GAD65 antibody prevalence and association with thyroid antibodies, HLA-DR in Chinese children with type I diabetes mellitus

Persistent humoral autoimmunity to the enzyme glutamic acid decarboxylase ( GAD) has been described in a substantial proportion of patients with type I diabetes mellitus. Higher prevalence of GAD antibody in diabetes patients using a new radioligand-binding assay with recombinant human GAD65 antibodi es (GAD65Ab) has been seen in several studies. Using this method, we have r eassessed the prevalence of GAD65Ab and investigated the association of GAD 65Ab with HbAlC values, C-peptide values, HLA-DR typing and thyroid autoimm une antibody in 70 Chinese children with type I diabetes mellitus (mean age of onset 8.21 +/- 3.84 years. mean duration 3.39 +/- 2.54 years). Our resu lt revealed that GAD65 antibodies were present in 54.3% (38/70) of diabetes children. There was no significant difference in gender, diabetes onset an d duration, HbAlc, C-peptide concentration and frequencies of HLA DR3, DR4, DR9, DR3/DR4, DR3/DR9 and DR4/DR9 genotypes between GAD65Ab(+) and GAD65Ab (-) groups. There was no negative correlation between GAD65Ab values and du ration of diabetes in those with GAD65Ab positivity (r = -0.239, P > 0.05). The frequencies of antimicrosomal and anti-thyroglobulin antibodies in GAD 65Ab(+) (13.5, 8.1%, respectively) were not different from GAD65(-) patient s (9.4, 12.5%, respectively). (C) 2001 Elsevier Science Ireland Ltd. All ri ghts reserved.