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Biomedical subjects

C Darke

Publications and source records attributed to C Darke.

At least 91 records · Page 5Linked to original sources
PubMed1994

Gene frequency and linkage disequilibrium analysis of HLA-DRB1*04 haplotypes in a south Wales population.

HLA-DRB1*04 allele frequencies have been determined in 184 HLA-DR4-positive unrelated blood donors from the South Wales area, using group-specific polymerase chain reaction (PCR) amplification and hybridization with sequence-specific oligonucleotide probes, PCR amplification with sequence-specific primers, and PCR single-strand conformation polymorphism analysis. Eight of the fifteen known HLA-DR4 sequences were detected in this study. Linkage disequilibrium analysis of HLA-DRB1*04 and HLA-B, -DR and -DQ alleles revealed distinct haplotypic associations for all the major alleles detected in this population, including the novel linkage of HLA-B55 with DRB1*0407. These results are relevant to the role of HLA-DRB1*04 haplotypes in determining allogeneic histocompatibility and disease susceptibility.

Cell Line↗
PubMed1994

Serological identification of a new HLA-B7 variant antigen--HLA-B7QUI.

A new HLA-B antigen, HLA-B7Qui that appears to be a variant of HLA-B7 has been identified. This antigen, which is HLA-Bw6 associated, reacts with approximately two-thirds of cytotoxic antisera stimulated by HLA-B7 or B27 that lack a B27 or B7 component, respectively. All anti-B7 + 27 antisera (stimulated by either B7 or B27) react with B7Qui as do most B22-stimulated sera possessing a B7 component. However, sera stimulated by B60, with or without a B7 component, fail to react with B7Qui. Family studies show the B7Qui allele to be unique to the haplotype-HLA-A32 CW6 B7Qui Bf*S C4A*6 C4B*1 DR11 DQ7 (GLO2). Six Caucasoid subjects on the panel of 6861 HLA-typed potential bone marrow donors have this antigen (phenotype frequency, 0.08745%; gene frequency, 0.04473%). Work undertaken during the 11th International Histocompatibility Workshop (Reekers et al., 1992) showed that B7Qui has the same isoelectric point as HLA-B702 and HLA-B703 (Bpot) and that B7Qui is distinct from the HLA-B7 variants B703, B7SL, BDT, B7 x 40, BRI, and B41v.

Female↗
PubMed1994

Genomic analysis of the F subtypes of human complement factor B.

Factor B of human complement is encoded within the Major Histocompatibility Complex (MHC) and is polymorphic, with up to 30 alleles defined by electrophoretic mobility. One of the most common alleles, BF*F, is subdivided into the FA and FB subtypes, which differ at the gene level by non-synonymous base substitutions in the seventh codon. We have found at this position a new restriction site polymorphism, as a Bsl I site absent from the FB allele. Using this restriction polymorphism, we have developed a method for BF F subtype determination, based on amplification by polymerase chain reaction of the 5' end of the BF gene, and digestion with Bsl I. This new method has been applied to a panel of 29 selected BF F individuals. A single strand DNA conformation analysis of the same region of the gene allowed us to confirm the above DNA-based BF F subtyping. During this study, two BF*F1 alleles showed discrepancies between protein and DNA typing, which were confirmed by our sequencing data. These were identical, in the 5' region, to BF*S and BF*FB genes, respectively. In a comparison with two protein subtyping methods, identical results were found for only one third of the selected samples. The conflicting results may arise, in part, from previously undescribed molecular heterogeneity within BF F subtypes, or from the presence of a null allele. Our new method allows BF*F subtyping to be used with confidence in the definition of disease-associated MHC haplotypes.

Alleles↗
PubMed1993

MHC-extended haplotypes in families of patients with Graves' disease.

