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Haplotype-specific suppression of antibody responses in vitro. II. Suppressor factor produced by T cells and T cell hybridomas from mice treated as neonates with semiallogeneic spleen cells.

Culture supernatant fluids from spleen cells from C57BL/10 or BALB/c mice neonatally treated with semiallogeneic (B 10.D2 x B10)F1 cells to induce haplotype-specific suppressor T cells and restimulated with macrophages syngeneic at I-A with the allogeneic haplotype encountered as neonates contain a soluble factor capable of suppressing primary in vitro antibody responses of normal syngeneic spleen cells in a non-antigen-specific manner. This haplotype-specific suppressor factor, TsF-H, has also been recovered in culture fluids of a T cell hybridoma produced by fusion of the AKR thymoma BW5147 and the haplotype-specific suppressor T cells. TsF-H is inactivated by low pH (3.5) trypsin, for 30 min at 50 degrees C, and has a molecular weight in the range of 45,000 to 68,000. Studies with specific immunoabsorbents demonstrate the presence of determinants encoded by the I-A subregion of the haplotype of the T cell producing TsF-H but not I-J subregion or immunoglobulin constant-region determinants on the TsF-H. Suppression is restricted to primary in vitro antibody responses, and not secondary antibody, mixed lymphocyte, or cytotoxic lymphocyte responses by spleen cells syngeneic at the I-A subregion of H-2 with the T cell producing the factor. The properties and activities of TsF-H and the haplotype-specific suppressor T cell are compared and contrasted with antigen-specific and genetically restricted suppressor T cells and their factors.

Animals↗

Linkage analysis and molecular haplotyping of the dopamine D4 receptor gene promoter region.

OBJECTIVES: Polymorphic regions of the dopamine D4 receptor gene and its promoter region are in the focus of psychogenetic association studies. Besides the accurate phenotype characterization, highly reliable genotyping methods are also of outstanding importance in these works. METHODS: DNA samples of 598 healthy unrelated Caucasian individuals were used to validate the described molecular haplotyping methods and to determine the allele, genotype and haplotype frequencies and the linkage disequilibrium between the polymorphisms of the dopamine D4 receptor promoter region. RESULTS: We described a double genotyping system for the -521CT and -616CG polymorphisms, using a polymerase chain reaction restriction fragment length polymorphism or an allele-specific amplification. Allele and genotype frequencies of the novel -615AG single-nucleotide polymorphism are also determined (-615G=13.21%). For molecular haplotyping of the three single-nucleotide polymorphisms and a 120-bp duplication polymorphism, the allele-specific amplification was combined with restriction digestion. The results of the elaborated haplotyping methods were validated by molecular haplotyping of cloned fragments. CONCLUSIONS: The developed methods have been arranged into an 'economic' protocol that might be extended for higher reliability with a double haplotyping ('full mode'). Despite the close proximity of these sites, only a moderate linkage was found between the -615AG and -616CG (Delta(2)=0.162), between the -616AG and -521CT (Delta(2)=0.0221) and between the -615AG and -521CT single-nucleotide polymorphisms (Delta(2)=0.0346). The 120-bp duplication was shown to be in linkage equilibrium with any of the three single-nucleotide polymorphisms. Applications of these results should accelerate psychogenetic association studies of the dopamine D4 receptor gene.

Base Sequence↗

The self-incompatibility (S) haplotypes of Brassica contain highly divergent and rearranged sequences of ancient origin.

In Brassica, the recognition of self-related pollen by the stigma is controlled by the highly polymorphic S locus that encodes several linked and coadapted genes and can span several hundred kilobases. We used pulsed-field gel electrophoresis to analyze the structure of different S haplotypes. We show that the S2 and S13 haplotypes of Brassica oleracea contain extensive sequence divergence and rearrangement relative to each other. In contrast, haplotypic configuration is more conserved between B. oleracea S13 and B. campestris S8, two haplotypes that have been proposed to be derived from a common ancestral haplotype based on sequence comparisons. These results support the view that extensive restructuring of the S locus preceded speciation in Brassica. This structural heteromorphism, together with haplotype-specific sequences, may suppress recombination within the S locus complex, potentially providing a mechanism for maintaining the linkage of coadapted allelic combinations of genes over time.

