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191 - Anti-Pancreatic islet cell antibodies in type I diabetes mellitus and in latent autoimmune diabetes in adults (LADA)

Autor(s): A. Falorni per il Gruppo di Studio intersocietario SIBioC-SIMeL Diabete mellito

Issue: RIMeL - IJLaM, Vol. 5, N. 3, 2009 (MAF Servizi srl ed.)

Page(s): 191-205

Summary
Islet autoimmunity is made evident by the appearance of islet cell antibodies directed against insulin (IAA), glutamic acid decarboxylase (GADA), protein tyrosine phosphatase IA-2 (IA-2A) and other autoantigens. Islet autoantibodies are not pathogenic, but they are useful markers of the ongoing autoimmune process. IAA and IA-2A are predominantly detected in childhood type 1 diabetes mellitus (T1DM), while frequency of GADA is not affected by age at disease onset. In adult-onset T1DM patients, GADA is the immune marker at higher diagnostic sensitivity. In adult diabetic patients who do not require insulin treatment for at least 6 months after diagnosis, GADA identify the so-called latent autoimmune diabetes in adults (LADA). In over 80% of cases, LADA patients develop insulin dependency within a few years after the diagnosis and have an increased risk for development of other organ-specific autoimmune diseases. High GADA titres identify a subgroup of LADA patients with low body mass index (BMI), low C-peptide levels and increased frequency of T1DM-related HLA class II haplotypes. Therefore, GADA assay should be offered to adult diabetic patients to identify cases with latent autoimmunity, and in case of positivity, screening for other autoimmune diseases should be carried out. Commercial kits for GADA and IA-2A are currently available. The choice of the specific assay should take into consideration the proficiency in international workshops of standardization, such as the Diabetes Antibody Standardization Program (DASP). Key-words: Autoimmunity, ELISA, Glutamic Acid Decarboxylase, Insulin, Islet-cell antibodies, RIA.

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