MHC-extended haplotypes were investigated in multiplex families of patients with hyperthyroid GD. Using a combination of both phenotypic (serology and protein electrophoresis) and genotypic (DNA-RFLP) markers, 159 MHC-extended haplotypes extending from HLA-A across the MHC class III (C2, Bf, C4A, and C4B) toward the HLA-DR/DQ complex were deduced from 217 (51 and 166 affected and unaffected) members of 21 families of patients with GD. Thyroid autoantibodies were measured and found positive in 27.1% of 166 clinically euthyroid unaffected members. Extended haplotypes were classified into four categories--affected (n = 40), Aff/Ab + ve (shared haplotype between affected and Ab + ve members, n = 31), Ab + ve (n = 29), and Ab - ve (n = 59)--based on the presence and absence of these haplotypes in 51 affected members with GD and 45 and 121 unaffected members who were respectively positive and negative for thyroid autoantibodies. Five recombinations were detected: three were found between HLA-A and B and two between HLA-B and the MHC class III. No recombination was found between or within the MHC class III and class II complex. Though the HLA-DR17 (DR beta 17(1) and DR beta 17(2)) allele was found to be significantly increased in both the affected and the Aff/Ab + ve when compared with the Ab - ve haplotypes (p < 0.042 and p < 0.018), the frequency of the HLA-B8, 2.7-kb SstI-4.5-kb TaqI/C2 Bf*S, 6.4-kb TaqI/C4A*Q0C4B*1, HLA-DR beta 17(1)/DQ alpha 2-DQ beta 2a extended haplotype was found to be significantly increased only in the affected haplotype (p < 0.05). These results suggest that while HLA-DR17 is a susceptibility allele shared between GD and individuals with positive thyroid autoantibodies, the HLA-B8, 2.7-kb SstI-4.5-kb TaqI/5'-3'C2 Bf*S, 6.4-kb TaqI/C4A*Q0B*1, DR beta 17(1)/DQ alpha 2-DQ beta 2a is a disease susceptibility-extended haplotype for Graves' disease.

Adult↗
PubMed1993

Allelic typing of the HLA-DR4 group by polymerase chain reaction--single-strand conformation polymorphism analysis.

The technique of SSCP was applied to the molecular subtyping of the HLA-DR4 group of alleles. SSCPs were defined in 16 cell line DNAs, representing the alleles DRB1*0401-*0411 (except DRB1*0409), using group-specific PCR amplification, nondenaturing polyacrylamide gel electrophoresis, and silver staining. Three sets of gel electrophoresis conditions were necessary to differentiate the 10 alleles tested. The SSCPs defined in the cell line DNAs were validated by analysis of 145 unrelated HLA-DR4-positive individuals previously genotyped for DRB1*04 alleles by sequence-specific oligotyping. This study demonstrates the suitability of the SSCP technique for defining DRB1*04 alleles, particularly when a small number of samples require typing.

Alleles↗
PubMed1993

Serum ferritin, blood donation, iron stores and haemochromatosis.

Serum iron and ferritin concentrations were measured in 1,532 regular blood donors from South Wales who were undergoing HLA typing prior to registration on the British Bone Marrow and Platelet Donor Panel. Serum transferrin concentrations were determined for donors with serum iron concentrations > 24 mumol/l. There were 25 donors with transferrin saturations > 50% and 11 with transferrin saturations > 60%. There were five donors with serum ferritin concentrations > 200 micrograms/l (women) or > 300 micrograms/l (men). Two of the male donors had transferrin saturations > 50% and serum ferritin > 300 micrograms/l on repeat blood samples and are being treated by venesection. Donors with HLA-A3 did not differ from those without A3 in serum iron or ferritin concentrations. Even in the group of donors who were apparently homozygous for A3 there were neither abnormal serum iron nor ferritin concentrations. Although it is well established that measurements of transferrin saturation are required to detect homozygous haemochromatosis (HFE) in its earlier stages, the number of 'false-positive' results is likely to be unacceptably high for screening blood donors. Serum ferritin assays should identify donors with HFE and iron overload before the onset of liver damage. With two million regular donors and 300,000 new donors each year, a significant proportion of the U.K. population will be screened within 10 years. The assay of serum ferritin identifies donors with low levels of storage iron who are at risk of developing iron-deficiency anaemia. Furthermore, donation frequency may be increased for those donors with higher ferritin concentrations when blood supplies are low.

