- Email: [email protected]
Polymorphisms in the protein tyrosine phosphatase (PTPN22) gene is not associated with autoimmune thyroid in a large affected Tunisian family
LETTERS TO THE EDITOR
235
[2] K. Wing, S. Lindgren, G. Kollberg, A. Lundgren, R.A. Harris, A. Rudin, S. Lundin, E. Suri-Payer, CD4 T cell activation by myelin oligodendrocyte glycoprotein is suppressed by adult but not cord blood CD25+ T cells, Eur. J. Immunol. 33 (2003) 579 – 587. [3] S. Lindley, C.M. Dayan, A. Bishop, B.O. Roep, M. Peakman, T.I. Tree, Defective suppressor function in CD4+CD25+ T-cells from patients with type 1 diabetes, Diabetes 54 (2005) 92 – 99. [4] R. Khattri, T. Cox, S.A. Yasayko, F. Ramsdell, An essential role for Scurfin in CD4+CD25+ T regulatory cells, Nat. Immunol. 4 (2003) 337 – 342. [5] S. Hori, T. Nomura, S. Sakaguchi, Control of regulatory T cell development by the transcription factor Foxp3, Science 299 (2003) 1057 – 1061.
Clare Baecher-Allan Center for Neurologic Disease, Brigham and Women s Hospital, 77 Avenue Louis Pasteur, Boston, MA 02115, USA E-mail address: [email protected]. 25 March 2006 doi:10.1016/j.clim.2006.03.013
Polymorphisms in the protein tyrosine phosphatase (PTPN22) gene is not associated with autoimmune thyroid in a large affected Tunisian family The pathogenesis of autoimmune thyroid diseases (AITDs) involves a complex interaction between genetic and environmental factors [1]. Several candidate genes have been examined for a possible contribution to genetic susceptibility to the AITDs by means of both association and linkage analyses [2]. An attractive candidate for additional susceptibility is PTPN22 (protein tyrosine phosphatase N22) that encodes a lymphoid-specific phosphatase known as Lyp and plays a key role as a negative regulator of T-cell activation by dephosphorylating T-cell receptor activation-dependent kinases. An additional function of Lyp is to downregulate activation of T-cells by binding to C-terminal Src tyrosine kinase (Csk), which is an important suppressor of kinases that mediate Tcell activation [3]. PTPN22 gene located on chromosome 1q13.3—13.1 harbors one functional SNP (rs 2476601) that leads to a change at codon 620 from arginine to a tryptophan (R620W). The minor allele of the R620W missense SNP has been associated with several autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, Hashimoto’s thyroiditis and type 1 diabetes [4]. Given the shared genetic susceptibility among autoimmune diseases and the association of PTPN22 gene, we investigated the PTPN22 polymorphism in a large Tunisian family (Akr family) composed of ten generations of more than 400 members, including 76 patients subdivided into 40 patients affected with GD, 13 patients with HT and 23 patients with Atrophic thyroiditis (PIM). The female/male ratio is 1 in GD patients, 3.3 in HT patients and 4.2 for
patients with PIM. Patients’ age at the onset of AITDs in this isolate ranged from 7 to 70 years (median age of 35 years). Fifty-six patients carried at least one HLA-DR11 susceptibility allele [5]. The dimorphism (C/T) was defined by PCR-RFLP method using XcmI enzyme. Two fragments of 173 and 42 bp were obtained after digestion when the PCR product containing the T allele. Statistical analysis was performed by family-based association test (FBAT) using empirical variance (the e option) [6]. We calculated FBAT scores under different models (recessive, additive and dominant) using 45 nuclear families with 167 individuals (extracted automatically by FBAT from Akr family). The FBAT analysis showed no significant association with R620W under the three models ( P = 0.19 for all models). Stratifying patients according to their phenotype (GD, HT and PIM) did not show any significant association with PTPN22 R620W allele ( P N 0.05). To establish whether PTPN22 association with AITDs was dependent on the presence of HLA-DR allele, the frequency of PTPN22 alleles was analyzed in the subgroup of patients who carried at least one HLA-DR11 