ABSTRACT
Single-nucleotide polymorphisms (SNPs) within the tumour necrosis factor alpha (TNF-alpha) gene on chromosome 6p21.3 have been associated with many autoimmune diseases; however, results have been conflicting and accurate allele frequencies have never been established in a UK Caucasian population. The aim of this study was to assess the frequency of 22 known TNF-alpha SNPs in a UK Caucasian control population and investigate association of all polymorphisms with >5% minor allele frequency in a large case-control data set of patients with Graves' disease (GD). Eight of the 22 SNPs had minor allele frequencies >5% and were investigated further. The other 14 SNPs were present in the UK population at frequencies ranging from 0 to 4.7%. A significant increase of the A allele of the -238 SNP was seen in GD patients when compared with control subjects (9.6 vs 6.8%, respectively; P=0.003) and mirrored in the genotype distribution (P=0.009). Furthermore, association of the -238 SNP appears not to be due to linkage disequilibrium of the known HLA-DRB1(*)03 associations with GD. This study has established accurate allele frequencies of TNF-alpha SNPs in a UK population and provides preliminary evidence for association of the TNF-alpha gene with GD.
Subject(s)
Graves Disease/genetics , Polymorphism, Genetic , Tumor Necrosis Factor-alpha/genetics , Case-Control Studies , Gene Frequency , Genotype , Humans , Linkage Disequilibrium , Polymorphism, Single Nucleotide , Sequence Analysis, DNAABSTRACT
OBJECTIVE: Vitamin D modulates the immune system by suppressing the proliferation of activated T cells, with its actions being directed through the vitamin D receptor (VDR). A number of single nucleotide polymorphisms (SNPs) have been identified in the VDR gene, of which several have been associated with autoimmune diseases, including type 1 diabetes and Graves' disease (GD) in Japanese females. The aim of this study was to test for association of polymorphisms of the VDR gene in the genetic susceptibility to GD in UK Caucasians. DESIGN: Target DNA for five previously published SNPs, four novel SNPs and one microsatellite marker was amplified by the polymerase chain reaction (PCR). Subsequent genotyping was performed using restriction fragment length polymorphism (RFLP) or microsatellite genotyping analysis, according to the type of VDR polymorphism. PATIENTS: We obtained DNA from a case-control dataset consisting of 768 patients with GD and 864 control subjects. All patients and control subjects were Caucasians born in the UK, and all gave informed, written consent. MEASUREMENTS: Frequencies of the alleles and genotypes of the ten VDR gene polymorphisms were compared between patients and control subjects using the chi2 test. Odds ratios were calculated using Woolf's method with Haldane's modification for small numbers and D prime (D') was calculated to assess the level of linkage disequilibrium (LD) between the ten polymorphisms. RESULTS: No differences in allele or genotype frequencies were observed between GD cases and control subjects for any of the nine SNPs studied. The S allele of the PolyA microsatellite marker was slightly more frequent in GD cases when compared with control subjects (chi2= 4.364, P = 0.04). Strongest LD between markers was observed towards the 3' end of the VDR gene but there was no evidence of association with disease. CONCLUSION: This is the largest and most comprehensive study of the VDR gene in GD to date and these data suggest that these polymorphisms of the VDR gene do not contribute to GD susceptibility in the UK.
Subject(s)
Graves Disease/genetics , Polymorphism, Single Nucleotide/genetics , Receptors, Calcitriol/genetics , White People , Case-Control Studies , Chi-Square Distribution , Genetic Predisposition to Disease , Graves Disease/ethnology , Humans , Linkage Disequilibrium , Microsatellite Repeats , Polymerase Chain Reaction/methods , Polymorphism, Restriction Fragment Length , United KingdomABSTRACT
Up to half of patients with Graves' hyperthyroidism have signs of thyroid associated ophthalmopathy, but the factors that cause this disorder are unknown. We investigated two major genetic susceptibility loci for Graves' disease in ophthalmopathy; the MHC class II region and the cytotoxic T lymphocyte antigen-4 (CTLA4) gene. Allelic frequencies of these genes in patients with Graves' disease who did and did not have concurrent thyroid-associated ophthalmopathy did not differ, and are, therefore, unlikely to contribute to its development.
Subject(s)
Antigens, Differentiation/genetics , Genes, MHC Class II/genetics , Graves Disease/genetics , Immunoconjugates , Abatacept , Adult , Alleles , Antigens, CD , CTLA-4 Antigen , Case-Control Studies , Female , Genetic Predisposition to Disease , Genotype , Graves Disease/etiology , Humans , Logistic Models , Male , Smoking/adverse effectsABSTRACT
Graves' disease (GD) is an autoimmune thyroid disease of unknown etiology, although predisposition to the development of this disease is thought to be caused by both genetic and environmental factors. Recently, an association between a promoter polymorphism of the interleukin 4 gene and GD has been reported. A C-T base change at position -590 showed modest protection against the development of GD in a United Kingdom data set of 135 patients with GD and 101 controls. This polymorphism was, therefore, investigated in a much larger case-control cohort of 384 patients with GD and 288 control subjects using PCR, followed by restriction fragment length polymorphism analysis. No protective effect of the T allele of this polymorphism was observed in our data set, and indeed no significant difference in either allelic or genotypic distribution was seen between the patient and control groups. Moreover, calculation of probabilities indicate that the original study lacked sufficient power to support the conclusions drawn. Our data support the hypothesis that the C-T promoter polymorphism of the interleukin 4 gene does not confer protection against the development of GD in Caucasians in the United Kingdom.
Subject(s)
Graves Disease/genetics , Interleukin-4/genetics , Polymorphism, Genetic , Polymorphism, Restriction Fragment Length , Promoter Regions, Genetic , White People/genetics , Alleles , Case-Control Studies , Chromosome Mapping , Chromosomes, Human, Pair 18 , Cohort Studies , DNA/blood , Gene Frequency , Genotype , Graves Disease/immunology , Humans , Point Mutation , Polymerase Chain Reaction , Reference Values , United KingdomABSTRACT
Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare monogenic autoimmune disease with endocrine components including type 1 diabetes, adrenal failure, and thyroid dysfunction, with major autoantibodies directed against adrenal, pancreas, and thyroid tissue. A 13-bp deletion in exon 8 of the autoimmune regulator (AIRE1) gene on chromosome 21q22.3 accounts for more than 70% of mutant alleles in United Kingdom subjects with APECED. To determine whether this polymorphism contributes to disease susceptibility in subjects with autoimmune disease in general, we screened 302 patients with Graves' disease, 154 patients with autoimmune hypothyroidism, 235 patients with type 1 diabetes, and 318 control subjects for the 13-bp deletion of the AIRE1 gene. The mutation was present in only 1 (0.33%) patient with Graves' disease, 1 patient with autoimmune hypothyroidism (0.6%), and 1 (0.315) of the control subjects. No patients with type 1 diabetes were found to carry the mutation. We conclude, therefore, that the 13-bp deletion of the AIRE1 gene is not a susceptibility locus for the more common autoimmune endocrinopathies in the United Kingdom.
