[Mitochondrial genome and human mitochondrial diseases].

Today there are described more than 400 point mutations and more than hundred of structural rearrangements of mitochondrial DNA associated with characteristic neuromuscular and other mitochondrial syndromes, from lethal in the neonatal period of life to the disease with late onset. The defects of oxidative phosphorylation are the main reasons of mitochondrial disease development. Phenotypic diversity and phenomenon of heteroplasmy are the hallmark of mitochondrial human diseases. It is necessary to assess the amount of mutant mtDNA accurately, since the level of heteroplasmy largely determines the phenotypic manifestation. In spite of better understanding of the processes of phenotypic expression, currently there are no adequate treatments for mitochondrial diseases.

[Role of natural selection in evolution of mitochondrial haplogroups from Northeastern Eurasia].

The role of natural selection in the evolution of human populations from Northeastern Eurasia was studied. Selection for the regions-specific haplogroup C was demonstrated.

[The genetic history of long-term Russian resident populations of polar northeastern Siberia based on mitochondrial DNA variability].

The mtDNA variation has been studied in representatives of the Russkoe Ust'e (n = 30), Kolyma (n = 31), and Markovo (n = 26) ethnic subgroups originating from Russian military men, hunters, and fishers who married local Yukaghir women and settled at the Arctic Ocean coast and on the Anadyr' River more than 350 years ago. The mtDNA haplotypes characteristic of indigenous Siberian peoples have been demonstrated to form the basis of the mitochondrial gene pool of long-term Russian resident populations of the region. Only one of 30 identified haplotypes belonging to 11 haplogroups (H2a) is characteristic of European populations. The C and D haplogroups are the most diverse. The analysis has revealed the characteristics of the population structure of the long-term Russian resident populations and allowed them to be interpreted in terms of recent historical and environmental processes.

[Analysis of the mitochondrial DNA diversity in Yukaghirs in the evolutionary context].

Based on the mtDNA first hypervariable segment sequence variation data, statistical analysis of the diversity in Yukaghirs in comparison with the other indigenous populations of Siberia, was carried out. The level of the Yukaghir mtDNA gene diversity (GD) constituted 0.920, which was only slightly different from the corresponding estimate for the other Siberian populations. Integral estimates of the genetic structure of Siberian populations (k, S, theta(s), and pi) are presented. Phylogenetic analysis, performed using the neighbor-joining method, showed that the Siberian populations clustered irrespectively to their language affiliation. Negative F(s) values found in Yukaghirs pointed to the possible influence of adaptive selection.

[Spectrum of pathogenic mtDNA mutations in Leber hereditary optic neuropathy families from Siberia].

The results of clinical, genealogical and molecular investigation of eighteen families with Leber hereditary optic neuropathy (LHON), identified on the territory of Siberia during the period from 1997 to 2005, are presented. Comprehensive analysis of mitochondrial genome variations in probands and their matrilineal relatives revealed the presence of relatively frequent (G11778A, G3460A, and T14484C), as well as rare and new mutations with the established or presumptive pathological effect (T10663C, G363A, C4640T, and A14619G). The G11778A mutation was detected in nine pedigrees (50%), mostly in the families of ethnic Russians. In eight of these families G11778A was found in preferred association with the coding-region substitutions, typical of western Eurasian mtDNA lineage (haplogroup) TJ. On the contrary, the G3460A mutation was detected in the three families belonging to the indigenous Siberian populations (Tuvinians, Altaians, and Buryats). It was associated with clearly different haplotypes of eastern Eurasian haplogroups, C3, D5, and D8. Unexpectedly, the G3460A de novo mutation was found in a large Tuvinian pedigree. At the same time, in eleven out of fourteen families of Caucasoid origin pathogenic mutations in the ND genes were associated with the T4216C and C1542A coding-region mutations, marking the root motif of haplogoup TJ. It is suggested that phylogenetically ancient mutations could have provided their carriers with the adaptive advantages upon the development of Central and Northern Europe at the end of the last glaciation (10 000 to 9 000 years ago), thereby, contributing to the preservation of weekly pathogenic LHON mutations, appearing at specific genetic background.

Variation of HLA class II genes in the Nganasan and Ket, two aboriginal Siberian populations.