Brassica↗

Total blood lymphocyte counts in hemochromatosis probands with HFE C282Y homozygosity: relationship to severity of iron overload and HLA-A and -B alleles and haplotypes.

BACKGROUND: It has been reported that some persons with hemochromatosis have low total blood lymphocyte counts, but the reason for this is unknown. METHODS: We measured total blood lymphocyte counts using an automated blood cell counter in 146 hemochromatosis probands (88 men, 58 women) with HFE C282Y homozygosity who were diagnosed in medical care. Univariate and multivariate analyses of total blood lymphocyte counts were evaluated using these variables: sex; age, transferrin saturation, and serum ferritin concentration at diagnosis; units of blood removed by phlebotomy to achieve iron depletion; and human leukocyte antigen (HLA)-A and -B alleles and haplotypes. RESULTS: The mean age at diagnosis was 49 +/- 14 years (range 18 - 80 years) in men and 50 +/- 13 years (range 22-88 years) in women. The correlations of total blood lymphocyte counts with sex, age, transferrin saturation, and serum ferritin concentration at diagnosis, and units of blood removed by phlebotomy to achieve iron depletion were not significant at the 0.05 level. Univariate analyses revealed significant associations between total blood lymphocyte counts and presence of the HLA-A*01, -B*08, and -B*14 alleles, and the A*01-B*08 haplotype. Presence of the A*01 allele, B*08 allele, or A*01-B*08 haplotype were associated with a lower total blood lymphocyte count, whereas presence of the B*14 allele was associated with a greater total blood lymphocyte count. There was an inverse association of total blood lymphocyte count with units of phlebotomy to achieve iron depletion, serum ferritin concentration, and with presence of the A*01-B*08 haplotype. CONCLUSION: We conclude that there is a significant inverse relationship of total blood lymphocyte counts and severity of iron overload in hemochromatosis probands with HFE C282Y homozygosity. The presence of the HLA-A*01 allele or the -B*08 allele was also associated with significantly lower total blood lymphocyte counts, whereas presence of the -B*14 allele was associated with significantly higher total blood lymphocyte counts. In univariate and multivariate analyses, total blood lymphocyte counts were significantly lower in probands with the HLA-A*01-B*08 haplotype than in probands without this haplotype.

Journal Article↗

In adult onset myositis, the presence of interstitial lung disease and myositis specific/associated antibodies are governed by HLA class II haplotype, rather than by myositis subtype.

The aim of this study was to investigate HLA class II associations in polymyositis (PM) and dermatomyositis (DM), and to determine how these associations influence clinical and serological differences. DNA samples were obtained from 225 UK Caucasian idiopathic inflammatory myopathy patients (PM = 117, DM = 108) and compared with 537 randomly selected UK Caucasian controls. All cases had also been assessed for the presence of related malignancy and interstitial lung disease (ILD), and a number of myositis-specific/myositis-associated antibodies (MSAs/MAAs). Subjects were genotyped for HLA-DRB1, DQA1 and DQB1. HLA-DRB1*03, DQA1*05 and DQB1*02 were associated with an increased risk for both PM and DM. The HLA-DRB1*03-DQA1*05-DQB1*02 haplotype demonstrated strong association with ILD, irrespective of myositis subtype or presence of anti-aminoacyl-transfer RNA synthetase antibodies. The HLA-DRB1*07-DQA1*02-DQB1*02 haplotype was associated with risk for anti-Mi-2 antibodies, and discriminated PM from DM (odds ratio 0.3, 95% confidence interval 0.1-0.6), even in anti-Mi-2 negative patients. Other MSA/MAAs showed specific associations with other HLA class II haplotypes, irrespective of myositis subtype. There were no genotype, haplotype or serological associations with malignancy. The HLA-DRB1*03-DQA1*05-DQB1*02 haplotype associations appear to not only govern disease susceptibility in Caucasian PM/DM patients, but also phenotypic features common to PM/DM. Though strongly associated with anti-Mi-2 antibodies, the HLA-DRB1*07-DQA1*02-DQB1*02 haplotype shows differential associations with PM/DM disease susceptibility. In conclusion, these findings support the notion that myositis patients with differing myositis serology have different immunogenetic profiles, and that these profiles may define specific myositis subtypes.

