Predisposition to idiopathic thrombocytopenic purpura maps close to the major histocompatibility complex class I chain-related gene A.

Idiopathic thrombocytopenic purpura (ITP) is an autoimmune condition with poorly known etiology, characterized by platelet destruction. Genetic association studies of this disease are scarce, discrepant, and restricted to major histocompatibility complex (MHC) polymorphisms. Hence, a case-control study was conducted with an aim to map the MHC to IPT susceptibility using HLA-B and nine microsatellite loci encompassing MHC class I, II, and III regions. We compared the allelic frequencies in samples of unrelated healthy controls and ITP patients. After correction for multiple tests, only allele MICA*183, also known as A5.1, demonstrated an association, resulting in the identification of a major predisposing region close to STR-MICA. This result may highlight the putative functional role of MICA in the immune response to ITP.