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Results for “HLA polymorphism”

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At least 73 records · Page 4Linked to original sources
PubMed1993

HLA polymorphism in the Havasupai: evidence for balancing selection.

The characterization and analysis of genetic variation at the HLA loci provides important insight for population geneticists trying to understand the evolutionary forces that have shaped human populations. This study describes the HLA-A and HLA-B loci serotyping and statistical analysis on an isolated Native American population, the Havasupai of Arizona. Four alleles at the HLA-A locus were identified, while eight alleles were found at the HLA-B locus. These variants were present as 20 of 32 potential two-locus haplotypes, with five of the six most common haplotypes exhibiting high positive linkage disequilibrium. Significant homozygote deficiency (heterozygosity excess) was detected both at HLA-A and at HLA-B. This deviation from Hardy-Weinberg proportions was not attributable to nonselective causes such as different allele frequencies in males and females or avoidance of consanguineous matings. In addition, the distribution of alleles at both HLA-A and HLA-B was more even than expected from neutrality theory; that is, the observed Hardy-Weinberg homozygosity was only 62.4% of that expected under neutrality. These observations suggest that balancing selection is of major importance in maintaining genetic variation at HLA-A and HLA-B.

Female↗
PubMed1978

HLA polymorphism in Israel. 6. North African Jews from Libya.

Phenotype and gene frequencies of antigens at the A and B HLA loci were determined in a sample of 89 random Libyan Jews now settled in Israel. Most antigens at the A locus are within the range found in European populations while, at the B locus, the frequencies differ from Caucasoid populations: B7 is usually rare (1%), Bw35 is frequent (14%) and Bw40 very common with more than 10%. Thirteen percent of Libyan women whose sera were screened for the presence of HLA antibodies gave positive results. Some of them are elderly women, about 15 years or more beyond their last birth.

Gene Frequency↗
PubMed2005

[HLA polymorphism in a racially admixed sample of the population of Teresina, Piauí].

OBJECTIVE: To establish the frequencies of HLA-A, B, DRB1 and DQB1 specificities in a racially admixed sample of the city of Teresina, Piauí to characterize its genetic composition. METHODS: Polymerase chain reaction-sequence specific primers (PCR-SSP) were used to determine HLA-A, B, DRB1 and DQB1 specificities of 97 unrelated healthy racially admixed people of Teresina. The genotypic frequencies were estimated and compared to those described in samples of Brazilian Caucasian, Portuguese, Black and Amerindian populations using Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA). RESULTS: The frequencies of HLA-A, B, DRB1 and DQB1 specificities observed in the study sample were intermediate between Blacks and Caucasians and the typical elevation of HLA-specificities seen in the Amerindian race was not observed in the study population. The PCA and HCA analysis revealed that Teresina's racially admixed are very close to both Black and Caucasian and do not show similarities with the Amerindians. CONCLUSION: The genetic composition of Teresina's racially admixed is predominantly bi-hybrid of genes originated from Blacks and Caucasians with little contribution from Amerindian genes.

Brazil↗
PubMed2003

Detection of HLA polymorphisms by ligase detection reaction and a universal array format: a pilot study for low resolution genotyping.

We present our results in the identification of polymorphic sites within the second exon of the human leukocyte antigen A (HLA-A) region using the DNA microarray technology. Allele specific detection was performed by polymerase chain reaction followed by ligase detection reaction (LDR) in combination with a universal array, a powerful method for high throughput DNA sequence analysis. By this approach we confirmed 32 human samples previously characterized by direct DNA sequencing, thus demonstrating the interest of this approach.

DNA Ligases↗
PubMed2007

Relationship between HLA polymorphisms and gamma interferon and interleukin-10 cytokine production in healthy individuals after rubella vaccination.

We studied the association between HLA alleles and rubella-specific gamma interferon (IFN-gamma) (Th1) and interleukin-10 (IL-10) (Th2) cytokine responses among 106 healthy children (ages, 14 to 17 years) previously immunized with two doses of rubella vaccine. Antibody titers and cytokine responses to rubella vaccination were not sex or age dependent. Several class I HLA-A (*0201, *2402, *6801) alleles were significantly associated with rubella vaccine-induced IFN-gamma secretion. Several class II HLA-DRB1 (*0101) and HLA-DQB1 (*0501) alleles were also suggestive of an association with IFN-gamma secretion. Alleles with potential associations with rubella-specific IL-10 production included HLA-A (*0201, *6801), HLA-B (*4901), and HLA-DRB1 (*1302). The class I A*0201 and A*6801 alleles were associated with both IFN-gamma and IL-10 secretion. These tentative associations need to be validated in larger studies with subjects of differing ethnicities. These results provide additional evidence that HLA genes may influence Th1- and Th2-specific cytokine response(s) following rubella immunization, which in turn can influence both cellular and humoral immune responses to rubella vaccination.

Adolescent↗
PubMedDate not supplied

The HLA polymorphism in five Brazilian populations.

A total of 977 White individuals living in five Brazilian cities, as well as 173 Black individuals from two of these cities have been studied in relation to HLA-A and HLA-B. Allele frequency similarities among these populations are much more impressive than dissimilarities, and the differences, considering putative ancestors, are not remarkable. This limited variability can be only partially explained in terms of racial admixture, estimates of the latter using different alleles in the various populations showing disparate results. Linkage disequilibrium values vary between groups, that for A1-B8 being the most consistent, independent of sample or race. But four other haplotypes observed to be in significant disequilibrium in Portugal showed the same pattern in at least one of the five Brazilian White samples.

Adult↗
PubMed1976

The HLA polymorphism and susceptibility to disease.