Adult↗

Allelic and haplotypic diversity at the rp1 rust resistance locus of maize.

The maize Rp1 rust resistance locus is a complex consisting of a family of closely related resistance genes. The number of Rp1 paralogs in different maize lines (haplotypes) varied from a single gene in some stocks of the inbred A188 to >50 genes in haplotypes carrying the Rp1-A and Rp1-H specificities. The sequences of paralogs in unrelated haplotypes differ, indicating that the genetic diversity of Rp1-related genes is extremely broad in maize. Two unrelated haplotypes with five or nine paralogs had identical resistance phenotypes (Rp1-D) encoded in genes that differed by three nucleotides resulting in a single amino acid substitution. Genes in some haplotypes are more similar to each other than to any of the genes in other haplotypes indicating that they are evolving in a concerted fashion.

Base Sequence↗

A method for evaluating the impact of individual haplotypes on disease incidence in molecular epidemiology studies.

Estimation of the association between haplotypes and disease from a case-control study is considered. Assuming a single "disease haplotype'' leads to the increased risk, attention focusses on the relative risks associated with a single copy, or two copies of the disease haplotype, relative to individuals with no copies. In this setting, case frequencies of the haplotype pairs are in Hardy-Weinberg Equilibrium (HWE) only if the combined influence of the two copies of the disease haplotype on risk is multiplicative. Thus, imputation cannot rely on the assumption of HWE for cases. A method is presented for obtaining estimates of the relative risks, making use of the EM algorithm and the assumption of HWE only for controls. The method accounts for the additional variation in the estimates due to the imputation of expected frequencies of haplotype pairs from ambiguous genotypes. A simulation study shows that the resulting confidence intervals have nominal coverage, and that the methods based on the assumption of HWE for both cases and controls can lead to bias.

Journal Article↗

Multi-SNP analysis of MHC region: remarkable conservation of HLA-A1-B8-DR3 haplotype.

Technology has become available to cost-effectively analyze thousands of single nucleotide polymorphisms (SNPs). We recently confirmed by genotyping a small series of class I alleles and microsatellite markers that the extended haplotype HLA-A1-B8-DR3 (8.1 AH) at the major histocompatibility complex (MHC) is a common and conserved haplotype. To further evaluate the region of conservation of the DR3 haplotypes, we genotyped 31 8.1 AHs and 29 other DR3 haplotypes with a panel of 656 SNPs spanning 4.8 Mb in the MHC region. This multi-SNP evaluation revealed a 2.9-Mb region that was essentially invariable for all 31 8.1 AHs. The 31 8.1 AHs were >99.9% identical for 384 consecutive SNPs of the 656 SNPs analyzed. Future association studies of MHC-linked susceptibility to type 1 diabetes will need to account for the extensive conservation of the 8.1 AH, since individuals who carry this haplotype provide no information about the differential effects of the alleles that are present on this haplotype.

Diabetes Mellitus, Type 1↗

[Single nucleotide polymorphism and haplotype in TBX1 gene of patients with conotruncal defects: analysis of 130 cases].

OBJECTIVE: To investigate the distribution of the single nucleotide polymorphism (SNP) sites in TBX1 gene and the distribution of related haplotypes in the patients with conotruncal defects (CTD) and normal people. METHODS: The genotypes of the 3 selected SNPs: G2857C (rs737868), G2963A (rs28649236), and A6571T (rs28939675) in TBX1 gene were analyzed by PCR-RFLP among 130 patients with CTD and 200 normal people. Contingency table was applied to analyze the frequencies of these SNP genotypes and related alleles. PHASE software was used to construct the haplotypes and analyze the haplotype frequencies in these 2 groups. RESULTS: There were no significant differences in the allele frequency and genotype rates of the SNPs G2587C and A6571T between the CTD patients and normal controls (all P > 0.05). However, the allele frequency and genotype rates of the SNP G2963A were significant different between he CTD patients and normal controls: the G allele frequency in the CTD patients was 53.8%, significantly higher than that in the normal controls (42.5%, chi(2) = 8.14, P < 0.005); and the AA genotype rate of the CTD patients was 21.6%, significantly lower than that of the controls (38.0%), and the GA genotype rate in the CTD patients was 49.2%, significantly higher than that in the controls (39.0%) (both chi(2) = 9.9, P < 0.05). The haplotype frequencies of G2587/G2963/A6571 and G2587/A2963/T6571 of the CTD patients were 49.2% and 14.6% respectively, both significantly higher than those of the normal controls (36.3% and 9.5% respectively), and the haplotype frequencies of G2587/G2963/T6571 and G2587/A2963/A6571 in the CTD patients were 34.6% and 3% respectively, both significantly lower than those in the normal controls (48.3% and 18% respectively) (chi(2) = 22.39, P < 0.005). CONCLUSION: The SNP site G2963A located in the coding-region of TBX1 gene is associated with CTD. The persons with G2963 have higher risk of CTD than those with A2963. The haplotypes constructed with these 3 SNP sites may be linked with the susceptibility gene of CTD.