allele. Our results failed to detect any evidence of interaction between PTPN22 C1858T dimorphism and HLA-DR11 ( P = 0.052). Based on these results, we conclude that C1858T polymorphisms of PTPN22 are unlikely to be associated with AITDs in the Akr family. Our results are in agreement with those reported by Ban et al. [7] on 334 unrelated Japanese patients with AITDs and 179 controls that showed negative association of C1858T polymorphisms with susceptibility to AITDs and our previous results indicating an absence of association between PTPN22 (C/T) dimorphism and RA in Tunisian case—control study ( P = 0.24) (unpublished results). Similar negative results have been reported for multiple sclerosis, Crohn disease and primary Sjo ¨gren’s syndrome [8—10]. This discrepancy of the associated allele may reflect genetic heterogeneity in the genetic basis of susceptibility to AITDs. In conclusion, the C1858T variant of PTPN22 does not appear to play a major role in AITDs pathogenesis in our data set. Analyses of the role of this SNP in additional autoimmune disorders should provide hints about the underlying mechanisms of these complex diseases as well as a framework to begin to understand how they are related and why some autoimmune diseases can cosegregate in the same families.
Acknowledgments Funding: AFP, ARP, Association Franc¸aise des Polyarthritiques, Association de Recherche pour la Polyarthrite, Association Polyarctique, SFR, Genopole (France), Ministe `re de l’Enseignement Supe ´rieur, Ministe `re la Recherche Scientifique et de la Technologie (Tunisie) and The International Centre for Genetic Engineering and Biotechnology (ICGEB) Trieste (Italy).
References [1] Y. Tomer, T.F. Daves, Infection thyroid disease and autoimmunity, Endocr. Rev. 14 (1993) 107 – 120. [2] H. Ayadi, H. Hadj Kacem, A. Rebai, N.R. Farid, The genetics of autoimmune thyroid disease, Trends Endocrinol. Metab. 15 (2004) 234 – 239.
236 [3] S. Cohen, H. Dadi, E. Shaoul, N. Sharfe, C.M. Roifman, Cloning and characterization of a lymphoid specific inducible human protein tyrosine phosphatase Lyp, Blood 93 (1999) 2013 – 2024. [4] L.A. Criswell, K.A. Pfeiffer, R.F. Lum, B. Gonzales, J. Novitzke, M. Kern, K.L. Moser, A.B. Begovich, V.E. Carlton, W. Li, A.T. Lee, W. Ortmann, T.W. Behrens, P.K. Gregersen, Analysis of families in the multiple autoimmune disease genetics consortium (MADGC) collection: the PTPN22 620W allele associates with multiple autoimmune phenotypes, Am. J. Hum. Genet. 76 (2005) 561 – 571. [5] N. Elleuch-Bougacha, A. Maalej, H. Makni, M. Bellassouad, M. Abid, J. Jouida, K. Ayed, D. Charron, R. Tamouza, H. Ayadi, HLA class I and II polymorphisms in a large multiplex family with autoimmune thyroid diseases, Clin. Endocrinol. (Oxford) 55 (2001) 163 – 557. [6] D. Rabinowitz, M.N. Laird, A unified approach to adjusting association tests for population admixture with arbitrary pedigree structure and arbitrary missing marker information, Hum. Hered. 50 (2000) 211 – 223. [7] Y. Ban, T. Tozaki, M. Taniyama, M. Tomita, Y. Ban, The codon 620 single nucleotide polymorphism of the protein tyrosine phosphatase 22 gene does not contribute to autoimmune thyroid disease susceptibility in the Japanese, Thyroid 15 (2005) 1115 – 1118. [8] A.B. Begovich, S.J. Caillier, H.C. Alexander, J.M. Penko, S.L. Hauser, L.F. Barcellos, J.R. Oksenberg, The R620W polymorphism of the protein tyrosine phosphatase PTPN22 is not associated with multiple sclerosis, Am. J. Hum. Genet. 76 (2005) 184 – 187. [9] S.E. Wagenleiter, W. Klein, T. Griga, W. Schmiegel, J.T. Epplen, P. Jagiello, A case—control study of tyrosine phosphatase (PTPN22) confirms the lack of association with Crohn’s disease, Int. J. Immunogenet. 32 (2005) 323 – 324. [10] M. Ittah, J.E. Gottenberg, A. Proust, A. Hachulla, X. Puechal, P. Loiseau, X. Mariette, C. Miceli-Richard, No evidence for association between 1858 C/T single-nucleotide polymorphism of PTPN22 gene and primary Sjogren’s syndrome, Genes. Immun. 6 (2005) 457 – 458.
