PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “HLA polymorphism”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed1983

Epstein-Barr virus-specific cytotoxic T lymphocytes as probes of HLA polymorphism. Heterogeneity of T cell-restricting determinants associated with the serologically defined HLA-A2 antigen.

Epstein-Barr (EB) virus-specific effector T cell lines were established from nine virus-immune donors positive for the serologically defined HLA-A2 antigen; of these, four lines contained a demonstrable A2-restricted cytotoxic component. When these four effector populations were each tested on the same panel of EB virus-transformed lines from 20 HLA-A2-positive individuals, 16 of the target cell lines were consistently killed at levels above 25% of the relevant autologous cell lysis. Cytotoxicity appeared to be mediated through a restricting determinant associated with the 'common A2' antigen that these lines shared; indeed the lysis could be specifically blocked by high concentrations of an HLA-A2-specific monoclonal antibody. In contrast, 4 out of 20 target cell lines were not killed by HLA-A2-restricted effector cells, even though they did express the serologically defined A2 antigen and were found in other tests to be susceptible to EB virus-specific cytolysis restricted through other HLA-A or -B antigens on their surface. These results suggest that EB virus-specific cytotoxic T cells can distinguish between serologically identical HLA-A2 molecules via the heterogeneity of their T cell-restricting determinants. Data from one of the effector cell populations further suggested that a serologically defined cross-reaction between the otherwise distinct HLA-A2 and -Bw57 antigens might also be reflected in a cross-reactivity of T cell-restricting determinants.

Adult↗
PubMed1988

The chromosome region containing the highly polymorphic HLA class I genes displays limited large scale variability in the human population.

The large-scale organization and polymorphism of the HLA class I region was investigated by pulsed field gel (PFG) fractionation of DNA from various HLA-typed cell lines cleaved by different 'rare cutter' restriction enzymes, followed by hybridization with 'general' and locus-specific HLA probes. Results indicate that (i) most HLA class I sequences are contained in a 340 kb MluI DNA fragment which also carries the HLA-A gene; (ii) HLA-A, -B and -C genes are present on different fragments bounded by 'HTF islands' (CpG-rich, unmethylated DNA regions containing multiple sites for 'rare cutter' enzymes) which generally coincide with the 5' regions of expressed genes; and (iii) very little fragment size polymorphism is seen, implying that expansion/contraction events in the HLA class I region due to unequal crossing over (as documented in the mouse class I system) are infrequently found in the human population.

Chromosome Mapping↗
PubMed1978

HLA polymorphism in Israel. 2. Israeli Jews originating from Russia.

HLA typing of 123 Israel Jews of Russian origin showed a high frequency for HLA--A1, A2, Aw19 and B14, Bw16 and Bw35 of the A and B loci, respectively. The most frequently occuring haplotypes were (A1, B17), (Aw25, B18), (Aw26, Bw16), (Aw19, B13), (Aw23, B5) and (Aw25, Bw35). This study reveals a striking resemblance in the distribution of frequencies of HLA alleles and haplotypes between Russian Jews and two other East European Jewish communities (presented in this issue) of Polish and Rumanian origin.

Gene Frequency↗
PubMed2002

HLA polymorphism in six ethnic groups from Pakistan.

The extreme polymorphism found at some of the loci of the HLA system has made it an invaluable tool for population genetic analyses. In this study the genetic polymorphism of six Pakistani ethnic groups was investigated at the HLA-A, -B, -C, -DRB and DQB1 loci using polymerase chain reaction with sequence specific primers. The groups included in this study are the Baloch, Brahui and Sindhi from the south and the Burusho, Kalash and Pathan from the north of Pakistan. The allele frequencies, three-locus haplotype frequencies for HLA-A, -C, -B and HLA-A, -B, -DRB1 are given. Variation in the allele and haplotype distribution between the six Pakistani ethnic groups was observed. A phylogenetic tree and correspondence analysis based on HLA-A, -B, -C, -DRB1 and -DQB1 allele frequencies revealed the Kalash population to be distinct from the remaining Pakistani populations. The Baloch and Brahui were closely related to one another. The Sindhi were closer to the Pathan and Burusho populations than to the neighboring Baloch and Brahui populations, indicating admixture between the northern and southern populations of Pakistan. A phylogenetic tree and correspondence analysis comparing the Pakistani populations with various other world populations showed that the Pakistani ethnic groups lie within the cluster of Asian Indian populations. The three-locus haplotypes found in the Pakistani populations suggest an influence from Caucasian and Oriental populations.

