Reconstructing Roma history from genome-wide data

TL;DR

This study uses genome-wide data from six Roma groups to trace their ancestry, migration history, and demographic events, revealing significant admixture and expansion patterns in their European history.

Contribution

It provides a comprehensive genome-wide analysis of Roma ancestry, migration timing, and demographic history, expanding beyond previous Y chromosome and mitochondrial DNA studies.

Findings

Roma have about 80% West Eurasian ancestry from European and South Asian sources.

Admixture between South Asian and European ancestors occurred approximately 850 years ago.

Migration involved a severe founder event followed by demographic expansion in Europe.

Abstract

The Roma people, living throughout Europe, 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 1000-1500 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-deriving 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 ago. 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 we hypothesize was followed by a major demographic expansion once the population arrived in Europe.