The most recent epoch in genetic research has encompassed the analysis of uniparental markers (mitochondrial DNA and Y chromosome), as well as different loci on autosomal chromosomes. The knowledge obtained by this research confirmed the 200 year-old hypothesis first made by linguists (Liégeois 1989, Fraser 1998, Kendrick and Puxon 1998) that, in spite of the variations in numerous Romani groups, they are all descendants of the original proto-Roma population originating in India (Gresham et al. 2001, Morar et al. 2004, Malyarchuk et al. 2006, Kalaydjieva et al. 2005, Mendizabal et al. 2012). The most recent research on Y chromosome (Rai et al. 2012) and the whole genome (Moorjani et al. 2013) place this original Indian population in north-western India, just as the first linguistic research did.
Besides this, the genetic research has provided a more profound insight into the relationships between different Romani groups with the surrounding majority populations. It has shown that the Romani people have remained genetically (as well as socially and culturally) isolated from the surrounding populations, although a certain degree of admixture has been observed. E.g. in Croatia, 50.3% of Romani men have haplotypes of Y chromosome that reveal their Indian origin (Martinović Klarić et al. 2008), while 26.5% of Romani men and women have mitochondrial haplogroup M, characteristic for the Indian subcontinent (Peričić Salihović et al. 2011). Similar data have been obtained for other European countries (Mendizabal et al. 2011, Gusmao et al. 2008).
The genetic structure of the Roma groups present today in Europe point to relative homogeneity of the entire Roma population, which is manifested in rare Mendelian diseases caused mostly by private mutations (Morar et al. 2004). The homogeneous genetic structure is the result of the genetic drift – limited gene flow from the surrounding majority populations and the founder effect in the formation of new Roma groups, leading to the development of isolates within the isolates and accumulation of mutations which lead to the occurrence of specific hereditary diseases (Kalaydjieva et al. 2001b). However, despite homogeneity at the entire Roma population level, there is a clear differentiation between specific groups (Gresham et al. 2001, Chaix et al. 2004, Kalaydjieva et al. 2005). The comparison of several autosomal loci points to the internal diversity of the Roma people, which are far more heterogeneous than the autochthonous European populations (Kalaydjieva et al. 2001a, Chaix et al. 2004). Use of genetics enabled us to have a better insight into the practice of inbreeding, which proved to be quite extensive compared to other populations (Malyarchuk et al. 2006).
In addition to this, recent research on mitochondrial DNA of several European Roma groups has clearly pointed to different migratory routes and different patterns in individual Roma groups namely, it has indicated the separation of the Vlachs from the Balkan and Western European Roma that arrived in Europe during the first migration wave (Mendizabal et al. 2011, Peričić Salihović et al. 2011). Similar results were obtained using autosomal chromosome research (Novokmet and Pavcec 2007, Gusmão et al. 2010) and microsatellite chromosome Y (Novokmet and Pavcec 2007, Gusmão et al. 2008, Martinović Klarić et al. 2008, Rai et al). The studies of monogenic diseases specific to the Roma population (Kalaydjieva et al. 1996, Piccolo et al. 1996, Abicht et al. 1999) have confirmed that these migration patterns are also reflected in the distribution of mutations and different carrier rates in the investigated Roma populations (Morar et al. 2004).
In addition to these insights, the limited variability of maternal and paternal hereditary lines suggests that the Roma originated from a small number of founders who had separated from the ancestral Indian population (Kalaydjieva and Morar 2003) and later further split into many different subgroups which started differentiating between each other (Kalaydjieva et al. 2005). As a consequence of this, it is possible to detect the reflection of the processes such as the founder effect, the bottleneck and the genetic drift due to reduction in population size in the profiles of specific Roma groups.