Remarkable differences were observed when 1,465 healthy Caucasian individuals and 128 healthy Negro individuals were compared for the genetic distribution of 25 different HLA antigens. Caucasians had a significantly higher frequency of A1, A3, B8, and Bw16, and Negroes of A28 and Aw30. The haplotype which had the highest incidence as well as the greatest positive linkage disequilibrium was A1-B8 among Caucasians and A2-B12 among Negroes. Genetic distance between the two races was 0.0592. The 89 Caucasian patients with renal failure did not demonstrate any significant deviations in phenotype frequencies (PF) of various antigens, when compared with healthy Caucasians; however, 48 similar Negro patients had twice as high an incidence of Bw17 as the healthy Negroes. No significant deviation in PF was observed in 77 Caucasian patients who had leukemia; however, 32 Caucasian patients who had back pain (24 also had back stiffness) due to spondylitic, arthritic or disc syndrome, had a significant increase of Bw16 and of B27, and a decrease of B12, when compared to Caucasian controls.

ABO Blood-Group System↗
PubMed2002

Influence of HLA polymorphism on persistent remission in rheumatoid arthritis.

BACKGROUND: Several studies have reported an association between the presence of the shared epitope (SE) and susceptibility to rheumatoid arthritis (RA). Recent studies have shown that certain HLA-DRB1 alleles in combination with predisposing DQB1 and DQA1 alleles may protect against the development of RA. This model is known as the rheumatoid arthritis protection (RAP) hypothesis. OBJECTIVE: To determine the distribution of HLA-DRB1 and DQB1/DQA1 alleles in a cohort of patients with RA in remission and to determine the association between these HLA alleles and the persistence of remission. PATIENTS AND METHODS: HLA-DRB1 and DQB1 typings were performed in 167 patients with RA in remission, defined according to the American College of Rheumatology criteria. The disease course, as defined by the persistence of remission during a follow up of two years, was compared between subgroups. According to the RAP hypothesis patients were divided into three subgroups: patients carrying predisposing DQ alleles, patients carrying predisposing alleles in combination with protective alleles (DQ(RA+)/DERAA phenotype), and patients lacking the predisposing alleles. According to the SE hypothesis, patients were divided into three subgroups based on whether they were carrying two, one, or no predisposing alleles (SE alleles). RESULTS: Predisposing DQ alleles along with a DERAA-bearing allele were present in 14 (8%) of the 167 patients. At least one SE allele was present in 116 (69%) patients; 34 of them (20%) were carrying two copies. The disease course was not significantly different between the subgroups according to the SE and RAP hypothesis, respectively. CONCLUSION: The frequency of DQ(RA+)/DERAA combinations and of SE alleles in patients with RA clinically in remission was similar to that found in other RA populations. Persistent remission of RA was not associated with any particular HLA subtypes, indicating that HLA typing is not useful for predicting persistent clinical remission.

Antirheumatic Agents↗
PubMed1992

Oligonucleotide genotyping of HLA polymorphism on microtitre plates.

Molecular analysis of mutations and polymorphisms that are of medical importance requires both accuracy and simplicity. In organ transplantation there is a need for an HLA typing procedure that combines the remarkable accuracy of oligonucleotide genotyping with the simplicity of conventional serological typing. We describe a simple semiautomated method of HLA class II typing consisting of an oligonucleotide hybridisation assay done on microtitre plates followed by automatic colorimetric reading. Individual HLA-DR generic typing for 30 DR specificities, including subtypes of DR1, DR2, DR13, DR14, and DR52, is done on a single plate. The entire typing assay can be completed in less than 4 hours. The procedure has been validated on more than a thousand haplotypes in prospective DR typing of kidney transplant patients, leukaemic patients, and their potential donors. The simplicity of this assay makes it suitable for routine laboratory use. It can be applied to genetic testing in general, including the testing of patients with multiple mutations.

Base Sequence↗
PubMed1980

Human cytotoxic T-cell responses to type A and type B influenza viruses can be restricted by different HLA antigens. Implications for HLA polymorphism and genetic regulation.

The present study compares human cytotoxic T-cell responses to two closely related viruses (type A and type B influenza) to understand the antigen-specific elements involved in HLA-linked genetic control of cytotoxic T-cell responses. The HLA antigens function as self antigens that are recognized by cytotoxic T cells sensitized against either virus. However, studies in an informative family indicate that in this family, the HLA antigens preferentially recognized in conjunction with type A influenza (A/HK) differ from the HLA antigens preferentially recognized in conjunction with type B influenza (B/HK). Similarly, population studies demonstrate that some (but not all) donors whose T cells recognized A/HK in conjunction with HLA-A2 failed to recognize B/HK in conjunction with HLA-A2. Thus, HLA-linked regulation must operate by a mechanism(s) that is specific both for the self HLA antigen and the viral antigen. Furthermore, these findings indicate that different HLA antigens may facilitate T-cell responses to different pathogens, which would result in an evolutionary advantage for HLA heterozygosity.

Cytotoxicity, Immunologic↗
PubMed1984

C3 polymorphism, HLA and chronic renal failure in Spaniards.

C3 allele frequencies were studied in 196 unrelated normal Spaniards. The results fit the Hardy-Weinberg equilibrium. No rare variants were detected. The C3 frequency was close but slightly higher than that found in other Caucasoid populations, and higher than that found in Negroids and Orientals. Spanish Basques also showed a high C3F frequency. A North-South decreasing C3F gradient was recorded and compared to other gradients (HLA-D/DR, height, etc.) thought to be due to natural selection. Lod scores in 28 Spanish families excluded C3 gene assignment at less than 45 cM of HLA/GLO linkage group; no significant linkage disequilibrium was found between C3 and HLA. C3F was also significantly increased in 20 chronic renal failure (CRF) patients as compared to 196 controls; this would support the existence of functional differences between C3F and C3S alleles.

Alleles↗