CLASSIFICATION OF EUROPEAN MTDNAS FROM AN ANALYSIS 3 EUROPEAN POPULATIONS

Mitochondrial DNA (mtDNA) sequence variation was examined in Finns, Sw edes and Tuscans by PCR amplification and restriction analysis. About 99% of the mtDNAs were subsumed within 10 mtDNA haplogroups (H, I, J, K, M, T, U, V, W, and X) suggesting that the identified haplogroups co uld encompass virtually all European mtDNAs. Because both hypervariabl e segments of the mtDNA control region were previously sequenced in th e Tuscan samples, the mtDNA haplogroups and control region sequences c ould be compared. Using a combination of haplogroup-specific restricti on site changes and control region nucleotide substitutions, the distr ibution of the haplogroups was surveyed through the published restrict ion site polymorphism and control region sequence data of Caucasoids. This supported the conclusion that most haplogroups observed in Europe are Caucasoid-specific, and that at least some of them occur at varyi ng frequencies in different Caucasoid populations. The classification of almost all European mtDNA variation in a number of well defined hap logroups could provide additional insights about the origin and relati onships of Caucasoid populations and the process of human colonization of Europe, and is valuable for the definition of the role played by m tDNA backgrounds in the expression of pathological mtDNA mutations.