as the putative ancestral homeland of the European Roma, in agreement with previous linguistic and anthropological studies.

IM was supported by a fellowship by the Basque Government (Hezkuntza, Unibertsitate eta Ikerketa Saila, Eusko Jaurlaritza, BFI107.4). Fundaçao para a Ciencia e Tecnologia (FCT) supported CV, VG, AG and LA through grants SFRH/BD/63343/2009, SFRH/BD/36045/2007, SFRH/BPD/43646/2008 and SFRH/BPD/65000/2009, respectively. This work was partially financed by FCT through project PTDC/AN /70413/2006 and POCI 2010, Programa Operacional Ciencia e Inovaçao; Dirección General de Investigación, Ministerio de Educación y Ciencia, Spain (CGL2009-14944/BOS); Direcció General de Recerca, Generalitat de Catalunya (2009SGR1101) and the Austrian Science Fund (FWF): TR397. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript