Reconstructing the Origins and Migrations of Diasporic Populations: The Case of the European Gypsies

The genetic footprint of the European Roma diaspora: evidence from the Balkans to the Iberian Peninsula

The Roma people have a complex demographic history shaped by their recent dispersal from a South Asian origin into Europe, accompanied by continuous population bottlenecks and gene flow. After settling in the Balkans around 1,000 years ago, the Roma gradually dispersed across Europe, and approximately 500 years ago, they established in the Iberian Peninsula what is now one of the largest Roma populations in Western Europe. Focusing specifically on the Iberian Roma, we conducted the most comprehensive genome-wide analysis of European Roma populations to date. Using allele frequency and haplotype-based methods, we analysed 181 individuals to investigate their genetic diversity, social dynamics, and migration histories at both continental and local scales. Our findings demonstrate significant gene flow from populations encountered during the Roma's dispersal and confirm their South Asian origins. We show that, between the 14th and 19th centuries, the Roma spread westward from the Balkans in various waves, with multiple admixture events. Furthermore, our findings refute previous hypotheses of a North African dispersal route into Iberia and genetic connections to Jewish populations. The Iberian Roma exhibit ten times greater genetic differentiation compared to non-Roma Iberians, indicating significant regional substructure. Additionally, we provide the first genetic evidence of assortative mating within Roma groups, highlighting distinct mating patterns and suggesting a gradual shift towards increased integration with non-Roma individuals. This study significantly enhances our understanding of how demographic history and complex genetic structure have shaped the genetic diversity of Roma populations, while also highlighting the influence of their evolving social dynamics.

Paternal genetic structure of the Bosnian-Herzegovinian Roma: A Y-chromosomal STR study

OBJECTIVES

Studies indicate the complex nature of the genetic structure of the European Roma which has been shaped by different effects of their demographic history, while preserving their ancestral Indian origin. The primary aims of this study were to present for the first time the paternal profiles of the Roma from Bosnia and Herzegovina based on the data from Y-chromosome STR loci, identify the components of non-Roma paternal gene flow into the Roma, and evaluate the genetic relationships with other European Roma populations.

MATERIALS AND METHODS

In this study, 110 DNA samples of unrelated males from Roma populations residing in different regions of Bosnia and Herzegovina were genotyped using the 23 Y-STR loci included in the PowerPlex Y23 system.

RESULTS

The analysis of the genetic structure of the Bosnian-Herzegovinian Roma revealed intra-country population substructuring and indicated differing genetic affinities between the Bosnian-Herzegovinian Roma and other European Roma populations. The paternal genetic structure of the Bosnian-Herzegovinian Roma has two components: an ancestral component represented by haplogroup H1a1a-M82, and European component presented by haplogroups I1-M253, I2a1a2b-L621, J2a1a-L26, J2a1a1a2b2a3~Z7671, J2b2a-M241, G2a2b2a1a1b-L497, and E1b1b-M215.

CONCLUSION

Genetic relations between the Bosnian-Herzegovinian Roma and other European Roma are shaped by different influences on their demographic history. The data suggest that the paternal gene pool of the Roma from Bosnia and Herzegovina might be a consequence of an early separation of the proto-Roma population and the later gene flow as well as factors of the isolation that accompany the Roma populations in some Bosnian-Herzegovinian regions.

Dietary Profile and Nutritional Status of the Roma Population Living in Segregated Colonies in Northeast Hungary

Nutrition studies among Roma are scarce and to date no quantified dietary data are available. This report provides, for the first time, quantified dietary data and comprehensive anthropometric information for the Hungarian Roma (HR) population, with Hungarian general (HG) adults as reference. Data were obtained from a complex comparative health survey, involving 387 and 410 subjects of HR and HG populations, respectively. Using corporal measurements, body composition indicators were constructed, while daily nutrient intakes were evaluated in comparison with internationally accepted guidelines on nutrient requirements and recommended intakes. Associations between Roma ethnicity and nutrient intakes, as well as odds of achieving dietary recommendations were explored using regression models, adjusted for relevant covariates (i.e., age, gender, education, marital status and perceived financial status). Results showed occasional differences for selected nutrient intakes between the groups, with HR's intake being less favorable. Total fat intake, predominantly animal-sourced, exceeded recommendations among HR (36.1 g, 95% confidence interval (CI): 35.2-37.0) and was not dissimilar to HG group (37.1 g, 95% CI: 36.3-38.0). Sodium intake among HR was significantly lower (5094.4 mg, 95% CI: 4866.0-5322.8) compared to HG (5644.0 mg, 95% CI: 5351.9-5936.0), but significantly greater than recommended intake in both groups. HR had greater estimated body fatness (25.6-35.1%) and higher average body mass index (BMI, 27.7 kg/m², 95% CI: 26.9-28.4), compared to HG. In addition, HR had lower odds of achieving dietary recommendations (odds ratio (OR) = 0.81, 95% CI: 0.67-0.97, p < 0.05). Findings warrant further research, while highlighting the importance of establishing and integrating Roma nutrition into national surveillance and monitoring systems for key dietary risk factors.

Applicability of Obesity-Related SNPs and their Effect Size Measures Defined on Populations with European Ancestry for Genetic Risk Estimation among Roma

Investigations on the impact of genetic factors on the development of obesity have been limited regarding the Roma population—the largest and most vulnerable ethnic minority in Europe of Asian origin. Genetic variants identified from genetic association studies are primarily from European populations. With that in mind, we investigated the applicability of data on selected obesity-related single nucleotide polymorphisms (SNPs), obtained from the Hungarian general (HG) population of European origin, on the Hungarian Roma (HR) population. Twenty preselected SNPs in susceptible alleles, known to be significantly associated with obesity-related phenotypes, were used to estimate the effect of these SNPs on body mass index (BMI) and waist circumference (WC) in HG (N = 1783) and HR (N = 1225) populations. Single SNP associations were tested using linear and logistic regression models, adjusted for known covariates. Out of 20 SNPs, four located in FTO (rs1121980, rs1558902, rs9939609, and rs9941349) showed strong association with BMI and WC as continuous variables in both samples. Computations based on Adult Treatment Panel III (ATPIII) and the International Diabetes Federation’s (IDF) European and Asian criteria showed rs9941349 in FTO to be associated only with WC among both populations, and two SNPs (rs2867125, rs6548238) in TMEM18 associated with WC only in HG population. A substantial difference (both in direction and effect size) was observed only in the case of rs1801282 in PPARγ on WC as a continuous outcome. Findings suggest that genetic risk scores based on counting SNPs with relatively high effect sizes, defined based on populations with European ancestry, can sufficiently allow estimation of genetic susceptibility for Roma. Further studies are needed to clarify the role of SNP(s) with protective effect(s).

Mitochondrial DNA diversity of the Roma from northeastern Bosnia, Bosnia and Herzegovina

This study is the first report on the mtDNA diversity in the Roma population from Bosnia. The main aim of this study was to analyse the mtDNA diversity in the studied population, evaluate the genetic relations with other European Roma populations, and analyse the influences of the Roma gene flow on the mitochondrial profile of the Roma from northeastern Bosnia. MtDNA variability in the analysed population has been studied by means of hypervariable segment I and II (HVSI/II) of the control region sequencing and analysis of restriction fragment-length polymorphisms of the coding region. Our results show that genetic structure of the Roma from northeastern Bosnia has a combination of lineages of three main layers: specific founder of Indian origin (M5a1 and M35b) and founder non-M lineages of Indian/European origin (H7a, X2b and X2d) and lineages of European/Middle East origin (H, H1, H11a, V, T2b, K1b and W). The distribution of the haplogroups in the gene pool of the comparative European Roma populations indicates the separate origin of the Bosnian Roma and the Bulgarian Vlax and Croatian Vlax Roma. The data suggest that mitochondrial gene pool of the Roma population from northeastern Bosnia might be a consequence of early parting and the later different migration routes that are part of their demographic history. Our data confirm the high genetic heterogeneity of the Roma populations that can be shaped by effects of genetic drift, isolation and low effective population size, and this correlates with the migratory history of the Roma.

Revealing the impact of the Caucasus region on the genetic legacy of Romani people from genome-wide data

Romani people are a significant minority in Europe counting about 10 million individuals scattered throughout the continent. They are a migratory group originating from Northwestern India. Their exodus from India occurred approximately 1000–1500 years ago. The migration route of the Romani people was reconstructed with the help of cultural anthropology, linguistics and historical records. Their migration made them through Central Asia, Middle East and the Caucasus region, prior to the arriving into Europe. Yet the significance of these regions, especially of the Caucasus, in Roma ancestry was a rather neglected topic. Contribution of the Caucasus and further affected regions to the ancestry of Roma was investigated based on genome-wide autosomal marker data. 158 European Roma samples and 41 populations from the Caucasus region, from Middle East, Central Asia and from South Asia were considered in our tests. Population structure and ancestry analysis algorithms were applied to investigate the relationship of Roma with these populations. Identical by descent DNA segment analyses and admixture linkage disequilibrium based tests were also applied. Our results suggest that the Caucasus region plays also a significant role in the genetic legacy of Romani people besides the main sources, Europe and South Asia, previously investigated by other population genetic studies. The Middle East and Central Asia seems slightly less important but far from negligible in connection with the sources of Roma ancestry. Our results point out that the Caucasus region and altogether the area of the Caspian and Black Seas had a significant role in the migration of Romani people towards Europe and contributed significantly to the genetic legacy of Roma rival to the European and Indian main sources.

Reproductive Investment and Health Costs in Roma Women

In this paper, we examine whether variation in reproductive investment affects the health of Roma women using a dataset collected through original anthropological fieldwork among Roma women in Serbia. Data were collected in 2014–2016 in several Roma semi-urban settlements in central Serbia. The sample consisted of 468 Roma women, averaging 44 years of age. We collected demographic data (age, school levels, socioeconomic status), risk behaviors (smoking and alcohol consumption), marital status, and reproductive history variables (the timing of reproduction, the intensity of reproduction, reproductive effort and investment after birth), in addition to self-reported health, height, and weight. Data analyses showed that somatic, short-term costs of reproduction were revealed in this population, while evolutionary, long-term costs were unobservable—contrariwise, Roma women in poor health contributed more to the gene pool of the next generation than their healthy counterparts. Our findings appear to be consistent with simple trade-off models that suggest inverse relationships between reproductive effort and health. Thus, personal sacrifice—poor health as an outcome—seems crucial for greater reproductive success.

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.

Electronic supplementary material

The online version of this article (10.1186/s12863-017-0547-x) contains supplementary material, which is available to authorized users.

Prevalence of URAT1 allelic variants in the Roma population

The Roma represents a transnational ethnic group, with a current European population of 8-10 million. The evolutionary process that had the greatest impact on the gene pool of the Roma population is called the founder effect. Renal hypouricemia (RHUC) is a rare heterogenous inherited disorder characterized by impaired renal urate reabsorption. The affected individuals are predisposed to recurrent episodes of exercise-induced nonmyoglobinuric acute kidney injury and nephrolithiasis. To date, more than 150 patients with a loss-of-function mutation for the SLC22A12 (URAT1) gene have been found, most of whom are Asians. However, RHUC 1 patients have been described in a variety of ethnic groups (e.g., Arab Israelis, Iraqi Jews, Caucasians, and Roma) and in geographically noncontiguous countries. This study confirms our previous findings regarding the high frequency of SLC22A12 variants observed. Frequencies of the c.1245_1253del and c.1400C>T variants were found to be 1.92% and 5.56%, respectively, in a subgroup of the Roma population from five regions in three countries: Slovakia, Czech Republic, and Spain. Our findings suggested that the common dysfunction allelic variants of URAT1 exist in the general Roma population and thus renal hypouricemia should be kept in differential diagnostic algorithm on Roma patients with defect in renal tubular urate transport. This leads to confirm that the genetic drift in the Roma have increased the prevalence of hereditary disorders caused by very rare variants in major population.

