title: Low variability of the POLG (CAG)n repeat in north Eurasian populations.
abstract: We investigated the frequency of different repeat-length alleles of the trinucleotide CAG microsatellite repeat in the coding sequence of the nuclear gene for the catalytic subunit of mitochondrial DNA polymerase gamma (POLG) in 12 ethnic groups from northern Eurasia. The population sample consisted of 1,330 individuals from 3 large geographic areas: Europe, Southwest Asia, and Siberia/East Asia. We found that the 10-repeat allele of the POLG gene is the most frequent in all analyzed populations, with a frequency of 88-96%. The heterozygosity level ranges from 22% in Europe to 13.6% in Southwest Asia with the lowest value of 7.4% in Siberia/East Asia. The present study provides evidence of clinal distribution of POLG gene heterozygosity in North Eurasian populations. In general, we found an extremely low variability of the trinucleotide CAG microsatellite repeat, suggesting that purifying selection acts against deleterious alleles, although low mutability of the repeated region cannot be ruled out.
authors.affiliation: Institute of Biological Problems of the North, Far-East Branch of the Russian Academy of Sciences, Magadan 685000, Russia.
authors.forename: Boris A
authors.initials: BA
authors.lastname: Malyarchuk
authors.forename: Marta
authors.initials: M
authors.lastname: Papuga
authors.forename: Tomasz
authors.initials: T
authors.lastname: Grzybowski
authors.forename: Igor B
authors.initials: IB
authors.lastname: Rogozin
authors.forename: Marcin
authors.initials: M
authors.lastname: Wozniak
authors.forename: Miroslava V
authors.initials: MV
authors.lastname: Derenko
authors.forename: Serge Yu
authors.initials: SY
authors.lastname: Rychkov
authors.forename: Jakub
authors.initials: J
authors.lastname: Czarny
authors.forename: Ilia A
authors.initials: IA
authors.lastname: Zakharov
authors.forename: Danuta
authors.initials: D
authors.lastname: Miścicka-Sliwka
mesh_terms: D000483:Alleles; D001208:Asia; D000074002:DNA Polymerase gamma; D004272:DNA, Mitochondrial; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D005060:Europe; D014644:Genetic Variation; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D018895:Microsatellite Repeats / Q000235:genetics; D020080:Tandem Repeat Sequences
chemical_list: D004272:DNA, Mitochondrial; D000074002:DNA Polymerase gamma; D004259:DNA-Directed DNA Polymerase; C413027:POLG protein, human