| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Original Studies |
Department of Medicine, University of Birmingham at Birmingham Heartlands (A.H.B., S.C.L.G., P.M.D.) and Queen Elizabeth Hospitals (J.M.H., A.A., J.C.-S., J.D., A.D., M.C.S., A.H.B., J.A.F., S.C.L.G.); the Department of Statistics, University of Birmingham (R.L.H.), Birmingham, United Kingdom B9 5SS; Royal Bournemouth Hospital (M.A.), Bournemouth, United Kingdom; and Royal Devon and Exeter Hospitals (A.H., K.M.), Exeter, United Kingdom
Address all correspondence and requests for reprints to: Dr. S. C. L. Gough, Department of Medicine, University of Birmingham, Birmingham Heartlands Hospital, Bordesley Green East, Birmingham, United Kingdom B9 5SS. E-mail: s.c.gough{at}bham.ac.uk
| Abstract |
|---|
|
|
|---|
2 = 21.7;
corrected P < 0.00003). Increased transmission of
the G allele was seen from heterozygous parents to affected offspring
compared to unaffected offspring (
2 = 5.7;
P = 0.025). Circulating free T4
concentrations at diagnosis were significantly associated with
CTLA-4 genotype (F = 3.26; P =
0.04). These results support the hypothesis that CTLA-4 may play a role
in regulating self-tolerance by the immune system and in the
pathogenesis of autoimmune disorders such as Graves disease. | Introduction |
|---|
|
|
|---|
In the present study we have, therefore, used the two approaches of a large case-control study and the family-based TDT (10) in white UK Caucasian subjects with Graves disease to investigate the role of the A/G polymorphism at position 49 in exon 1 of the CTLA-4 gene, previously reported to be associated with disease (5, 6, 7, 8). We further examined the relationship between the CTLA-4 gene A/G polymorphism genotypes and the severity of hyperthyroidism at presentation of disease to determine whether there was a link between genotype and Graves disease phenotype.
| Materials and Methods |
|---|
|
|
|---|
Families were also recruited, with blood samples obtained from the index case with Graves disease, both parents, and any unaffected siblings. All unaffected siblings had tests of thyroid function and autoantibody status, and any showing evidence of subclinical autoimmune thyroid disease were removed from the study before genotyping. In total, DNA was obtained from 379 index cases with Graves disease and 364 control subjects for the population case-control association study and from 179 families for TDT analysis.
Patients attending the Queen Elizabeth Hospital thyroid clinic were subsequently analyzed for association between CTLA-4 genotype and severity of biochemical hyperthyroidism, determined by measurement of the serum concentration of free T4 at diagnosis, before initiation of antithyroid therapy. Additional clinical information was obtained from the thyroid register (11), including gender, age at diagnosis, smoking history, and the presence and size of diffuse goiter.
The study was approved by local ethics committees, and all subjects gave informed, written consent.
Genotyping of datasets
DNA was prepared from 10 mL whole blood, using the Nucleon Bacc II kit (Nucleon Biosciences, UK). Amplification of target DNA in exon 1 of the CTLA-4 gene was carried out using the PCR with primers 5'-GTC AAG GGA CCA TTA GAA G-3' and 5'-CTT TGC AGA AGA CAG GGA TGA A-3'. The reaction was performed in a final volume of 25 µL containing 200 ng genomic DNA, 1 µmol/L of each primer, 0.4 U Taq polymerase with appropriate buffer, 2.5 mmol/L magnesium chloride, and 200 µmol/L/L deoxy-NTPs. Amplification was performed in a MJ Research, Inc. Tetrad thermal cycler and consisted of 25 cycles of 94 C for 30 s, 55 C for 30 s, and 72 C for 30 s. The amplicon was 685 bp in length and was visualized on a 2% agarose gel stained with ethidium bromide. The described polymorphism in exon 1 results in an A-G change, giving rise to a BbvI restriction site. Restriction fragment length polymorphism analysis was performed on 5 µL PCR product, digested in a final volume of 10 µL under appropriate buffer conditions with 1 U BbvI enzyme at 37 C over 2 h. The resulting digestion products were then visualized on a 4% Nusieve-agarose (3:1) gel stained with ethidium bromide.