Ethnicity↗
PubMed1984

HLA polymorphisms in a Shanghai Chinese population.

The frequencies of the HLA-A, B, C, D, DR and MB antigens have been determined in a homogeneous Shanghai Chinese population. Comparisons with the HLA-A and -B frequencies in other subsets of the Chinese population revealed some marked differences. No comparisons were possible for the D, DR and MB antigens since there were no previous studies of the antigens in those loci. We suggest that studies of the Chinese population should be confined to clearly defined homogeneous subsets. In this manner, the confounding effect of population heterogeneity may be avoided, and it is this heterogeneity which calls for extensive surveys of the huge Chinese population.

Asian People↗
PubMed2005

HLA polymorphisms in Cabo Verde and Guiné-Bissau inferred from sequence-based typing.

Human leukocyte antigen (HLA)-A, -B, and -DRB1 polymorphisms were examined in the Cabo Verde and Guiné-Bissau populations. The data were obtained at high-resolution level, using sequence-based typing. The most frequent alleles in each locus was: A*020101 (16.7% in Guiné-Bissau and 13.5% in Cabo Verde), B*350101 (14.4% in Guiné-Bissau and 13.2% in Cabo Verde), DRB1*1304 (19.6% in Guiné-Bissau), and DRB1*1101 (10.1% in Cabo Verde). The predominant three loci haplotype in Guiné-Bissau was A*2301-B*1503-DRB1*1101 (4.6%) and in Cabo Verde was A*3002-B*350101-DRB1*1001 (2.8%), exclusive to northwestern islands (5.6%) and absent in Guiné-Bissau. The present study corroborates historic sources and other genetic studies that say Cabo Verde were populated not only by Africans but also by Europeans. Haplotypes and dendrogram analysis shows a Caucasian genetic influence in today's gene pool of Cabo Verdeans. Haplotypes and allele frequencies present a differential distribution between southeastern and northwestern Cabo Verde islands, which could be the result of different genetic influences, founder effect, or bottlenecks. Dendrograms and principal coordinates analysis show that Guineans are more similar to North Africans than other HLA-studied sub-Saharans, probably from ancient and recent genetic contacts with other peoples, namely East Africans.

Alleles↗
PubMed1988

Maternal-fetal interactions and the maintenance of HLA polymorphism.

There is some empirical evidence that a fetus with an HLA antigen not present in its mother has a higher survival than a fetus sharing antigens with its mother. We have developed both single locus and two-locus theoretical models to examine this mode of selection. First, this immunologically based model appears to have the potential to maintain many alleles at a single locus and to result in an excess of heterozygotes when selection is strong. Second, substantial gametic disequilibrium is maintained between alleles at two loci for this selection mode when recombination is that observed between HLA loci A, B, and DR. Overall, it appears that this mode of selection has the potential to strongly affect genetic variation in the HLA region.

Alleles↗
PubMed1997

HLA class II alleles in Amerindian populations: implications for the evolution of HLA polymorphism and the colonization of the Americas.

The analysis of HLA allele frequencies in various Amerindian populations may shed light on the history of human migrations in the Americas; the overall reduction in the number of alleles relative to non-Amerindian populations and the observation that the same alleles and allelic lineages are "missing" in all Amerindian groups suggests an "Into America" population bottleneck. The identification of previously unreported (and presumably newly arisen) HLA-DRB1 alleles among isolated Amerindian groups, (DRB*0417 in Argentina, *08042 in Ecuador, DRB1*0807 in Brazil, and *0811 in Canada) suggests that these alleles may have been generated since the colonization of the Americas (about 20-30,000 years ago). These observations are difficult to reconcile with the notion, based on the analysis of exon-2 sequences, that most of the human DRB1 alleles are "ancient", that is, predate the divergence of the hominoids (4-7 myr). Recent analyses of DRB1 intron sequences, however, indicate that, although most of the allelic lineages are ancient, the alleles within a lineage (> 90% of the DRB1 alleles) have arisen relatively recently. For DRB1*0807, presumably generated by an Asp to Val change (GAT to GTT) at codon 57, strong selective pressures appear to be in operation, based on the high frequency (23%), and linkage disequilibrium patterns of this allele. The analysis of a complex microsatellite in the second intron in the Ticuna is consistent with the notion that the new Amerindian DR8 alleles arose from DRB1*0802, the only DR8 allele observed in most Amerindian populations.