LETTERS TO THE EDITOR G. Chabchoub A. Maalej H. Ayadi* Laboratoire de Ge ´ne´tique Mole´culaire Humaine, Faculte´ de Me ´decine, Avenue Majida Boulila 3029 de Sfax, Tunisie E-mail address: [email protected]. *Corresponding author. Fax: +216 74 461 403. E. Petit-Teixeira E. Glikmans F. Cornelis Genhotel Laboratoire de Recherche Europe ´en pour la Polyarthrite Rhumatoı¨de, Universite´ d’Evry-Val d’Essonne, ECRAF-Universite´ Paris 7-, 2 rue Gaston Cre´mieux, CP 5727 91057, Evry, France A. Rebai Unite´ de Bioinformatique, Centre de Biotechnologie de Sfax, BP. 3038 Sfax. Tunisie N.R. Farid Osancor Biotech Inc., Waltford, Herts, WD17 3BY, UK F. Cornelis Unite´ de Ge ´ne´tique clinique. Ho ˆpital Lariboisie `re, Assistance publique. Ho ˆpitaux de Paris, France 4 April 2006 doi:10.1016/j.clim.2006.04.565
235
[2] K. Wing, S. Lindgren, G. Kollberg, A. Lundgren, R.A. Harris, A. Rudin, S. Lundin, E. Suri-Payer, CD4 T cell activation by myelin oligodendrocyte glycoprotein is suppressed by adult but not cord blood CD25+ T cells, Eur. J. Immunol. 33 (2003) 579 – 587. [3] S. Lindley, C.M. Dayan, A. Bishop, B.O. Roep, M. Peakman, T.I. Tree, Defective suppressor function in CD4+CD25+ T-cells from patients with type 1 diabetes, Diabetes 54 (2005) 92 – 99. [4] R. Khattri, T. Cox, S.A. Yasayko, F. Ramsdell, An essential role for Scurfin in CD4+CD25+ T regulatory cells, Nat. Immunol. 4 (2003) 337 – 342. [5] S. Hori, T. Nomura, S. Sakaguchi, Control of regulatory T cell development by the transcription factor Foxp3, Science 299 (2003) 1057 – 1061.