Health-endangering everyday settings and practices in a rural segregated Roma settlement in Slovakia: A descriptive summary from an exploratory longitudinal case study

Background

Research into social root-causes of poor health within segregated Roma communities in Central and Eastern Europe, i.e. research into how, why and by whom high health-endangering settings and exposures are maintained here, is lacking. The aim of this study was to assess the local setup of health-endangering everyday settings and practices over the long-term in one such community. It is the initial part of a larger longitudinal study qualitatively exploring the social root-causes of poor Roma health status through the case of a particular settlement in Slovakia.

Methods

The study, spanning 10 years, comprised four methodologically distinct phases combining ethnography and applied medical-anthropological surveying. The acquired data consisted of field notes on participant observations and records of elicitations focusing on both the setup and the social root-causes of local everyday health-endangering settings and practices. To create the here-presented descriptive summary of the local setup, we performed a qualitative content analysis based on the latest World Health Organization classification of health exposures.

Results

Across all the examined dimensions – material circumstances, psychosocial factors, health-related behaviours, social cohesion and healthcare utilization – all the settlements’ residents faced a wide range of health-endangering settings and practices. How the residents engaged in some of these exposures and how these exposures affected residents’ health varied according to local social stratifications. Most of the patterns described prevailed over the 10-year period. Some local health-endangering settings and practices were praised by most inhabitants using racialized ethnic terms constructed in contrast or in direct opposition to alleged non-Roma norms and ways.

Conclusions

Our summary provides a comprehensive and conveniently structured basis for grounded thinking about the intermediary social determinants of health within segregated Roma communities in Slovakia and beyond. It offers novel clues regarding how certain determinants might vary therein; how they might be contributing to health-deterioration; and how they might be causally inter-linked here. It also suggests racialized ethnically framed social counter-norms might be involved in the maintenance of analogous exposure setups.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-017-4029-x) contains supplementary material, which is available to authorized users.

Indian signatures in the westernmost edge of the European Romani diaspora: new insight from mitogenomes

In agreement with historical documentation, several genetic studies have revealed ancestral links between the European Romani and India. The entire mitochondrial DNA (mtDNA) of 27 Spanish Romani was sequenced in order to shed further light on the origins of this population. The data were analyzed together with a large published dataset (mainly hypervariable region I [HVS-I] haplotypes) of Romani (N=1,353) and non-Romani worldwide populations (N>150,000). Analysis of mitogenomes allowed the characterization of various Romani-specific clades. M5a1b1a1 is the most distinctive European Romani haplogroup; it is present in all Romani groups at variable frequencies (with only sporadic findings in non-Romani) and represents 18% of their mtDNA pool. Its phylogeographic features indicate that M5a1b1a1 originated 1.5 thousand years ago (kya; 95% CI: 1.3-1.8) in a proto-Romani population living in Northwest India. U3 represents the most characteristic Romani haplogroup of European/Near Eastern origin (12.4%); it appears at dissimilar frequencies across the continent (Iberia: ≈ 31%; Eastern/Central Europe: ≈ 13%). All U3 mitogenomes of our Iberian Romani sample fall within a new sub-clade, U3b1c, which can be dated to 0.5 kya (95% CI: 0.3-0.7); therefore, signaling a lower bound for the founder event that followed admixture in Europe/Near East. Other minor European/Near Eastern haplogroups (e.g. H24, H88a) were also assimilated into the Romani by introgression with neighboring populations during their diaspora into Europe; yet some show a differentiation from the phylogenetically closest non-Romani counterpart. The phylogeny of Romani mitogenomes shows clear signatures of low effective population sizes and founder effects. Overall, these results are in good agreement with historical documentation, suggesting that cultural identity and relative isolation have allowed the Romani to preserve a distinctive mtDNA heritage, with some features linking them unequivocally to their ancestral Indian homeland.