Statistical analysis
Analysis of the case-control data was performed using the
2 test with 95% confidence limits. Where appropriate,
P values were corrected for the number of comparisons made,
and P < 0.05 was considered significant. Odds ratios
were calculated by the method of Woolf with Haldanes modification for
small numbers (12). The TDT (10) was used to test for linkage in the
presence of linkage disequilibrium between the A/G polymorphism and
disease in the family dataset. In this analysis a significant excess of
transmission frequency of an allele from a heterozygous parent to an
affected offspring compared to that to an unaffected offspring is
evidence of linkage in the presence of linkage disequilibrium between
the associated allele and disease. The CTLA-4 gene A/G
polymorphism genotypes were also analyzed with respect to circulating
free T4 concentrations at diagnosis by ANOVA using the
Minitab version 12 statistical package (Minitab, Inc., State College,
PA). Log transformation of free T4 concentrations resulted
in a normal distribution of the residuals.
| Results |
|---|
|
|
|---|
Three hundred and seventy-nine patients with Graves disease and
364 control subjects were genotyped for the A/G polymorphism in exon 1
of the CTLA-4 gene. All Graves patients and 363 of 364
control subjects were successfully genotyped at this locus. The
distribution of the A and G alleles among Graves patients and control
subjects is summarized in Table 1
. A
highly significant increase in the frequency of the G allele was seen
in Graves patients compared with control subjects [42%
vs. 31.5%, respectively; corrected P value
(Pc) < 0.0002; odds ratio = 1.58]. The
distribution of genotypes AA, AG, and GG among Graves patients and
control subjects is summarized in Table 2
. The distribution of the genotypes
differed significantly between the two groups
(
2 = 21.7; Pc < 0.00003).
This difference reflected a significant decrease in the AA genotype in
Graves patients compared with control subjects (32.1% vs.
45.1%, respectively;
2 = 12.74;
Pc < 0.001) and an increase in the GG genotype among
Graves patients compared with control subjects (17.3% vs.
7.8%, respectively;
2 = 6.64;
Pc = 0.02).
|
|
Transmission of the G and A alleles from heterozygous parents to
affected and unaffected offspring was analyzed using the standard TDT.
Of the 179 families available for study, 96 were informative for
transmission of these alleles. A 2 x 2 test of heterogeneity
comparing transmission of the G and A alleles to affected and
unaffected offspring (Table 3
) confirmed that there
was a significant difference in transmission frequencies to affected
offspring compared with that to unaffected offspring
(
2 = 5.7; P = 0.025).
|
Serum free T4 concentrations at diagnosis were available for 247 patients with Graves disease. Serum free T4 concentrations showed significant variation with goiter size (F = 18.18; P < 0.0005) and smoking status (F = 5.39; P = 0.021) and were, therefore, included as variables in the model. There was a significant association between the serum free T4 concentration and the CTLA-4 genotype (F = 3.26; P = 0.04). Free T4 concentrations were highest in patients with the GG genotype [estimated mean, 62.5 pmol/L; 95% confidence interval (CI), 53.972.4], lowest in patients with the AA genotype (mean, 50.9 pmol/L; 95% CI, 45.956.4), and intermediate in the AG heterozygote state (mean, 54.0 pmol/L; 95% CI, 49.758.6).
| Discussion |
|---|
|
|
|---|
In our first dataset, analysis of findings from a large
population-based case-control study supports the previously reported
allelic association between the G allele of the CTLA-4 gene
and Graves disease (5, 6, 7, 8). The large numbers used in the present
study make the possibility of a false positive result due to a random
event highly unlikely (
2 = 16.6; Pc
= 0.0002). Although this method has the ability to detect allelic
association with a high degree of specificity, it lacks the sensitivity
to determine whether the differences observed between diseased and
control populations are due to allelic association between the marker
allele and the disease. It is not possible, for example, to exclude
population stratification as an alternative explanation of the results
(18). We, therefore, used the TDT in a second family-based dataset to
confirm that our findings were the result of linkage disequilibrium.
The TDT examined the frequency with which the G allele in exon 1 of the
CTLA-4 gene was transmitted from parents heterozygous for
this allele to offspring affected and unaffected by Graves disease.