Adolescent↗

Extended haplotypes in rheumatoid arthritis and preliminary evidence for an interaction with immunoglobulin genes.

The incidence of extended haplotypes of the Major Histocompatibility Complex was compared between 20 probands with RA, their unaffected family members, and 42 controls. One haplotype only, HLA-Bw62 BfS C4A*3 C4B*3 DR4 GLO2, was significantly increased in the patient group, whereas HLA-B7 BfS C4A*3 C4B*1 DR2 GLO1, which was the most common haplotype in the control groups, was absent. The immunoglobulin allotype Glm(2) was significantly increased in frequency in the RA patients, and analysis showed that of the seven patients carrying Bw62-DR4, five were G1m(2) positive. Further, the increase in frequency of the phenotype Gm(1,2,17,21,3,5,23) was also significant and was carried by two of four probands with the extended haplotype HLA-Bw62 BfS C4A*3 C4B*3 DR4 GLO2 and by one proband also bearing this haplotype but with a null allele at the C4A locus. The striking association of G1m(2) and Bw62 with DR4 in our patients suggests that in interaction of immunoglobulin genes with DR4 is stronger when DR4 is associated with particular haplotypes rather than with DR4 in general.

Arthritis, Rheumatoid↗

Biochemistry of HLA-DRw6: evidence for seven distinct haplotypes.

The DRw6 specificity, which has a frequency of 11% in the Caucasian population, cannot be positively defined, since no monospecific allo-antiserum is available. This particular status among DR specificities led us to study the DRw6 haplotypes at the molecular level. We performed 2D-PAGE analysis of HLA-DR molecules in 44 different DRw6 haplotypes. The data were obtained from six homozygous typing cells, eight families informative for the segregation of the DRw6 haplotype, and 15 unrelated donors. Five unique beta-chain electrophoretic patterns were detected, indicating the existence of five structurally distinct DRw6 beta-chains. Each haplotype expresses one or two beta-chains. The different combinations of the DR beta-chains present in a single haplotype allow to characterize seven unique DRw6 haplotypes. In contrast to what has been previously found for DR2 and DR4, there is no DR beta-chain common to all the DRw6 cells. Correlation of the biochemical data with the recent serologic (DRw13 vs DRw14) and cellular (Dw9, Dw18, Dw19) splits of the DRw6 specificity will be discussed.

Antibodies, Monoclonal↗

Identical RT1 class II molecules are expressed by rat RT1m and RT1c haplotypes.

The RT1m haplotype of MNR rats has been suggested to be a recombinant RT1 haplotype inheriting RT1.A (class I) alleles from RT1a (DA) and RT1.B (class II) alleles from RT1c (AUG). Additional serologic and biochemical assays, however, have suggested that RT1m and RT1c share a single identical RT1.B molecule, although differing in the expression of the second RT1.B molecule. To resolve this contradiction, RT1.B class II molecules, comparable to I-A and I-E molecules in mice, expressed by the RT1c and RT1m haplotypes were immunoprecipitated by cross-reactive mouse anti-Ia antibodies and were compared by two-dimensional gel electrophoresis and by high pressure liquid chromatographic separation of tryptic peptides. Respective subunits expressed by the two haplotypes co-migrate on two-dimensional gels and have identical tryptic peptide maps. The results at the protein level were confirmed at the DNA level by Southern blot analysis of MNR and AUG genomic DNA. Identical restriction fragments associated with the RT1m and RT1c haplotypes hybridized with each of the DC1 beta, DR alpha, and DR beta cDNA probes. The results at both the protein and DNA levels suggest that the RT1m and RT1c haplotypes share identical expressed alleles at the RT1.Ba, RT1.Bb, RT1.Bc, and RT1.Bd loci.

