Factor B alleles and multiple sclerosis.
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Biomedical subjects
Publications and source records attributed to J Bertrams.
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A 16-month-old girl presented with an episode of fever and acute thrombocytopenic purpura caused by a Coxsackie B5 virus. On days 13 to 23, laboratory evidence of diabetes mellitus was present, followed by a 2 1/2-month remission, then by definitive insulin-dependent diabetes. The involvement of virologic, immunologic, and genetic factors in the pathophysiology was substantiated by the following data: (1) Virus-induced glucose intolerance was produced in selected mouse strains. (2) Islet-cell antibodies were found one week before onset of diabetes; however, circulating lymphocytes of the child at that time suppressed insulin release from islets in vitro. (3) Immunogenetic analysis of the child revealed the presence of high-risk genetic markers. It is suggested that the convergence of an insulotropic variant virus, genetic predisposition, and perhaps some uncontrolled adjuvant factors, e.g. steroid therapy and DPT vaccination, may have determined insular damage and anti-islet autoimmune reactions, leading to insulin-dependent diabetes mellitus.
HLA antigens A, B, C, DR and BF were determined in 14 sibling pairs with type I diabetes and in 61 patients without familial risks. Significantly positive associations of the disease with HLA DR3 and DR4 and a negative association with DR2 were found. Positive and negative associations with the various HLA A, B and C antigens (A1, A2, B8, B15, B18, Cw3) are of a secondary nature due to strong genetic coupling with primarily associated DR alleles. Localisation of diabetes-associated genes in the HLA DR region could be demonstrated in two families with HLA recombinations. In both cases the hypothetic disease gene segregated with the HLA DR segment. Joint evaluation of these data in an international series involving 1200 type I diabetics showed furthermore that around 90% of all patients are DR3 and/or DR4 positive, that the highest morbidity risk exists in DR3/4 heterozygosity and that DR4 positive persons usually fall ill before their 20th year of life and frequently in the last 3 months of the year. Allotment of clinical, epidemiological, virological and immunological criteria of type I diabetes to only one of the both risk factors indicates heterogeneous immunopathogenesis of the disease. HLA DR3 predisposes particularly to endocrine autoimmune disease and DR4 to increased virus susceptibility.
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In this review article, recent evidence is presented that some diseases like insulin-dependent diabetes mellitus, multiple sclerosis, and idiopathic membranous nephropathy, which are primarily associated with HLA-D,DR, are also related to the rare C2, C4, and Factor B alleles. Circumstantial evidence is available that at least some of these rare variants may be functionally deficient. Based on the concept of functionally interacting gene clusters, mutant complement genes may lead to impaired effector mechanisms in virus neutralization or lysis of virus-infected cells. Other mechanisms such as alteration of vascular permeability may be involved in the development of proliferative retinopathy and familial hypertension. In lepromatous lepra, an impaired cell-mediated lysis of M. leprae may be related to the hemolytically inactive C4F1 allelic product.
The authors report the case of a 12-year-old boy with hyperosmolar nonketotic diabetic coma. Pathogenetic aspects and the HLA genotype are discussed. To reduce the hyperglycaemia, a continuous intravenous infusion of regular insulin at a low rate was used. The too rapidly infused sodium-bicarbonate overloaded tha body with sodium and caused intracellular sodium accumulation with edema. This could explain the disorientation after regaining consciousness. Much more important than the sodium-bicarbonate infusion is an accurate rehydration regimen.
Five hundred and ninety-nine patients with insulin-dependent (Type 1) diabetes mellitus were typed for Bf (factor B) polymorphism, and 318 of them for HLA-A, B and C antigens. Bf and HLA antigen frequencies were compared with those in 536 normal controls. A significant positive association between Type 1 diabetes and the rare factor B variant BfF1 was found (p less than 10(-3)), but this was present only in patients aged under 16 years at onset of the disease (p less than 0.005). There was a strongly positive linkage disequilibrium between BfF1 and HLA-B18 in the diabetic patients. This, too was especially pronounced in the juvenile onset cases, in whom it was significantly stronger than in controls (p less than 10(-3)). The known positive associations between Type 1 diabetes and HLA-B8, -B15 and -Cw3 were confirmed.
Bf allotypes were determined in 200 multiple sclerosis (MS) patients and compared to analogous control frequencies. No significant deviation of any Bf phenotype was found. Also in HLA-B7- as well as Dw2-positive patients normal Bf frequencies existed.
A twin case of disputed paternity with probable superfetation is reported. The putative father could be excluded as the father of Twin F by HLA, GLO, and Ss typing results, but could not be excluded as the father of Twin S, with a probability of paternity for this twin of 99.995%. A birth weight difference of 450 g and the evidence for additional sexual intercourses by the mother suggest the very rare event of a superfetation.
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Altogether 1,072 HLA-A, B, Bf haplotypes in 536 parents of 268 German families were analyzed by gene and haplotype counting in order to investigate the two and three point association of HLA-A and B antigens with Bf alleles. In agreement with previously published data (Albert et al. 1975, Bender et al. 1977) significant positive linkage disequilibria were found for HLA-A3 and BfF, B7 and BfS, B8 and BfS, Bw35 and BfF, whereas significant negative Delta values appeared to exist for HLA-A3 and BfS, B7 and BfF, B8 and BfF, B12 and BfS, as well as Bw35 and BfS. Significant positive three point Delta values were found for the following haplotypes: HLA-A11, Bw35, BfS, HLA-Aw23, Bw35, BfS, HLA-A28, B12, BfS, HLA-A2, B17, BF, HLA-A3, Bw35, BfF, HLA-Aw24, b12, BfF and HLA-A29, B12, BfF. According to the large number of comparisons performed calculating the level of significance of the three point associations, these data have to be corroborated by further investigation. The three point Delta values, obtained by calculation from the patients' phenotypes differed markedly from those results obtained by haplotype counting.
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In the HLA complex it is evident that some antigens occur rather frequently, while others are rare. A statistically significant increase or decrease of any of these antigens in a given number of patients suffering from the same disease therefore suggests an association between such a disease and the HLA-system. In this study the Author compared the HLA antigen frequencies of 1.000 M.S. patients and 1.000 healthy controls, tissue typed during the same time period by the identical antiserum-set.
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