Echoes from Sepharad: signatures on the maternal gene pool of crypto-Jewish descendants

The majority of genetic studies on Jewish populations have been focused on Ashkenazim, and genetic data from the Sephardic original source, the Iberian Peninsula, are particularly scarce. Regarding the mitochondrial genome, the available information is limited to a single Portuguese village, Belmonte, where just two different lineages (a single one corresponding to 93.3%) were found in 30 individuals. Aiming at disclosing the ancestral maternal background of the Portuguese Jewry, we enlarged the sampling to other crypto-Jewish descendants in the Braganca district (NE Portugal). Fifty-seven complete mtDNA genomes were newly sequenced and — in contrast with Belmonte — a high level of diversity was found, with five haplogroups (HV0b, N1, T2b11, T2e and U2e) being putatively identified as Sephardic founding lineages. Therefore — in sharp contrast with Belmonte — these communities have managed to escape the expected inbreeding effects caused by centuries of religious repression and have kept a significant proportion of the Sephardic founder gene pool. This deeper analysis of the surviving Sephardic maternal lineages allowed a much more comprehensive and detailed perspective on the origins and survival of the Sephardic genetic heritage. In line with previously published results on Sephardic paternal lineages, our findings also show a surprising resistance to the erosion of genetic diversity in the maternal lineages.