Allelic frequencies at the three most polymorphic loci of the HLA class II region (DRB1, DQA1 and DQB1) were determined in the Nganasan and Ket, the remnants of the two most ancient groups in the Lower Yenisey River/Taimyr Peninsula region in northern Siberia. By single-stranded conformational polymorphism typing, verified by sequencing, 19 HLA-DRB1-DQA1-DQB1 haplotypes and 15 HLA-DRB1, seven DQA1 and 11 DQB1 alleles were found. The most frequent alleles were DRB1*1301 (23.5%), DQA1*0103 (29.4%), *0501/03/05 (29.4%), and DQB1*0301/09 (32.4%) in the Ket, and DRB1*0901 (25%), DQA1*0301 (39.6%), and DQB1*0301/09 (37.5%) in the Nganasan. The distribution patterns and comprehensive phylogenic analysis based on the haplotype frequencies of 17 Siberian populations suggest that the founders of both the Ket and the Nganasan came from Palaeolithic populations in the Altai-Sayan Upland.

[Genetic history of Aleuts of the Komandor islands from results of analyzing variability of class II HLA genes]. / Geneticheskaia istoriia aleutov komandorskikh ostrovov po rezul'tatam analiza izmenchivosti HLA-genov II klassa.

Variability of the HLA class II genes (alleles of the DRB1, DQA1, and DQB1 loci) was investigated in a sample of Aleuts of the Commanders (n = 31), whose ancestors inhabited the Commander Islands for many thousand years. Among 19 haplotypes revealed in Aleuts of the Commanders, at most eight were inherited from the native inhabitants of the Commander Islands. Five of these haplotypes (DRB1*0401-DQA1*0301-DQB1*0301, DRB1*1401-DQA1*0101-DQB1*0503, DRB1*0802-DQA1*0401-DQB1*0402, DRB1*1101-DQA1*0501-DQB1*0301, and DRB1*1201-DQA1*0501-DQB1*0301) were typical of Beringian Mongoloids, i.e., Coastal Chukchi and Koryaks, as well as Siberian and Alaskan Eskimos. Genetic contribution of the immigrants to the genetic pool of proper Aleuts constituted about 52%. Phylogenetic analysis based on Transberingian distribution of the DRB1 allele frequencies favored the hypothesis on the common origin of Paleo-Aleuts, Paleo-Eskimos, and the Indians from the northwestern North America, whose direct ancestors survived in Beringian/southwestern Alaskan coastal refugia during the late Ice Age.

[Mitochondrial DNA variation in Kets and Nganasans and the early peoples of Northern Eurasia]. / Izmenchivost' mitokhondrial'noi DNK u ketov i nganasan v sviazi s pervonachal'nym zaseleniem Severnoi Evrazii.

Mitochondrial DNA (mtDNA) variation was studied in 38 Kets and 24 Nganasans, the indigenous inhabitants of the north of the Yenisey River Basin and the Taimyr Peninsula. The results were compared with the analogous data obtained for 59 Kondinski and 39 Sos'vinski Mansi. As a whole, mitochondrial gene pool of Mansi, Nganasans, and Kets was characterized by unique combination of European-specific (H, H2, H3, H8, U2, U4, U5, U7, J2, and W) and Asian-specific (A, C, D, and Z) mtDNA haplogroups. Specific features of the haplogroup geographical distribution along with the results of phylogenetic reconstruction favor the hypothesis of the genetic trace left in Eastern Cis-Urals and the adjacent Siberian territories by early migrations from the Near East.

[The mitochondrial genome and human mitochondrial diseases]. / Mitokhondrial'nyi genom i mitokhondrial'nye bolezni cheloveka.

To date, more than 100 point mutations and several hundreds of structural rearrangements of mitochondrial DNA (mtDNA) are known too be connected with characteristic neuromuscular and other mitochondrial syndromes varying form those causing death at the neonatal stage to diseases with late ages of onset. The immediate cause of mitochondrial disorders is a defective oxidative phosphorylation. Wide phenotypic variation and the heteroplasmy phenomenon, which some authors include in mutation load, are characteristic of human mitochondrial diseases. As the numbers of cases identified and pedigrees described increase, data on the genotype--phenotype interaction and the structure and frequency of pathogenic and conditionally pathogenic mtDNA mutations in human populations are rapidly accumulated. The data on the genetics and epidemiology of mitochondrial diseases are not only important for differential diagnosis and genetic counseling. Since both neutral and mildly pathogenic mutations of mtDNA are progressively accumulated in maternal phyletic lines, molecular analysis of these mutations permits not only reconstruction of the genealogical tree of modern humans, but also estimation of the role that these mutations play in natural selection.

