Refining the South Asian Origin of the Romani people

Background: Recent genetic studies based on genome-wide Single Nucleotide Polymorphism (SNP) data further investigated the history of Roma and suggested that the source of South Asian ancestry in Roma originates most likely from the Northwest region of India. Methods: In this study, based also on genome-wide SNP data, we attempted to refine these findings using significantly larger number of European Roma samples, an extended dataset of Indian groups and involving Pakistani groups into the analyses. Our Roma data contained 179 Roma samples. Our extended Indian data consisted of 51 distinct Indian ethnic groups, which provided us a higher resolution of the population living on the Indian subcontinent. We used in this study principal component analysis and other ancestry estimating methods for the study of population relationships, several formal tests of admixture and an improved algorithm for investigating shared IBD segments in order to investigate the main sources of Roma ancestry. Results: According to our analyses, Roma showed significant IBD sharing of 0.132 Mb with Northwest Indian ethnic groups. The most significant IBD sharings included ethnic groups of Punjab, Rajasthan and Gujarat states. However, we found also significant IBD sharing of 0.087 Mb with ethnic groups living in Pakistan, such as Balochi, Brahui, Burusho, Kalash, Makrani, Pashtun and Sindhi. Conclusion: Our results show that Northwest India could play an important role in the South Asian ancestry of Roma, however, the origin of Romani people might include the area of Pakistan as well.