Adolescent↗
PubMed1992

Frequency of HLA-DPB1 alleles, including a novel DPB1 sequence, in the Northern Ireland population.

HLA-DPB1 allele frequencies in 150 unrelated normal individuals from Northern Ireland were determined using oligonucleotide typing methods. HLA-DPB1*0401 was the most common allele in the population possessed by 75.3% of subjects, followed by DPB1*0201 (20.7%). In addition to these alleles, only HLA-DPB1*0402, -DPB1*0301, and -DPB1*0501 were present in subjects at frequencies greater than 10%. The results in this study are in broad agreement with other Caucasoid studies, but there is regional and ethnic variation in HLA-DP allele frequencies. Three DPB1 alleles were found to be in linkage disequilibrium with HLA-DR antigens determined by RFLP, namely, DPB1*0101 with DRw17 (Dw24 associated) RFLP, DPB1*0501 with DRw13-Dw19 RFLP, and DPB1*1901 with DRw13-Dw18 (Dw25 associated) RFLP. One individual revealed a novel DPB1 pattern of probe reactivity, which following DNA sequencing was found to be HLA-DPB1*2001. To assess the system used and to compare consistency of results between laboratories, 62 cell lines were oligotyped for HLA-DP. The results revealed the system described here to be extremely accurate and showed excellent agreement of HLA-DP typing results for cell lines between laboratories.

Alleles↗
PubMed1990

DQA2 U allele: a genetic marker for relapse of Graves' disease.

The association of HLA-DR3 with Graves' disease in Caucasoids is well established but its significance is unclear and its clinical value as a predictive parameter for relapse after a course of antithyroid drug therapy is controversial. We have further investigated the predictive value at the genomic level in 51 patients with Graves' disease who were treated with a 6-month course of carbimazole and followed up for 2 years. Using DNA-restriction fragment length polymorphism (DNA-RFLP) allogenotyping, (i) complete concordance of HLA-DR assignment was observed between serological and DNA-RFLP analysis of all but one of 51 patients with Graves' disease; (ii) the DR beta 17(1)-DQ alpha 2-DQ beta 2a (a DNA-RFLP allogenotype of the classical Northern European haplotype of HLA-B8 DR3) was significantly (corrected P = Pcorr less than 0.02) associated with Graves' disease particularly in patients who relapsed (Pcorr less than 0.005); (iii) HLA-DR3 was highly associated with DQA2 U allele (chi 2 = 18.53, d.f.2, P less than 0.0005); (iv) a strong correlation between the DQA2 U allele and the outcome of the disease was observed. Relapse occurred in 91% (10/11) of the patients who were homozygous for the DQA2 U allele whilst only 65% (15/23) and 41% (7/17) of patients who were hetero or homo-zygous for the DQA2 L allele (DQA2 U/L and DQA2 L/L) relapsed within the same period of follow-up (chi 2 = 7.18, d.f.2, P less than 0.05). Though the relapse rate in patients with the DQA2 U/U genotype was not significantly higher than the relapse rate in patients with the DQA2 U/L genotype, it was significantly higher than the relapse rate in patients with DQA2 L/L genotype (P less than 0.0001) with a relative risk of 14.3.

Alleles↗
PubMed1990

A long-term follow-up of postpartum thyroiditis.

To investigate the long-term outcome of postpartum thyroiditis (PPT), 43 patients with PPT and 171 control women were evaluated 3.5 (range 2-4) years postpartum. Ten (23%) PPT patients were hypothyroid compared to none of the controls (P less than 0.001). Factors associated with the development of hypothyroidism were high antimicrosomal antibody titre measured at 16 weeks gestation (P less than 0.01), severity of hypothyroid phase of PPT, multiparity, and a previous history of spontaneous abortion. The presence of microsomal antibody but no PPT in one pregnancy did not prevent the occurrence of PPT in the next pregnancy in two patients and a further five patients had PPT in two successive pregnancies. There was no association between HLA haplotype, family history of thyroid disease, smoking or frequency of oral contraception, and the development of long-term hypothyroidism after PPT. It is concluded that permanent hypothyroidism is an important sequel to PPT and patients with PPT should be followed up appropriately.