We found a significant preferential transmission of the G allele to
affected offspring (57.9%) compared with that to unaffected offspring
(43.8%). This confirms allelic association of the G allele with
Graves disease found in the case-control study. The TDT analysis has,
therefore, allowed detection of the CTLA-4 gene as a
susceptibility locus in Graves disease families, which has previously
been undetected by classical linkage analysis (9). This form of
analysis is more powerful because the selection of informative
heterozygous parents overcomes the problem of high population
frequencies of disease alleles encountered in linkage studies. Although
linkage and linkage disequilibrium have been demonstrated between these
polymorphisms and type 1 diabetes in family-based studies (6, 19), this
is the first report in Graves disease.
The CTLA-4 molecule is a member of the same family of cell surface molecules as CD28 and, along with CD28, can bind to B7. The CTLA-4/B7 complex competes with the CD28/B7 complex and delivers negative signals to the T cell, thereby affecting T cell expansion, cytokine production, and immune responses (20). Although the CTLA-4 molecule may control peripheral T cell tolerance during the course of an immune response, it remains unknown how it may be contributing to the development of Graves disease. Antibody formation in Graves disease appears to be the result of T helper 2 cell action (21), with increases in interleukin-4 and interleukin-10 levels in patients with disease (22). A functional mutation of the CTLA-4 gene could, therefore, have a negative affect on the down-regulation of T cell function, with subsequent increases in autoantibody formation and the development of disease. We have presented evidence for a relationship between allelic variation of the CTLA-4 gene and circulating free T4 concentrations at the time of diagnosis of disease, which serves as a marker of the severity of disease. The greatest degree of biochemical dysfunction was seen in those subjects homozygous for the G allele. Although the G (alanine) polymorphism in exon 1 of the CTLA-4 gene has no known functional role, it is in linkage disequilibrium with the (AT)n microsatellite in the 3'-untranslated region and could, therefore, affect ribonucleic acid stability, down-regulation of T cell function, and subsequent development of disease. Equally, it may be in linkage disequilibrium with another, as yet unknown, disease-causing mutation.
Taken together, therefore, our findings not only show that the G allele of the A/G polymorphism is linked to Graves disease, but that the GG genotype is associated with more severe biochemical disease at presentation. These results support the hypothesis that CTLA-4 may play an important role in regulating self-tolerance by the immune system and hence in the pathogenesis of autoimmune disorders such as Graves disease. However, further genetic and functional immunological studies are needed to discover the true identity and mechanism of action of the etiological mutation at this locus.
|
| Acknowledgments |
|---|
| Footnotes |
|---|
2 Smith and Nephew Medical Research Fellow. ![]()
Received February 1, 1999.
Accepted March 17, 1999.
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
F. K. Kavvoura, T. Akamizu, T. Awata, Y. Ban, D. A. Chistiakov, I. Frydecka, A. Ghaderi, S. C. Gough, Y. Hiromatsu, R. Ploski, et al. Cytotoxic T-Lymphocyte Associated Antigen 4 Gene Polymorphisms and Autoimmune Thyroid Disease: A Meta-Analysis J. Clin. Endocrinol. Metab., August 1, 2007; 92(8): 3162 - 3170. [Abstract] [Full Text] [PDF] |
||||
![]() |
P.-W. Wang, I-Y. Chen, R.-T. Liu, C.-J. Hsieh, E. Hsi, and S.-H. H. Juo Cytotoxic T Lymphocyte-Associated Molecule-4 Gene Polymorphism and Hyperthyroid Graves' Disease Relapse after Antithyroid Drug Withdrawal: A Follow-Up Study J. Clin. Endocrinol. Metab., July 1, 2007; 92(7): 2513 - 2518. [Abstract] [Full Text] [PDF] |