Alleles↗
PubMed1978

HLA polymorphism in Israel. 4. Israeli Jews originating from Rumania.

The frequencies of 29 HLA antigens of the A amd B loci were studied in 130 Israeli Jews originating from Rumania. The antigens A1, A2, Aw19 and B14, Bw16 and Bw35 occurred with the highest frequencies. The most common haplotypes were (A1, B17), (Aw26, Bw16) and (A28, Bw22). These results are similar to those observed in Polish and Russian Jews.

Gene Frequency↗
PubMed1992

[HLA polymorphism in the susceptibility or resistance to dilated cardiomyopathy].

Much of the surrounding studies on the association between HLA and diseases reflects a new insight into the key role of HLA molecules in the generation and regulation of the immune response. HLA molecules, on the surface of antigen presenting cells, bind foreign peptides. This HLA-antigen complex is then recognized by T lymphocytes and triggers the alloresponse against the peptide. Since many diseases associated with peculiar HLA antigens are thought to be autoimmune, the idea that certain Major Histocompatibility Complex (MHC) molecules could form complexes with self-peptides in anomalous ways, leading to an autoimmune reaction, is particularly attractive. Recent advances in molecular technology, x-ray crystallography and DNA studies have allowed the determination of the three-dimensional structure of some HLA class I and II molecules and also the amino acid sequences involved in binding of antigen fragments. This new information has prompted a search for differences, at the amino acid level, between HLA alleles previously shown to be positively or negatively associated with a pathology. Our own experience on the immunogenetic aspect of dilated cardiomyopathy (DCM) allowed us to assess some predisposing (HLA-DR4, DR5, C4A4) and protective (HLA-DR3) factors for DCM. Clinical heterogeneity also seems to imply a peculiar genetic background. The actual research is addressed to the study of the antigen binding site sequences and to the consideration of other new loci such as those entrapped within the HLA class III subregion (HSP70) and those lying within the class II region (PSF).

Cardiomyopathy, Dilated↗
PubMed2002

HLA polymorphism in Bulgarians defined by high-resolution typing methods in comparison with other populations.

In the present study we analyzed for the first time HLA class I and class II polymorphisms defined by high-resolution typing methods in the Bulgarian population. Comparisons with other populations of common historical background were performed. Most HLA-A, -B, -DRB alleles and haplotypes observed in the Bulgarian population are also common in Europe. Alleles and haplotypes considered as Mediterranean are relatively frequent in the Bulgarian population. Observation of Oriental alleles confirms the contribution of Asians to the genetic diversity of Bulgarians. The use of high-resolution typing methods allowed to identify allele variants rare for Europeans that were correlated to specific population groups. Phylogenetic and correspondence analyses showed that Bulgarians are more closely related to Macedonians, Greeks, and Romanians than to other European populations and Middle Eastern people living near the Mediterranean. The HLA-A,-B,-DRB1 allele and haplotype diversity defined by high-resolution DNA methods confirm that the Bulgarian population is characterized by features of southern European anthropological type with some influence of additional ethnic groups. Implementation of high-resolution typing methods allows a significantly wider spectrum of HLA variation to be detected, including rare alleles and haplotypes, and further clarifies the origin of Bulgarians.

Bulgaria↗
PubMed1978

HLA polymorphism in Israel. 8. The Armenian community in Jerusalem.

Gene and phenotype frequencies for the three HLA loci were determined for 90 random Armenians from the Old City of Jerusalem. Relatively high frequencies were found for HLA-A2, A3 and Aw24, while the lowest frequencies were those for Aw23 and Aw25. The major distinguishing antigen, when compared with European Caucasoids is Bw35 with a frequency of 22%. Two unusual associations between the B and C loci were observed: Bw 17, Cw3 and B7, Cw3. Another interesting association in Armenians, Aw32 Cw4, has previously been found only among Cochini Jews and Malay populations.

Armenia↗
PubMed1983

Segregation and mapping analysis of polymorphic HLA class I restriction fragments: detection of a novel fragment.