Reconstructing Roma history from genome-wide data

The Roma people, living throughout Europe and West Asia, are a diverse population linked by the Romani language and culture. Previous linguistic and genetic studies have suggested that the Roma migrated into Europe from South Asia about 1,000-1,500 years ago. Genetic inferences about Roma history have mostly focused on the Y chromosome and mitochondrial DNA. To explore what additional information can be learned from genome-wide data, we analyzed data from six Roma groups that we genotyped at hundreds of thousands of single nucleotide polymorphisms (SNPs). We estimate that the Roma harbor about 80% West Eurasian ancestry-derived from a combination of European and South Asian sources-and that the date of admixture of South Asian and European ancestry was about 850 years before present. We provide evidence for Eastern Europe being a major source of European ancestry, and North-west India being a major source of the South Asian ancestry in the Roma. By computing allele sharing as a measure of linkage disequilibrium, we estimate that the migration of Roma out of the Indian subcontinent was accompanied by a severe founder event, which appears to have been followed by a major demographic expansion after the arrival in Europe.

The phylogeography of Y-chromosome haplogroup h1a1a-m82 reveals the likely Indian origin of the European Romani populations

Linguistic and genetic studies on Roma populations inhabited in Europe have unequivocally traced these populations to the Indian subcontinent. However, the exact parental population group and time of the out-of-India dispersal have remained disputed. In the absence of archaeological records and with only scanty historical documentation of the Roma, comparative linguistic studies were the first to identify their Indian origin. Recently, molecular studies on the basis of disease-causing mutations and haploid DNA markers (i.e. mtDNA and Y-chromosome) supported the linguistic view. The presence of Indian-specific Y-chromosome haplogroup H1a1a-M82 and mtDNA haplogroups M5a1, M18 and M35b among Roma has corroborated that their South Asian origins and later admixture with Near Eastern and European populations. However, previous studies have left unanswered questions about the exact parental population groups in South Asia. Here we present a detailed phylogeographical study of Y-chromosomal haplogroup H1a1a-M82 in a data set of more than 10,000 global samples to discern a more precise ancestral source of European Romani populations. The phylogeographical patterns and diversity estimates indicate an early origin of this haplogroup in the Indian subcontinent and its further expansion to other regions. Tellingly, the short tandem repeat (STR) based network of H1a1a-M82 lineages displayed the closest connection of Romani haplotypes with the traditional scheduled caste and scheduled tribe population groups of northwestern India.

Reconstructing the Indian origin and dispersal of the European Roma: a maternal genetic perspective

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.

Hungarian mtDNA population databases from Budapest and the Baranya county Roma

To facilitate forensic mtDNA testing in Hungary, we have generated control region databases for two Hungarian populations: 211 individuals were sampled from the urban Budapest population and 208 individuals were sampled from a Romani ("gypsy") population in Baranya county. Sequences were generated using a highly redundant approach to minimize potential database errors. The Budapest population had high sequence diversity with 180 lineages, 183 polymorphic positions, and a random match probability of 1%. In contrast, the Romani population exhibited low sequence diversity, with only 56 lineages, 109 segregating sites, and a random match probability of 8.8%. The mtDNA haplogroup compositions of the two populations were also distinct, with the large proportion of haplogroup M samples (35%) in the Roma the most obvious difference between the two populations. These factors highlight the importance of considering population structure when generating reference databases for forensic testing purposes. Comparisons between our Romani population sample and other published data indicate the need for heightened caution when sampling and using mtDNA databases of small endogamous populations. The Romani populations that we compared showed significant departures from genetic uniformity.