title: A study of type-1 diabetes associated autoantibodies in schizophrenia.
abstract: Epidemiological studies revealed an association between type-1 diabetes (T1D) and schizophrenia but the findings reported to date have been controversial. To clarify the inconsistency across studies, T1D-associated autoantibodies were examined in plasma samples collected from 272 patients with schizophrenia and 276 control subjects. An in-house enzyme-linked immunosorbent assay (ELISA) was developed using three linear peptide antigens, one of which was derived from glutamic acid decarboxylase (GAD) and two were derived from insulinoma-associated antigen 2 (IA2). Mann-Whitney U test showed a significant decrease in the levels of plasma IgG against the IA2b antigen in schizophrenia patients as compared to control subjects (Z=-3.54, p=0.0007), while no significant difference was found between these two groups either in anti-IA2a IgG levels (Z=-1.62, p=0.105) or in anti-GAD IgG levels (Z=-1.63, p=0.104). Linear regression analysis indicated no association of antipsychotic medication with the levels of plasma IgG against IA2a, IA2b or GAD, while the levels of plasma IgG for these 3 peptide antigens were significantly correlated with each other. Binary logistic regression showed that neither the DQ2.5 variant nor the DQ8 variant was associated with circulating levels of 3 T1D-associated autoantibodies in both the patient group and the control group. The coefficient of variation was 10.7% for anti-IA2a IgG assay, 10.1% for anti-IA2b IgG assay and 10.7% for anti-GAD IgG assay. The present work suggests that T1D-associated antibodies are unlikely to confer risk of schizophrenia and that the in-house ELISA developed with linear peptide antigens is highly reproducible.
authors.affiliation: Division of Health Research, University of the Highlands and Islands, Centre for Health Science, Old Perth Road, Inverness IV2 3JH, UK.
authors.forename: Philomena
authors.initials: P
authors.lastname: Hallford
authors.affiliation: Department of Medicine and Dentistry, University of Aberdeen, Aberdeen AB25 2ZD, UK.
authors.forename: David St
authors.initials: DS
authors.lastname: Clair
authors.affiliation: Division of Health Research, University of the Highlands and Islands, Centre for Health Science, Old Perth Road, Inverness IV2 3JH, UK.
authors.forename: Lorna
authors.initials: L
authors.lastname: Halley
authors.affiliation: Division of Health Research, University of the Highlands and Islands, Centre for Health Science, Old Perth Road, Inverness IV2 3JH, UK.
authors.forename: Colette
authors.initials: C
authors.lastname: Mustard
authors.affiliation: Division of Health Research, University of the Highlands and Islands, Centre for Health Science, Old Perth Road, Inverness IV2 3JH, UK. Electronic address: jun.wei@uhi.ac.uk.
authors.forename: Jun
authors.initials: J
authors.lastname: Wei
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000627:therapeutic use; D001323:Autoantibodies / Q000097:blood*; D016022:Case-Control Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000235:genetics / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005968:Glutamate Decarboxylase / Q000276:immunology; D006680:HLA Antigens / Q000235:genetics; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D012306:Risk; D012559:Schizophrenia / Q000097:blood* / Q000188:drug therapy / Q000235:genetics / Q000276:immunology*
chemical_list: D014150:Antipsychotic Agents; D001323:Autoantibodies; D006680:HLA Antigens; D007074:Immunoglobulin G; D005968:Glutamate Decarboxylase
keywords: Autoantibody; ELISA; Schizophrenia; Type-1 diabetes