Antibodies to GAD65 and a tyrosine phosphatase-like molecule IA-2ic in Filipino type 1 diabetic patients.
OBJECTIVE
Type 1 diabetes is more prevalent in Europeans than it is in Asians. The disease is associated with autoantibodies to GAD65 and a protein tyrosine phosphatase-like molecule (IA-2). The frequency of GAD antibodies in Asian patients with type 1 diabetes may be lower than that in Europeans. No data are available on IA-2 antibodies in Asians. We tested antibodies to GAD65 and IA-2ic (the intracellular fragment containing the antibody epitope) in Filipino diabetic patients because this population has mixed European and aboriginal racial origins.


METHODS
A cross-sectional study of antibodies to GAD65 and IA-2ic was performed on a consecutive series of 91 type 1 diabetic patients, 74 type 2 diabetic patients, and 100 control subjects attending a diabetes clinic in Manila, the Republic of the Philippines. All subjects were <40 years of age, with a mean age +/- SD of 24.8+/-9.8, 34.3+/-5.8, and 25.8+/-8.0 years, respectively. Diagnosis of type 1 diabetes was determined clinically and confirmed by baseline C-peptide.


RESULTS
Of 91 type 1 diabetic patients, antibodies to GAD65 were detected in 25 (27.4%), but antibodies to IA-2ic were found in only 8 (8.8%) (P = 0.002); neither autoantibody was detected in either the type 2 diabetic or control subjects. Of the 25 recently diagnosed type 1 diabetic patients (disease duration <2.0 years), autoantibodies to GAD65 were detected in 14 (56%), but those to IA-2ic in only 4 (16%) (P = 0.007); GAD65 antibodies were detected in only 4 (6%) of 66 patients with a longer disease duration (P = 0.0004). Comparison with recently diagnosed European type 1 diabetic patients of age and disease duration similar to that of the Filipinos indicated that IA-2ic antibodies, unlike GAD antibodies, were significantly less prevalent in Filipino type 1 diabetic patients (P = 0.0007).


CONCLUSIONS
This is the first study investigating the prevalence and pattern of humoral immune response in type 1 diabetic patients from the Philippines. Antibodies to IA-2ic, unlike GAD antibodies, were infrequent. Patterns of immune responses to type 1 diabetes-associated antigens may differ worldwide, with important implications for prediction of the disease and the potential for antigen-specific therapy.
Medici
F
F
Department of Diabetes and Metabolism, St. Bartholomew's Hospital, London, UK.
Hawa
M I
MI
Giorgini
A
A
Panelo
A
A
Solfelix
C M
CM
Leslie
R D
RD
Pozzilli
P
P
D000328:Adult; D001323:Autoantibodies / Q000097:blood*; D003430:Cross-Sectional Studies; D003922:Diabetes Mellitus, Type 1 / Q000201:enzymology / Q000276:immunology / Q000503:physiopathology*; D000939:Epitopes; D005060:Europe; D005260:Female; D005968:Glutamate Decarboxylase / Q000276:immunology*; D006801:Humans; D007527:Isoenzymes / Q000276:immunology*; D008297:Male; D010679:Philippines / Q000208:ethnology; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000276:immunology*; D012016:Reference Values
D001323:Autoantibodies; D000939:Epitopes; D007527:Isoenzymes; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; D005968:Glutamate Decarboxylase