title: Tyrosine phosphatase-like protein (IA-2) and glutamic acid decarboxylase (GAD65) autoantibodies: a study of Chinese patients with diabetes mellitus.
abstract: Type 1 diabetes in most Asian populations may not have a salient autoimmune basis when assessed with single determinations of the major markers, islet cell antibodies (ICAs) and glutamic acid decarboxylase antibodies (GAD65ab). With the inclusion of antibodies to tyrosine phosphatase-like protein IA-2 (IA-2ab) as an additional major marker, we re-examined autoimmune diabetes in a group of Chinese patients. We studied 272 subjects at various stages of disease with blood samples procured for biochemical analysis. ICAs were measured by immunofluorescence, GAD65ab and IA-2ab by radioimmunoassay. Sixty-seven patients fulfilled clinical diagnosis of type 1 diabetes and the remaining 205 patients were type 2. Prevalence of single autoantibody type in recent-onset type 1 diabetes ( < 1 year duration; n = 47) showed 10.6% with ICAs, 44.7% GAD65ab and 36.2% IA-2ab. GAD65ab account for more than two-thirds of the markers found in type 1 diabetes. Combined analysis further showed that 51.1% had at least one antibody type, 31.9% with two or more antibodies and 8.5% with all three antibodies. Islet autoimmunity presence in childhood-onset type 1 diabetes improved with the addition of IA-2ab, though less impact was seen in the adult-onset. Similarly, combined analysis for type 2 patients with recent diabetes showed a modest increase to 13% with islet autoimmunity compared to 8% when assessed by GAD65ab alone. Combining IA-2ab and GAD65ab assays results detected slightly more immune-mediated diabetes, compared to using a single GAD65ab determination. Non-autoimmune causes need to be considered in the pathogenesis of type 1 diabetes in Chinese, particularly in adults.
authors.affiliation: Department of Medicine, National University of Singapore, Republic of Singapore. mdcngwy@nus.edu.sg
authors.forename: W Y
authors.initials: WY
authors.lastname: Ng
authors.forename: Y S
authors.initials: YS
authors.lastname: Lee
authors.forename: A L
authors.initials: AL
authors.lastname: Todd
authors.forename: K F
authors.initials: KF
authors.lastname: Lui
authors.forename: K Y
authors.initials: KY
authors.lastname: Loke
authors.forename: A C
authors.initials: AC
authors.lastname: Thai
mesh_terms: D000328:Adult; D044466:Asian People; D001323:Autoantibodies / Q000097:blood / Q000276:immunology*; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000175:diagnosis / Q000201:enzymology / Q000276:immunology*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000175:diagnosis / Q000201:enzymology / Q000276:immunology*; D005260:Female; D005968:Glutamate Decarboxylase / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000276:immunology* / Q000378:metabolism; D008297:Male; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000276:immunology* / Q000378:metabolism; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8
chemical_list: D001323:Autoantibodies; D007527:Isoenzymes; C516862:PTPRN protein, human; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8; D005968:Glutamate Decarboxylase; C401141:glutamate decarboxylase 2