Animals↗

HLA/Bf haplotypes in a Newfoundland family.

HLA/Bf haplotypes were examined in a large three-generation Newfoundland family with a high incidence of Graves' disease. In that family Graves' disease was inherited in association with the haplotype HLA Aw24, Bw39 in some instances and with HLA B8-containing haplotypes in other instances. As all seven members of the family who suffered from Graves' disease were homozygous for the Bf S allele, the study for Bf was uninformative. However, the examination of other HLA/Bf haplotypes disclosed some interesting associations. One-hundred-and-five out of 168 HLA-A, -B, -Bf haplotypes were Bf S. Although numerically deviant, no unusual HLA B/Bf associations were observed. Bf F entered the family only once. A new finding is the association between HLA B27 and Bf S1; the haplotype entered the family once and was passed on to eight family members over three generations. Bf S1 was previously reported in association with HLA B12 or W21. None of these family members had ankylosing spondylitis. The Bf allele F1 entered the family three times, always in association with HLA B18.

Alleles↗

Specific haplotype preference in congenic F1 hybrid mice in the cytotoxic T cell response to the male specific antigen H-Y.

Haplotype preference in the cytotoxic T cell response to H-Y in B10 congenic mice is only found in (B10 X B10.S)F1 hybrids. (B10 X B10.BR)F1 and (B10 X B10.D2)F1 do not generally show haplotype preference. H-2s is the preferred haplotype in H-Y immune (B10 X B10.S)F1 Tc cells. This haplotype preference is antigen specific since no preference was observed in the anti-influenza responses in (B10 X B10.S)F1 hybrids. Feedback inhibition as an explanation for haplotype preference could be excluded, but cross-reactivity of B10 H-Y immune Tc cells on B10.S targets suggests that natural tolerance may be responsible for haplotype preference.

Animals↗

Genetic heterogeneity of insulin-dependent (type I) diabetes mellitus: evidence from a study of extended haplotypes.

Two hundred subjects with insulin-dependent (type I) diabetes mellitus (IDDM) were typed for HLA-B, HLA-DR, and properdin factor B (Bf). HLA and Bf antigen and haplotype frequencies in subjects were compared with control frequencies derived from the 8th HLA Workshop. Frequencies of extended haplotypes (defined by B-Bf-DR alleles on a chromosome) were also contrasted with control frequencies. Significant positive associations between IDDM and HLA-B8, DR3, DR4, BfS, and BfF1 were confirmed, as were significant negative associations between IDDM and HLA-B7, DR2, DR5, DR7, and BfF. One haplotype (B7-BfS-DR2) exhibited significant negative association, while five haplotypes (B8-BfS-DR3, B8-BfS-DR4, B15-BfS-DR4, B18-BfF1-DR3, and B40-BfS-DR4) exhibited significant positive associations with IDDM. In this sample, 64% of all probands carried at least one of the high-risk haplotypes. In conclusion, the occurrence of five "high-risk" haplotypes associated with IDDM provides evidence for previously undocumented genetic heterogeneity and suggests that possibly more than two HLA-region genes may be involved in IDDM susceptibility.

Adolescent↗

Interrelationships between Amerindian tribes of lower Amazonia as manifest by HLA haplotype disequilibria.

HLA B-C haplotypes exhibit common disequilibria in populations drawn from four continents, indicating that they are subject to broadly active selective forces. However, the A-B and A-C associations we have examined show no consistent disequilibrium pattern, leaving open the possibility that these disequilibria are due to descent from common progenitors. By examining HLA haplotype distributions, I have explored the implications that would follow from the hypothesis that biological selection played no role in determining A-C disequilibria in 10 diverse tribes of the lower Amazon Basin. Certain haplotypes are in strong positive disequilibria across a broad geographic area, suggesting that members of diverse tribes descend from common ancestors. On the basis of the extent of diffusion of the components of these haplotypes, one can estimate that the progenitors lived less than 6,000 years ago. One widely encountered lineage entered the area within the last 1,200 years. When haplotype frequencies are used in genetic distance measurements, they give a pattern of relationships very similar to that obtained by conventional chord measurements based on several genetic markers; but more than that, when individual haplotype disequilibria in the several tribes are compared, multiple origins of a single tribe are discernible and relationships are revealed that correlate more closely to geographic and linguistic patterns than do the genetic distance measurements.