Novel mtDNA mutations and oxidative phosphorylation dysfunction in Russian LHON families.

Leber's hereditary optic neuropathy (LHON) is characterized by maternally transmitted, bilateral, central vision loss in young adults. It is caused by mutations in the mitochondrial DNA (mtDNA) encoded genes that contribute polypeptides to NADH dehydrogenase or complex I. Four mtDNA variants, the nucleotide pair (np) 3460A, 11778A, 14484C, and 14459A mutations, are known as "primary" LHON mutations and are found in most, but not all, of the LHON families reported to date. Here, we report the extensive genetic and biochemical analysis of five Russian families from the Novosibirsk region of Siberia manifesting maternally transmitted optic atrophy consistent with LHON. Three of the five families harbor known LHON primary mutations. Complete sequence analysis of proband mtDNA in the other two families has revealed novel complex I mutations at nps 3635A and 4640C, respectively. These mutations are homoplasmic and have not been reported in the literature. Biochemical analysis of complex I in patient lymphoblasts and transmitochondrial cybrids demonstrated a respiration defect with complex-I-linked substrates, although the specific activity of complex I was not reduced. Overall, our data suggests that the spectrum of mtDNA mutations associated with LHON in Russia is similar to that in Europe and North America and that the np 3635A and 4640C mutations may be additional mtDNA complex I mutations contributing to LHON expression.

Mitochondrial DNA variation in Koryaks and Itel'men: population replacement in the Okhotsk Sea-Bering Sea region during the Neolithic.

In this study, we analyzed the mitochondrial DNA (mtDNA) variation in 202 individuals representing one Itel'men and three Koryak populations from different parts of the Kamchatka peninsula. All mtDNAs were subjected to high resolution restriction (RFLP) analysis and control region (CR) sequencing, and the resulting data were combined with those available for other Siberian and east Asian populations and subjected to statistical and phylogenetic analysis. Together, the Koryaks and Itel'men were found to have mtDNAs belonging to three (A, C, and D) of the four major haplotype groups (haplogroups) observed in Siberian and Native American populations (A-D). In addition, they exhibited mtDNAs belonging to haplogroups G, Y, and Z, which were formerly called "Other" mtDNAs. While Kamchatka harbored the highest frequencies of haplogroup G mtDNAs, which were widely distributed in eastern Siberian and adjacent east Asian populations, the distribution of haplogroup Y was restricted within a relatively small area and pointed to the lower Amur River-Sakhalin Island region as its place of origin. In contrast, the pattern of distribution and the origin of haplogroup Z mtDNAs remained unclear. Furthermore, phylogenetic and statistical analyses showed that Koryaks and Itel'men had stronger genetic affinities with eastern Siberian/east Asian populations than to those of the north Pacific Rim. These results were consistent with colonization events associated with the relatively recent immigration to Kamchatka of new tribes from the Siberian mainland region, although remnants of ancient Beringian populations were still evident in the Koryak and Itel'men gene pools.

mtDNA diversity in Chukchi and Siberian Eskimos: implications for the genetic history of Ancient Beringia and the peopling of the New World.

The mtDNAs of 145 individuals representing the aboriginal populations of Chukotka-the Chukchi and Siberian Eskimos-were subjected to RFLP analysis and control-region sequencing. This analysis showed that the core of the genetic makeup of the Chukchi and Siberian Eskimos consisted of three (A, C, and D) of the four primary mtDNA haplotype groups (haplogroups) (A-D) observed in Native Americans, with haplogroup A being the most prevalent in both Chukotkan populations. Two unique haplotypes belonging to haplogroup G (formerly called "other" mtDNAs) were also observed in a few Chukchi, and these have apparently been acquired through gene flow from adjacent Kamchatka, where haplogroup G is prevalent in the Koryak and Itel'men. In addition, a 16111C-->T transition appears to delineate an "American" enclave of haplogroup A mtDNAs in northeastern Siberia, whereas the 16192C-->T transition demarcates a "northern Pacific Rim" cluster within this haplogroup. Furthermore, the sequence-divergence estimates for haplogroups A, C, and D of Siberian and Native American populations indicate that the earliest inhabitants of Beringia possessed a limited number of founding mtDNA haplotypes and that the first humans expanded into the New World approximately 34,000 years before present (YBP). Subsequent migration 16,000-13,000 YBP apparently brought a restricted number of haplogroup B haplotypes to the Americas. For millennia, Beringia may have been the repository of the respective founding sequences that selectively penetrated into northern North America from western Alaska.