Adult↗
PubMed1990

Postpartum thyroid dysfunction and HLA status.

Nine-hundred-and-one women presenting in an antenatal clinic at the 60th week of pregnancy were tested for antithyroid antibodies. A group of 113 antibody-positive women and 108 antibody-negative age-matched controls were HLA typed and followed prospectively at 6-weekly intervals through pregnancy and for 12 months postpartum. Forty-five of the women developed biochemical evidence of postpartum thyroid dysfunction (PPTD) of whom 36 were antibody positive. Compared with a local control population (n = 600), and using multiplex analysis, there was a significant increase in the combinations HLA B8, DR3 and HLA A1, B8, DR3 from 22.5% to 40.0% (P less than 0.02) and from 18.6% to 35.6% (P less than 0.01) respectively in the women who developed PPTD. The well-recognized association of these haplotypes with other organ-specific autoimmune diseases provides further support for autoimmune events being implicated in the development of PPTD.

Autoantibodies↗
PubMed1990

Severe intravascular haemolysis in a renal transplant recipient due to anti-B of donor origin.

A group B recipient of a group 0 kidney developed severe intravascular haemolysis due to the formation of anti-B. Immunoglobulin allotyping of donor serum, recipient serum and 'unexpected' anti-B antibody showed the antibody to be of donor origin. The patient and donor genotypes were Gm 3;5/3;5 and Gm 1,2;21/1;21, respectively, and the anti-B antibody allotype was Gm 1;21. The group B recipient of the other donor kidney showed no evidence of haemolysis. Possible factors influencing the occurrence and severity of post-transplantation haemolysis are discussed. The production of anti-A or anti-B antibodies in non-group 0 patients who receive group 0 organ transplants is well described [1-8]. We report a case of severe intravascular haemolysis in a group B patient who received a group 0 kidney, together with immunoglobulin allotyping studies which show conclusively that the antibody responsible for the haemolysis was of donor origin.

ABO Blood-Group System↗
PubMed1990

Spontaneous lymphocyte proliferation in severe periodontal disease: role of T and B cells.

Spontaneous proliferation of T cells, B cells and unseparated lymphocytes was studied in patients with severe periodontal disease and control subjects. In the patient group only, spontaneous lymphocyte proliferation was reduced, whereas B cell proliferation was enhanced. The findings offer further support for the existence of a disturbance in immune regulation in patients with severe periodontal disease.

Adult↗
PubMed1990

Primary standardization for the ELISA of serum thyroperoxidase and thyroglobulin antibodies and their prevalence in a normal Welsh population.

This paper describes the use of ELISA techniques, together with university available primary standards, for the assay of the thyroid autoantibodies anti-thyroperoxidase (TPOAb) and anti-thyroglobulin (TgAb). The data obtained using ELISA compared well with that obtained by passive haemagglutination giving correlation coefficients of 0.79 and 0.83 respectively. TPOAb and TgAb concentrations were assayed in serum samples from 832 healthy individuals aged between 18 and 45 years and cut-off values for both antibodies have been defined (TPOAb less than 19.6kIU/l; TgAb less than 98kIU/l). Applying these cut-off values, some 10% of the population showed elevated anti-thyroid antibody activity and, when divided by sex, a majority of this group belonged to the female population.

Adolescent↗
PubMed1989

A miniaturised method for immunoglobulin allotype serology.

A modification of the classic haemagglutination inhibition method for immunoglobulin allotyping is described which employs reagent volumes of 2 microliters compared with the 25 microliter volumes commonly used in other serological allotyping methods. No loss of sensitivity or specificity was associated with the miniaturised method when compared to the standard tile technique. This method simplifies the large scale phenotyping and screening of sera and permits considerable savings of valuable reagents to be made.

Gene Frequency↗