Clare Baecher-Allan Center for Neurologic Disease, Brigham and Women s Hospital, 77 Avenue Louis Pasteur, Boston, MA 02115, USA E-mail address: [email protected]. 25 March 2006 doi:10.1016/j.clim.2006.03.013
Polymorphisms in the protein tyrosine phosphatase (PTPN22) gene is not associated with autoimmune thyroid in a large affected Tunisian family The pathogenesis of autoimmune thyroid diseases (AITDs) involves a complex interaction between genetic and environmental factors [1]. Several candidate genes have been examined for a possible contribution to genetic susceptibility to the AITDs by means of both association and linkage analyses [2]. An attractive candidate for additional susceptibility is PTPN22 (protein tyrosine phosphatase N22) that encodes a lymphoid-specific phosphatase known as Lyp and plays a key role as a negative regulator of T-cell activation by dephosphorylating T-cell receptor activation-dependent kinases. An additional function of Lyp is to downregulate activation of T-cells by binding to C-terminal Src tyrosine kinase (Csk), which is an important suppressor of kinases that mediate Tcell activation [3]. PTPN22 gene located on chromosome 1q13.3—13.1 harbors one functional SNP (rs 2476601) that leads to a change at codon 620 from arginine to a tryptophan (R620W). The minor allele of the R620W missense SNP has been associated with several autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, Hashimoto’s thyroiditis and type 1 diabetes [4]. Given the shared genetic susceptibility among autoimmune diseases and the association of PTPN22 gene, we investigated the PTPN22 polymorphism in a large Tunisian family (Akr family) composed of ten generations of more than 400 members, including 76 patients subdivided into 40 patients affected with GD, 13 patients with HT and 23 patients with Atrophic thyroiditis (PIM). The female/male ratio is 1 in GD patients, 3.3 in HT patients and 4.2 for
patients with PIM. Patients’ age at the onset of AITDs in this isolate ranged from 7 to 70 years (median age of 35 years). Fifty-six patients carried at least one HLA-DR11 susceptibility allele [5]. The dimorphism (C/T) was defined by PCR-RFLP method using XcmI enzyme. Two fragments of 173 and 42 bp were obtained after digestion when the PCR product containing the T allele. Statistical analysis was performed by family-based association test (FBAT) using empirical variance (the e option) [6]. We calculated FBAT scores under different models (recessive, additive and dominant) using 45 nuclear families with 167 individuals (extracted automatically by FBAT from Akr family). The FBAT analysis showed no significant association with R620W under the three models ( P = 0.19 for all models). Stratifying patients according to their phenotype (GD, HT and PIM) did not show any significant association with PTPN22 R620W allele ( P N 0.05). To establish whether PTPN22 association with AITDs was dependent on the presence of HLA-DR allele, the frequency of PTPN22 alleles was analyzed in the subgroup of patients who carried at least one HLA-DR11 allele. Our results failed to detect any evidence of interaction between PTPN22 C1858T dimorphism and HLA-DR11 ( P = 0.052). Based on these results, we conclude that C1858T polymorphisms of PTPN22 are unlikely to be associated with AITDs in the Akr family. Our results are in agreement with those reported by Ban et al. [7] on 334 unrelated Japanese patients with AITDs and 179 controls that showed negative association of C1858T polymorphisms with susceptibility to AITDs and our previous results indicating an absence of association between PTPN22 (C/T) dimorphism and RA in Tunisian case—control study ( P = 0.24) (unpublished results). Similar negative results have been reported for multiple sclerosis, Crohn disease and primary Sjo ¨gren’s syndrome [8—10]. This discrepancy of the associated allele may reflect genetic heterogeneity in the genetic basis of susceptibility to AITDs. In conclusion, the C1858T variant of PTPN22 does not appear to play a major role in AITDs pathogenesis in our data set. Analyses of the role of this SNP in additional autoimmune disorders should provide hints about the underlying mechanisms of these complex diseases as well as a framework to begin to understand how they are related and why some autoimmune diseases can cosegregate in the same families.
Acknowledgments Funding: AFP, ARP, Association Franc¸aise des Polyarthritiques, Association de Recherche pour la Polyarthrite, Association Polyarctique, SFR, Genopole (France), Ministe `re de l’Enseignement Supe ´rieur, Ministe `re la Recherche Scientifique et de la Technologie (Tunisie) and The International Centre for Genetic Engineering and Biotechnology (ICGEB) Trieste (Italy).
References [1] Y. Tomer, T.F. Daves, Infection thyroid disease and autoimmunity, Endocr. Rev. 14 (1993) 107 – 120. [2] H. Ayadi, H. Hadj Kacem, A. Rebai, N.R. Farid, The genetics of autoimmune thyroid disease, Trends Endocrinol. Metab. 15 (2004) 234 – 239.