||||
![]() |
D.S. C. Graham, A.K. Wong, N.J. McHugh, J.C. Whittaker, and T. J. Vyse Evidence for unique association signals in SLE at the CD28-CTLA4-ICOS locus in a family-based study Hum. Mol. Genet., November 1, 2006; 15(21): 3195 - 3205. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. C. Taylor, S. C. Gough, P. J. Hunt, T. H. Brix, K. Chatterjee, J. M. Connell, J. A. Franklyn, L. Hegedus, B. G. Robinson, W. M. Wiersinga, et al. A Genome-Wide Screen in 1119 Relative Pairs with Autoimmune Thyroid Disease J. Clin. Endocrinol. Metab., February 1, 2006; 91(2): 646 - 653. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. Atan, S. J. Turner, D. J. Kilmartin, J. V. Forrester, J. Bidwell, A. D. Dick, and A. J. Churchill Cytokine Gene Polymorphism in Sympathetic Ophthalmia Invest. Ophthalmol. Vis. Sci., November 1, 2005; 46(11): 4245 - 4250. [Abstract] [Full Text] [PDF] |
||||
![]() |
C E Jennings, C J Owen, V Wilson, and S H S Pearce A haplotype of the CYP27B1 promoter is associated with autoimmune Addison's disease but not with Graves' disease in a UK population J. Mol. Endocrinol., June 1, 2005; 34(3): 859 - 863. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y.-C. Weng, M.-J. Wu, and W.-S. Lin CT60 Single Nucleotide Polymorphism of the CTLA-4 Gene Is Associated with Susceptibility to Graves' Disease in the Taiwanese Population Ann. Clin. Lab. Sci., January 1, 2005; 35(3): 259 - 264. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. M. Anjos, M.-C. Tessier, and C. Polychronakos Association of the Cytotoxic T Lymphocyte-Associated Antigen 4 Gene with Type 1 Diabetes: Evidence for Independent Effects of Two Polymorphisms on the Same Haplotype Block J. Clin. Endocrinol. Metab., December 1, 2004; 89(12): 6257 - 6265. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Ban, E. S. Concepcion, R. Villanueva, D. A. Greenberg, T. F. Davies, and Y. Tomer Analysis of Immune Regulatory Genes in Familial and Sporadic Graves' Disease J. Clin. Endocrinol. Metab., September 1, 2004; 89(9): 4562 - 4568. [Abstract] [Full Text] [PDF] |
||||
![]() |
P.-W. Wang, R.-T. Liu, S.-H. H. Juo, S.-T. Wang, Y.-H. Hu, C.-J. Hsieh, M.-H. Chen, I-Y. Chen, and C.-L. Wu Cytotoxic T Lymphocyte-Associated Molecule-4 Polymorphism and Relapse of Graves' Hyperthyroidism after Antithyroid Withdrawal J. Clin. Endocrinol. Metab., January 1, 2004; 89(1): 169 - 173. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. S. Prabhakar, R. S. Bahn, and T. J. Smith Current Perspective on the Pathogenesis of Graves' Disease and Ophthalmopathy Endocr. Rev., December 1, 2003; 24(6): 802 - 835. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Tomer and T. F. Davies Searching for the Autoimmune Thyroid Disease Susceptibility Genes: From Gene Mapping to Gene Function Endocr. Rev., October 1, 2003; 24(5): 694 - 717. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Kretowski, N. Wawrusiewicz, K. Mironczuk, J. Mysliwiec, M. Kretowska, and I. Kinalska Intercellular Adhesion Molecule 1 Gene Polymorphisms in Graves' Disease J. Clin. Endocrinol. Metab., October 1, 2003; 88(10): 4945 - 4949. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. E. Collins, J. M. Heward, J. Carr-Smith, J. Daykin, J. A. Franklyn, and S. C. L. Gough Association of a Rare Thyroglobulin Gene Microsatellite Variant with Autoimmune Thyroid Disease J. Clin. Endocrinol. Metab., October 1, 2003; 88(10): 5039 - 5042. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Jin, W. Teng, S. Ben, X. Xiong, J. Zhang, S. Xu, Y. Y. Shugart, L. Jin, J. Chen, and W. Huang Genome-Wide Scan of Graves' Disease: Evidence for Linkage on Chromosome 5q31 in Chinese Han Pedigrees J. Clin. Endocrinol. Metab., April 1, 2003; 88(4): 1798 - 1803. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Vaidya, P. Kendall-Taylor, and S. H. S. Pearce The Genetics of Autoimmune Thyroid Disease J. Clin. Endocrinol. Metab., December 1, 2002; 87(12): 5385 - 5397. [Full Text] [PDF] |
