Biomedical subjects

V Spitsyn

Publications and source records attributed to V Spitsyn.

4 recordsLinked to original sources

PubMed1999

Mitochondrial DNA sequence diversity in Russians.

The article presents the results of the first regular study of Russian populations by sequencing the control region of mitochondrial DNA (mtDNA). The sequenced region is the most variable on mtDNA molecule and is commonly used for population and evolutionary studies. Russians form one of the largest ethnic groups (more than 129 million). However, their genetic diversity had only been characterized with RFLP and biochemical markers, although there are already established mtDNA sequence databases for many ethnic groups of the world. We have obtained sequence data from 103 individuals living in three Russian regions: Kostroma, Kursk, and Rjazan. The sequenced fragment analyzed is 360 bp in length (positions from 16024 to 16383). Fifty nine nucleotide positions have been found polymorphic in Russians, among those were 57 transitions and two transversions. One individual is found having two insertions of two cytosines between positions 16184 and 16193. Among 64 different mitotypes identified in the study 52 were unique in these samples. The index of genetic diversity (Nei, 1987) for Russians is 0.96. This value is within the established range for European populations (0.93 to 0.98). Genetic distances calculated from our data show that Russians form a cluster with Germans, Bulgarians, Swedes, Estonians, and Volgo-Finns are more distant from Karelians and Finns, and much more differ from Turks and especially Mongolians.

Base Sequence↗

PubMed1998

The deltaccr5 mutation conferring protection against HIV-1 in Caucasian populations has a single and recent origin in Northeastern Europe.

The chemokine receptor CCR5 is encoded by the CMKBR5 gene located on the p21.3 region of human chromosome 3, and constitutes the major co-receptor for the macrophage-tropic strains of HIV-1. A mutant allele of the CCR5 gene, Delta ccr5 , was shown to provide to homozygotes with a strong resistance against infection by HIV. The frequency of the Delta ccr5 allele was investigated in 18 European populations. A North to South gradient was found, with the highest allele frequencies in Finnish and Mordvinian populations (16%), and the lowest in Sardinia (4%). Highly polymorphic microsatellites (IRI3.1, D3S4579 and IRI3.2, D3S4580 ) located respectively 11 kb upstream and 68 kb downstream of the CCR5 gene deletion were used to determine the haplotype of the chromosomes carrying the Delta ccr5 variant. A strong linkage disequilibrium was found between Delta ccr5 and specific alleles of the IRI3.1 and IRI3.2 microsatellites: >95% of the Delta ccr5 chromosomes carried the IRI3.1-0 allele, while 88% carried the IRI3.2-0 allele. These alleles were found respectively in only 2 or 1.5% of the chromosomes carrying a wild-type CCR5 gene. From these data, it was inferred that most, if not all Delta ccr5 alleles originate from a single mutation event, and that this mutation event probably took place a few thousand years ago in Northeastern Europe. The high frequency of the Delta ccr5 allele in Caucasian populations cannot be explained easily by random genetic drift, suggesting that a selection advantage is or has been associated with homo- or heterozygous carriers of the Delta ccr5 allele.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

The codon 31 polymorphism of the p53-inducible gene p21 shows distinct differences between major ethnic groups.

The codon 31 polymorphism of the p53-inducible protein p21 was studied with respect to allele frequency variations between some major ethnic groups. The frequency of the Al (Arg) allele showed highly significant variations ranging from 4% in Caucasians (Swedes) to 50% in Chinese. Compared to Caucasians, a relatively high frequency was found in African Blacks (29%) and Indians (16%). Furthermore, Finns and Mordvinians also had higher frequencies (9-10%) than west Europeans (French and Swedes), consistent with an Asiatic Mongoloid influence known to exist in Finno-Ugrian tribes. The geographic allele frequency patterns of p53 and its effector protein p21 were quite different. The p21 A1 mutations in African, Asiatic and European populations were identical at the DNA level. The geographical distribution of the A1 allele suggests an independent origin in Africa and Asia. The very pronounced ethnic differentiation of tumour suppressor genes and the fact that tumour suppressor genes may be teratogenes suggest that these polymorphisms are maintained by natural selection, probably operating in the intrauterine period.

Alleles↗

PubMedDate not supplied

Ethnic differences in the HFE codon 282 (Cys/Tyr) polymorphism.

Recent studies have shown that hereditary hemochromatosis (HH) is likely to be caused by homozygosity for a Cys282Tyr mutation in the HFE gene located 4.5 Mb telomeric to HLA-A. Population studies of this polymorphism are facilitated by the fact that the Cys282Tyr mutation creates a Rsal restriction site. We have studied the codon 282 (Cys/Tyr) polymorphism in different ethnic groups. In agreement with previous observations the Tyr allele appeared to be rare or absent in Asiatic (Indian, Chinese) populations. The highest allele frequency (7.5%) was found in Swedes. Saamis (2%) and Mordvinians (1.8%) had significantly lower frequencies of the Tyr allele. Comparisons with allele frequencies based on prevalence estimates of HH showed some disagreements with the RFLP data, particularly in Finns. The newly described HFE marker provides a new approach to the screening of HH as well as studies of the relationship between the HFE Tyr allele and different disorders including cancer.

Alleles↗