236 [3] S. Cohen, H. Dadi, E. Shaoul, N. Sharfe, C.M. Roifman, Cloning and characterization of a lymphoid specific inducible human protein tyrosine phosphatase Lyp, Blood 93 (1999) 2013 – 2024. [4] L.A. Criswell, K.A. Pfeiffer, R.F. Lum, B. Gonzales, J. Novitzke, M. Kern, K.L. Moser, A.B. Begovich, V.E. Carlton, W. Li, A.T. Lee, W. Ortmann, T.W. Behrens, P.K. Gregersen, Analysis of families in the multiple autoimmune disease genetics consortium (MADGC) collection: the PTPN22 620W allele associates with multiple autoimmune phenotypes, Am. J. Hum. Genet. 76 (2005) 561 – 571. [5] N. Elleuch-Bougacha, A. Maalej, H. Makni, M. Bellassouad, M. Abid, J. Jouida, K. Ayed, D. Charron, R. Tamouza, H. Ayadi, HLA class I and II polymorphisms in a large multiplex family with autoimmune thyroid diseases, Clin. Endocrinol. (Oxford) 55 (2001) 163 – 557. [6] D. Rabinowitz, M.N. Laird, A unified approach to adjusting association tests for population admixture with arbitrary pedigree structure and arbitrary missing marker information, Hum. Hered. 50 (2000) 211 – 223. [7] Y. Ban, T. Tozaki, M. Taniyama, M. Tomita, Y. Ban, The codon 620 single nucleotide polymorphism of the protein tyrosine phosphatase 22 gene does not contribute to autoimmune thyroid disease susceptibility in the Japanese, Thyroid 15 (2005) 1115 – 1118. [8] A.B. Begovich, S.J. Caillier, H.C. Alexander, J.M. Penko, S.L. Hauser, L.F. Barcellos, J.R. Oksenberg, The R620W polymorphism of the protein tyrosine phosphatase PTPN22 is not associated with multiple sclerosis, Am. J. Hum. Genet. 76 (2005) 184 – 187. [9] S.E. Wagenleiter, W. Klein, T. Griga, W. Schmiegel, J.T. Epplen, P. Jagiello, A case—control study of tyrosine phosphatase (PTPN22) confirms the lack of association with Crohn’s disease, Int. J. Immunogenet. 32 (2005) 323 – 324. [10] M. Ittah, J.E. Gottenberg, A. Proust, A. Hachulla, X. Puechal, P. Loiseau, X. Mariette, C. Miceli-Richard, No evidence for association between 1858 C/T single-nucleotide polymorphism of PTPN22 gene and primary Sjogren’s syndrome, Genes. Immun. 6 (2005) 457 – 458.
LETTERS TO THE EDITOR G. Chabchoub A. Maalej H. Ayadi* Laboratoire de Ge ´ne´tique Mole´culaire Humaine, Faculte´ de Me ´decine, Avenue Majida Boulila 3029 de Sfax, Tunisie E-mail address: [email protected]. *Corresponding author. Fax: +216 74 461 403. E. Petit-Teixeira E. Glikmans F. Cornelis Genhotel Laboratoire de Recherche Europe ´en pour la Polyarthrite Rhumatoı¨de, Universite´ d’Evry-Val d’Essonne, ECRAF-Universite´ Paris 7-, 2 rue Gaston Cre´mieux, CP 5727 91057, Evry, France A. Rebai Unite´ de Bioinformatique, Centre de Biotechnologie de Sfax, BP. 3038 Sfax. Tunisie N.R. Farid Osancor Biotech Inc., Waltford, Herts, WD17 3BY, UK F. Cornelis Unite´ de Ge ´ne´tique clinique. Ho ˆpital Lariboisie `re, Assistance publique. Ho ˆpitaux de Paris, France 4 April 2006 doi:10.1016/j.clim.2006.04.565