Polymorphism of the HLA class II loci in Siberian populations.

The populations that colonized Siberia diverged from one another in the Paleolithic and evolved in isolation until today. These populations are therefore a rich source of information about the conditions under which the initial divergence of modern humans occurred. In the present study we used the HLA system, first, to investigate the evolution of the human major histocompatibility complex (MHC) itself, and second, to reveal the relationships among Siberian populations. We determined allelic frequencies at five HLA class II loci (DRB1, DQA1, DQB1, DPA1, and DPB1) in seven Siberian populations (Ket, Evenk, Koryak, Chukchi, Nivkh, Udege, and Siberian Eskimo) by the combination of single-stranded conformational polymorphism and DNA sequencing analysis. We then used the gene frequency data to deduce the HLA class II haplotypes and their frequencies. Despite high polymorphism at four of the five loci, no new alleles could be detected. This finding is consistent with a conserved evolution of human class II MHC genes. We found a high number of HLA class II haplotypes in Siberian populations. More haplotypes have been found in Siberia than in any other population. Some of the haplotypes are shared with non-Siberian populations, but most of them are new, and some represent "forbidden" combinations of DQA1 and DQB1 alleles. We suggest that a set of "public" haplotypes was brought to Siberia with the colonizers but that most of the new haplotypes were generated in Siberia by recombination and are part of a haplotype pool that is turning over rapidly. The allelic frequencies at the DRB1 locus divide the Siberian populations into eastern and central Siberian branches; only the former shows a clear genealogical relationship to Amerinds.

Y chromosome polymorphisms in native American and Siberian populations: identification of native American Y chromosome haplotypes.

We have initiated a study of ancient male migrations from Siberia to the Americas using Y chromosome polymorphisms. The first polymorphism examined, a C-->T transition at nucleotide position 181 of the DYS199 locus, was previously reported only in Native American populations. To investigate the origin of this DYS199 polymorphism, we screened Y chromosomes from a number of Siberian, Asian, and Native American populations for this and other markers. This survey detected the T allele in all five Native American populations studied at an average frequency of 61%, and in two of nine native Siberian populations, the Siberian Eskimo (21%) and the Chukchi (17%). This finding suggested that the DYS199 T allele may have originated in Beringia and was then spread throughout the New World by the founding populations of the major subgroups of modern Native Americans. We further characterized Native American Y chromosome variation by analyzing two additional Y chromosome polymorphisms, the DYS287 Y Alu polymorphic (YAP) element insertion and a YAP-associated A-->G transition at DYS271, both commonly found in Africans. We found neither African allele associated with the DYS199 T allele in any of the Native American or native Siberian populations. However, we did find DYS287 YAP+ individuals who harbored the DYS199 C allele in one Native American population, the Mixe, and in one Asian group, the Tibetans. A correlation of these Y chromosome alleles in Native Americans with those of the DYS1 locus, as detected by the p49a/p49f (p49a,f) probes on TaqI-digested genomic DNA, revealed a complete association of DYS1 alleles (p49a,f haplotypes) 13, 18, 66, 67 and 69 with the DYS199 T allele, while DYS1 alleles 8 and 63 were associated with both the DYS199 C and T allele.

[Mitochondrial DNA variation in native inhabitants of Siberia with reconstructions of the evolutional history of the American Indians. Restriction polymorphism]. / Izmenchivost' mitokhondrial'nykh DNK u korennykh zhitelei Sibiri v sviazi s rekonstruktsiei évoliutsionnoi istorii amerikanskikh indeitsev.

