Identification in Portugal and Brazil of a mtDNA lineage containing a 9-bptriplication of the intergenic COII/tRNA(Lys) region

Although the deletion of one of the 9-bp repeats in region V of mitochondri al DNA is very common in Asians, Asian-derived populations and Africans, th e triplication of the 9-bp segment was described only a few times, mostly o n individuals from Asian origin. Here, we report for the first time the pre sence of the 9-bp triplication in Europeans. The triplication was initially found in one Brazilian individual. Sequencing of the hypervariable segment s I (HVS1) and II (HVS2) of the control region and RFLP analysis of the cod ing region classified the mtDNA as belonging to the European haplogroup H. Since white Brazilians are predominantly of Portuguese descent, we screened 96 unrelated Northern Portuguese for the 9-bp triplication and found its p resence in two of them (2.1 %), One of these had an mtDNA haplotype identic al to that of the Brazilian individual, while the other differed in a singl e base change in HVS2, The fact that the 9-bp triplication has reached poly morphic frequencies in Northern Portugal and that it has apparently differe ntiated into at least two lineages defined by the mutation in HVS2 suggests that it probably occured a long time ago.