||||
![]() |
S. Anjos, A. Nguyen, H. Ounissi-Benkalha, M.-C. Tessier, and C. Polychronakos A Common Autoimmunity Predisposing Signal Peptide Variant of the Cytotoxic T-lymphocyte Antigen 4 Results in Inefficient Glycosylation of the Susceptibility Allele J. Biol. Chem., November 22, 2002; 277(48): 46478 - 46486. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Collin, K. Kaukinen, M. Valimaki, and J. Salmi Endocrinological Disorders and Celiac Disease Endocr. Rev., August 1, 2002; 23(4): 464 - 483. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Kinjo, N. Takasu, I. Komiya, T. Tomoyose, M. Takara, T. Kouki, Y. Shimajiri, K. Yabiku, and H. Yoshimura Remission of Graves' Hyperthyroidism and A/G Polymorphism at Position 49 in Exon 1 of Cytotoxic T Lymphocyte-Associated Molecule-4 Gene J. Clin. Endocrinol. Metab., June 1, 2002; 87(6): 2593 - 2596. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Vaidya, S. H. S. Pearce, S. Charlton, N. Marshall, A. D. Rowan, I. D. Griffiths, P. Kendall-Taylor, T. E. Cawston, and S. Young-Min An association between the CTLA4 exon 1 polymorphism and early rheumatoid arthritis with autoimmune endocrinopathies Rheumatology, February 1, 2002; 41(2): 180 - 183. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. H. Kacem, N. Kaddour, F.-Z. Adyel, Z. Bahloul, and H. Ayadi HLA-DQB1 CAR1/CAR2, TNFa IR2/IR4 and CTLA-4 polymorphisms in Tunisian patients with rheumatoid arthritis and Sjogren's syndrome Rheumatology, December 1, 2001; 40(12): 1370 - 1374. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. F. Muller, H. A. Drexhage, and A. Berghout Postpartum Thyroiditis and Autoimmune Thyroiditis in Women of Childbearing Age: Recent Insights and Consequences for Antenatal and Postnatal Care Endocr. Rev., October 1, 2001; 22(5): 605 - 630. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. M. Holopainen and J. A. Partanen Technical Note: Linkage Disequilibrium and Disease-Associated CTLA4 Gene Polymorphisms J. Immunol., September 1, 2001; 167(5): 2457 - 2458. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Sakai, S. Shirasawa, N. Ishikawa, K. Ito, H. Tamai, K. Kuma, T. Akamizu, M. Tanimura, K. Furugaki, K. Yamamoto, et al. Identification of susceptibility loci for autoimmune thyroid disease to 5q31-q33 and Hashimoto's thyroiditis to 8q23-q24 by multipoint affected sib-pair linkage analysis in Japanese Hum. Mol. Genet., June 1, 2001; 10(13): 1379 - 1386. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Tomer, D. A. Greenberg, G. Barbesino, E. Concepcion, and T. F. Davies CTLA-4 and Not CD28 Is a Susceptibility Gene for Thyroid Autoantibody Production J. Clin. Endocrinol. Metab., April 1, 2001; 86(4): 1687 - 1693. [Abstract] [Full Text] |
||||
![]() |
M. K. Oaks and K. M. Hallett Cutting Edge: A Soluble Form of CTLA-4 in Patients with Autoimmune Thyroid Disease J. Immunol., May 15, 2000; 164(10): 5015 - 5018. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Nithiyananthan, J. M. Heward, A. Allahabadia, A. H. Barnett, J. A. Franklyn, and S. C. L. Gough A Heterozygous Deletion of the Autoimmune Regulator (AIRE1) Gene, Autoimmune Thyroid Disease, and Type 1 Diabetes: No Evidence for Association J. Clin. Endocrinol. Metab., March 1, 2000; 85(3): 1320 - 1322. [Abstract] [Full Text] |
||||
![]() |
Mapping the Major Susceptibility Loci for Familial Graves' and Hashimoto's Diseases: Evidence for Genetic Heterogeneity and Gene Interactions J. Clin. Endocrinol. Metab., December 1, 1999; 84(12): 4656 - 4664. [Abstract] [Full Text] |
||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Endocrinology | Endocrine Reviews | J. Clin. End. & Metab. |
| Molecular Endocrinology | Recent Prog. Horm. Res. |