title: Thyroid autoantibodies in HLA-genotyped type 1 diabetic families: sex-limited DR5 association with thyroid microsomal antibody.
abstract: Thyroid autoantibodies are common in Type 1 diabetics and their first degree relatives and may be part of the autoimmune diathesis present within such families. We have measured the prevalence of microsomal (M-Ab) and thyroglobulin (Tg-Ab) autoantibodies in 84 HLA-typed families having a Type 1 diabetic child, using enzyme-linked immunosorbent assay techniques. Thyroid autoantibodies were detectable in 201/407 (49%) individuals in these families. Both autoantibodies were significantly more frequent in the subsets of parents, diabetic children and their non-diabetic siblings than in groups of control adults and children. The prevalence of these autoantibodies in the diabetic families was increased in both sexes with a female:male ratio of 1.4:1. Antigen DR5 was significantly associated with M-Ab production but only for male subjects (P = 0.005 after correction for the number of DR antigens tested). No significant associations were encountered for Tg-Ab. Within-family analyses indicated that thyroid autoantibodies occurred with increased prevalence in HLA-identical or haplo-identical siblings of autoantibody-positive index cases in comparison to control children. We conclude the DR association with thyroid autoantibody production in this diabetes-selected population was thyroiditis-related and not diabetes-related, and the DR5 association was restricted to males and the production of M-Ab. These data are consistent with the hypothesis that multiple genetic and non-genetic factors played a role in the high prevalence of thyroid autoantibodies in this population.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006680:HLA Antigens / Q000032:analysis; D006650:Histocompatibility Testing; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D013961:Thyroid Gland / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D006680:HLA Antigens