Brazil↗

Gammaglobulin groups of the Khoisan peoples of Southern Africa: evidence for polymorphism for a Gm1,5,13,14,21 haplotype among the San.

The Gm and Inv types were determined for eight San (Bushman) populations, two Khoikhoi (Hottentot) populations, one Coloured population, 112 San families in which the genotypes of the parents could be unambiguously determined, and for 65 San families in which the genotype of one or both parents could not be determined with certainty. The population and family data establish that the haplotype array of the San is composed of Gm1,21, Gm1,13, Gm1,5,13,14, and Gm1,5,13,14,21; Gm1,5,6 and Gm1,5,6,14 are also present but may have been acquired through admixture with Negroes. The Gm1,5,13,14,21 haplotype has not been found to be polymorphic in any other population. The haplotype array of the Khoikhoi is composed of Gm1,2,21, Gm1,13, and Gm1,5,13,14; Gm1,5,6 and Gm1,5,6,14 are also present but, as in the case of the San, may be due to admixture. The San and Khoikhoi differ from each other in that the former have the Gm1,21 and Gm1,5,13,14,21 haplotypes not present in the latter, and the Khoikhoi have the Gm1,2,21 haplotype not present in the San. These three haplotypes and Gm1,13 serve to distinguish the Khoisan people from other African peoples.

Africa, Southern↗

A systematic strategy for identifying causal single nucleotide polymorphisms and their target genes on Juvenile arthritis risk haplotypes.

BACKGROUND: Although genome-wide association studies (GWAS) have identified multiple regions conferring genetic risk for juvenile idiopathic arthritis (JIA), we are still faced with the task of identifying the single nucleotide polymorphisms (SNPs) on the disease haplotypes that exert the biological effects that confer risk. Until we identify the risk-driving variants, identifying the genes influenced by these variants, and therefore translating genetic information to improved clinical care, will remain an insurmountable task. We used a function-based approach for identifying causal variant candidates and the target genes on JIA risk haplotypes. METHODS: We used a massively parallel reporter assay (MPRA) in myeloid K562 cells to query the effects of 5,226 SNPs in non-coding regions on JIA risk haplotypes for their ability to alter gene expression when compared to the common allele. The assay relies on 180&#xa0;bp oligonucleotide reporters ("oligos") in which the allele of interest is flanked by its cognate genomic sequence. Barcodes were added randomly by PCR to each oligo to achieve&#x2009;>&#x2009;20 barcodes per oligo to provide a quantitative read-out of gene expression for each allele. Assays were performed in both unstimulated K562 cells and cells stimulated overnight with interferon gamma (IFNg). As proof of concept, we then used CRISPRi to demonstrate the feasibility of identifying the genes regulated by enhancers harboring expression-altering SNPs. RESULTS: We identified 553 expression-altering SNPs in unstimulated K562 cells and an additional 490 in cells stimulated with IFNg. We further filtered the SNPs to identify those plausibly situated within functional chromatin, using open chromatin and H3K27ac ChIPseq peaks in unstimulated cells and open chromatin plus H3K4me1 in stimulated cells. These procedures yielded 42 unique SNPs (total&#x2009;=&#x2009;84) for each set. Using CRISPRi, we demonstrated that enhancers harboring MPRA-screened variants in the TRAF1 and LNPEP/ERAP2 loci regulated multiple genes, suggesting complex influences of disease-driving variants. CONCLUSION: Using MPRA and CRISPRi, JIA risk haplotypes can be queried to identify plausible candidates for disease-driving variants. Once these candidate variants are identified, target genes can be identified using CRISPRi informed by the 3D chromatin structures that encompass the risk haplotypes.

Humans↗