Restriction polymorphism of mitochondrial DNA (mtDNA) isolated from the blood of 107 Koryaks, 28 Northern Altaians, and 23 Kets was studied. The results were compared with similar data that in aggregate characterized haplotypes of 569 individual DNAs from 13 Siberian populations, in order to elucidate the genetic similarity and differences between mtDNA haplogroups of native Siberians and Americans. Natives of Siberia are distinguished by the significant variation of the composition and frequency of three (A, C, and D) of four haplogroups characteristic of American Indians. In the full composition, all four haplogroups-A, B, C, and D-are found only in a sample of Northern Altaians. The peculiarities of their geographical distribution in Asia allow us to consider the southern regions of Siberia and the adjacent territories of Central and East Asia as the site inhabited by the ancestors of the first wave of migrants to North America.

VNTR DNA variation in Siberian indigenous populations.

The VNTR loci D7S104, D11S129, D18S17, D20S15, and D21S112 in three indigenous Siberian populations were analyzed to determine the populations' genetic structure. Using the Kolmogorov-Smirnov test, we found that the Siberian indigenous populations of Surinda and Sulamai are separated at the D11S129 locus (p < 0.05). However, the population of Poligus is genetically homogeneous compared with the villages of Sulamai and Surinda. Principal component plots for the sets of VNTR loci cluster the Siberian groups together, reflecting the homogeneity of these populations. An analysis of mean per locus heterozygosity versus the distance from the centroid of distribution suggests gene flow into Sulamai but little genetic exchange with Surinda and Poligus. Ultimately, the VNTR data reflect the genetic distinctiveness of the Kets and the Evenki.

Virologic and genetic studies relate Amerind origins to the indigenous people of the Mongolia/Manchuria/southeastern Siberia region.

A commonly held theory is that the first wave of migrants into the New World was derivative from the ethnic groups then inhibiting eastern Siberia. However, these ethnic groups lack a mtDNA haplogroup (B) that is well represented in Amerindian tribes. Also, the time depth of the other three mtDNA haplogroups found in Amerindians (A, C, and D) appears to be greater in the Amerindians than in the eastern Siberian ethnic groups. In this communication we demonstrate that the human T-cell lymphotrophic virus type II, present in 11 of the 38 Amerindian tribes thus far examined, is not present in any of the 10 ethnic groups of eastern Siberia that we have studied. However, the virus has just been reported in the indigenous population of Mongolia, and mtDNA haplogroup B is also represented in this region. On the basis of these facts, we propose that the ancestors of the first migrants to the New World were not derived from north and central Siberia but from populations to the south, inhabiting the regions of Mongolia, Manchuria, and/or the extreme southeastern tip of Siberia.

Predicted maximal oxygen consumption of indigenous Siberians.

This study presents physical fitness data on two indigenous Siberian populations, the Evenki and Keto. The Canadian Aerobic Test of Fitness (CATF) was utilized to provide estimates of maximal oxygen consumption (V̇O2 max) for a sample of 44 subjects (30 males, 14 females) as baseline data for further studies on changing fitness levels and the health problems associated with acculturation. Estimates of V̇O2 max average 46.2 ml kg-1 min-1 for males and 33.9 ml kg-1 min-1 for females. These values are comparable to those previously reported for other semisubsistence, cold adapted populations. The Siberian groups are below the Canadian norms in the 15-19 year age range, and thereafter track at about the 50th percentile throughout adulthood. This suggests that the cardiorespiratory systems of adult Evenki and Keto are functionally comparable to the average adult Canadian. © 1994 Wiley-Liss, Inc.

mtDNA variation of aboriginal Siberians reveals distinct genetic affinities with Native Americans.

The mtDNA variation of 411 individuals from 10 aboriginal Siberian populations was analyzed in an effort to delineate the relationships between Siberian and Native American populations. All mtDNAs were characterized by PCR amplification and restriction analysis, and a subset of them was characterized by control region sequencing. The resulting data were then compiled with previous mtDNA data from Native Americans and Asians and were used for phylogenetic analyses and sequence divergence estimations. Aboriginal Siberian populations exhibited mtDNAs from three (A, C, and D) of the four haplogroups observed in Native Americans. However, none of the Siberian populations showed mtDNAs from the fourth haplogroup, group B. The presence of group B deletion haplotypes in East Asian and Native American populations but their absence in Siberians raises the possibility that haplogroup B could represent a migratory event distinct from the one(s) which brought group A, C, and D mtDNAs to the Americas. Our findings support the hypothesis that the first humans to move from Siberia to the Americas carried with them a limited number of founding mtDNAs and that the initial migration occurred between 17,000-34,000 years before present.