EVALUATION OF TAP1 POLYMORPHISMS WITH INSULIN-DEPENDENT DIABETES-MELLITUS IN FINNISH DIABETIC-PATIENTS

Insulin dependent diabetes mellitus (IDDM) is an autoimmune disease wi th a strong association between disease and the HLA class II region. B ecause abnormal antigen processing, in part characterized by altered c lass I processing, has been identified in patients with IDDM, the TAP (transporter associated with antigen processing) genes located in the HLA class II region make attractive candidate genes for IDDM. Five cod ing region variants of TAP1 were typed in a cohort of well characteriz ed Finnish patients with diabetes (n = 119) and compared to racially m atched control subjects (n = 92). We found that although no single TAP 1 polymorphism was associated with IDDM, a genotypic combination of Il e/Val at codon 333 with Asp/Asp at codon 637 was found more frequently in subjects with IDDM (9.4%) compared to controls (1.2%; P = 0.025). This could not be accounted for by an association with any particular haplotype defined by class I or class II serology. (C) American Societ y for Histocompatibility and Immunogenetics, 1997.