Autosomal, mitochondrial, and Y chromosome DNA variation in Finland: Evidence for a male-specific bottleneck

The high prevalence of rare genetic diseases in Finland has been attributed to a founder effect some 2,000 years ago. However, this hypothesis has not been supported from mtDNA sequence and autosomal microsatellite data which indicate high levels of gene diversity. Here we have identified genetic ev idence for a population bottleneck by examining variable microsatellite loc i on the nonrecombining portion of Y chromosomes from Finland and four popu lations from Europe and the Americas. Sequence data from segment I of the c ontrol region (HVS-1) of mtDNA (360 bases) and 20 autosomal dinucleotide re peat markers were also analyzed. Partitions of genetic variance within and between populations revealed significant levels of Y-chromosome differentia tion between populations. Phylogenetic and diversity analyses revealed dive rgent Finnish Y-haplotype clades and significantly lower Y-haplotype divers ity among Finns as compared to other populations. Surprisingly, Finnish Y-h aplotype diversity was even lower than the Native American populations, The se results provide support for the Finnish bottleneck hypothesis. Evidence for two separate founding Finnish Y-chromosome lineages was also observed f rom the Y-chromosome phylogeny, A limited number of closely related foundin g males may have contributed to the low number of paternal lineages in the Finnish population. In contrast, high levels of genetic diversity for mtDNA and autosomal STRs may be the result of sex-biased gene flow and recent im migration to urban areas from established internal isolates within Finland. Published 1999 Wiley-Liss, Inc.