Frequency of islet cell autoantibodies (IA-2 and GAD) in young Brazilian type 1 diabetes patients

Type 1 diabetes, as an autoimmune disease, presents several islet cell-spec ific autoantibodies such as islet cell antibody (ICA), anti-insulin, anti-g lutamic acid decarboxylase (GAD) and the antibody (Ab) against tyrosine pho sphatase (PTP)-like protein known as ICA-512 (IA-2). In order to determine the frequency of the anti-GAD and anti-IA-2 autoantibodies in Brazilian typ e 1 diabetes patients we studied 35 diabetes mellitus (DM) type 1 patients with recent-onset disease (less than or equal to 12 months) and 37 type 1 d iabetes patients with long-duration diabetes (>12 months) who were compared to 12 children with normal fasting glucose. Anti-GAD(65) and anti-IA-2 aut oantibodies were detected with commercial immunoprecipitation assays. The f requency of positive results in recent-onset DM type I patients was 80.0% f or GADAb, 62.9% for IA-2Ab and 82.9% for GADAb and/or IA-2Ab. The long dura tion type 1 diabetes subjects presented frequencies of 54.1% for GADAb and IA-2Ab, and 67.5% for GAD and/or IA-2 antibodies. The control group showed no positive cases. Anti-GAD and IA-2 assays showed a high frequency of posi tivity in these Brazilian type 1 diabetes patients, who presented the same prevalence as a Caucasian population.