An HLA-B7 complementary DNA clone was used as a hybridization probe to analyze the segregation pattern of polymorphic class I restriction fragments in several families whose HLA types had been determined by serological techniques. In one family in which a crossover in the HLA region had occurred, a specific genomic fragment was mapped with respect to the crossover. In another family, a novel genomic fragment present in one child and absent in all other family members was observed. With the exception of this novel fragment, all polymorphic class I fragments observed in this study segregated with a serologically defined parental haplotype, a result consistent with HLA linkage.

Chromosome Mapping↗
PubMed1990

[Population genetics of HLA polymorphism in blood donors of Bremen and Hannover].

501 blood donors from Bremen have been typed for HLA-ABC and -DR. The results are compared with HLA data obtained on 474 blood donors from Hannover. The gene frequencies do not differ significantly between these two population samples. Comparisons with population samples from Kiel, Hamburg, Essen, Frankfurt/M., Mainz, Mannheim, Freiburg/Br., Munich and Vienna did also not reveal any remarkable differences concerning the gene frequencies. Analysis of linkage disequilibrium of two-factor and three-factor haplotypes could show that the typical Caucasoid allele combination A1/B8 is not a constituent part of three-factor haplotype combinations. Between the population samples from Bremen and Hannover no marked differences in the distribution of two-factor and three-factor haplotype frequencies could be found.

Adult↗
PubMed2001

HLA polymorphism in the Murcia population (Spain): in the cradle of the archaeologic Iberians.

Human leukocyte antigen (HLA) study in Murcian individuals was performed in order to provide information of their historical origins and relationships with other Iberian and Mediterranean populations. HLA class I and class II alleles were determined in 173 unrelated Caucasoid donors from Murcia Region in the Southeast of Spain by serologic and DNA based polymerase chain reaction (PCR) typing. Class I antigen and class II allele frequencies of our series were not very different to those found in Spaniards. The analysis of extended haplotypes showed that the three haplotypes most frequent in our population were respectively, A29-B44-Cwb-DRB1*0701-DRB4*0101-DQA1*0201-DQB1*0202, A1-B8-Cw7-DRB1*0301-DRB3*0101-DQA1*0501-DQB1*0201 and A30-B18-Cw5-DRB1*0301-DRB3*0101-DQA1*0501-DQB1*0201. They were followed by A26-B38-Cwb-DRB1*1301-DRB3*0202-DQA1*0103-DQB1*0603, which could point to an ancestral relationship between Murcian and Portuguese Iberian populations, and by A2-B7-Cw7-DRB1*1501-DRB5*0101-DQA1*0102-DQB1*0602 also present in all Iberian Peninsula populations. Allelic frequencies, populations distance dendrogram and correspondence analysis were used to study the relationships between Murcian and other populations. The closest relation was observed with Spaniards and Portuguese, followed in decreasing order by French, Italians, Algerians, Germans, Catalans, Basques, Cretans, Sardinians, and Greeks. Thus, Murcian population seems to belong to the European genetic pool, revealing a lesser genetic distance with the North Africans and the rest of populations from the Iberian Peninsula.

Africa↗
PubMed1993

The HLA polymorphism of two distinctive South-American Indian tribes: the Kaingang and the Guarani.

The HLA-A, B, C, DR and DQ antigens of 240 Kaingang and 98 Guarani individuals have been characterized. The most frequent antigens found among the Kaingang are A31, 2, 24; B35, 51, 39, 48; Cw4, 7, 3, 1; DR8, 4, 2; DQ blank, 3. In the Guarani, they are A2, 28, 31; B40, 62, "53G"; Cw3, 4; DR2, 4, 8, 6; DQ3, blank. B " 53G" is an unusual antigen of the B5 cross-reactive group. DQ blank possibly corresponds to DQ4, not tested in this study. The reaction patterns of B35, B40 and DR4 indicate intra-tribal (of B35 and B40), and inter-tribal (DR4, B40 and B35) heterogeneity of these antigens. 408 Kaingang and 141 Guarani haplotypes were defined by segregation analysis. Of the commonest 10 Guarani and 9 Kaingang haplotypes, only one is shared by both tribes. Significant, positive linkage disequilibrium values for HLA-A,B; HLA-A,C; HLA-B,DR and most HLA-B,C antigen pairs were also different for the two populations. Genetic distance estimates between these two and another seven South-American Indian populations, and relative to the major human races (negroids, caucasoids, and mongoloids) reveal a comparatively high degree of divergence between the Kaingang and the Guarani, which is uncommon for Amerindian populations living close one to another.

Alleles↗