title: The CTLA4 region as a general autoimmunity factor: an extended pedigree provides evidence for synergy with the HLA locus in the etiology of type 1 diabetes mellitus, Hashimoto's thyroiditis and Graves' disease.
abstract: We have identified a large family in the northern part of Sweden with multiple cases of autoimmune diseases, namely type 1 diabetes (T1D), Graves' disease (GD) and Hashimoto's thyroiditis (HT). The family members affected by any of these diseases share a region of 2.4 Mb that comprises among others the CTLA4 gene. We determined that all affected members of the family shared the HLA susceptibility haplotype (DR4-DQA1*0301-DQB1*0302). Analysis of genetic interaction conditioning for HLA haplotype provided strong evidence that the critical region which includes the CTLA4 gene acts together with the HLA locus on the etiology of disease (lodscore 4.20 (theta=0.0). The study of this family allowed us to: (1) reinforce a number of reports on linkage and association of the CTLA4 region to T1D and AITD; (2) demonstrate that a single haplotypic variant in this region constitutes an etiological factor to disease susceptibility in T1D, GD and HT; (3) reveal a strong genetic interaction of the CTLA4 and HLA loci in the genetic architecture of autoimmune disease; (4) emphasise the value of large pedigrees drawn from isolated populations as tools to single out the effect of individual loci in the etiology of complex diseases.
authors.affiliation: Umeå Centre for Molecular Medicine, Umeå University, Sweden.
authors.forename: Elisabet
authors.initials: E
authors.lastname: Einarsdottir
authors.forename: Ingegerd
authors.initials: I
authors.lastname: Söderström
authors.forename: Anna
authors.initials: A
authors.lastname: Löfgren-Burström
authors.forename: Susann
authors.initials: S
authors.lastname: Haraldsson
authors.forename: Sofie
authors.initials: S
authors.lastname: Nilsson-Ardnor
authors.forename: Carlos
authors.initials: C
authors.lastname: Penha-Goncalves
authors.forename: Lisbet
authors.initials: L
authors.lastname: Lind
authors.forename: Gösta
authors.initials: G
authors.lastname: Holmgren
authors.forename: Monica
authors.initials: M
authors.lastname: Holmberg
authors.forename: Kjell
authors.initials: K
authors.lastname: Asplund
authors.forename: Dan
authors.initials: D
authors.lastname: Holmberg
mesh_terms: D000069594:Abatacept; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000235:genetics*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics; D015551:Autoimmunity / Q000235:genetics*; D018106:CD28 Antigens / Q000235:genetics; D060908:CTLA-4 Antigen; D003922:Diabetes Mellitus, Type 1 / Q000209:etiology / Q000235:genetics*; D008040:Genetic Linkage; D005819:Genetic Markers; D006111:Graves Disease / Q000209:etiology / Q000235:genetics*; D006680:HLA Antigens / Q000235:genetics / Q000276:immunology; D006239:Haplotypes / Q000235:genetics; D006801:Humans; D018796:Immunoconjugates; D060889:Inducible T-Cell Co-Stimulator Protein; D008126:Lod Score; D009154:Mutation; D010375:Pedigree; D013548:Sweden; D013967:Thyroiditis, Autoimmune / Q000209:etiology / Q000235:genetics*
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D000945:Antigens, Differentiation, T-Lymphocyte; D018106:CD28 Antigens; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; D005819:Genetic Markers; D006680:HLA Antigens; C556692:ICOS protein, human; D018796:Immunoconjugates; D060889:Inducible T-Cell Co-Stimulator Protein; D000069594:Abatacept