A MUTATION IN THE GENE PTPN22 AS AN INDICATOROF RISK IN IDIOPATHIC THROMBOCYTOPENIC PURPURAByMatthew B. ZamoraImmune-mediated thrombocytopenic purpura (ITP) is an autoimmune disorder characterized by low platelet count and antibody mediated platelet destruction. ITP may be due to a failure of T-cell tolerance. Protein tyrosine phosphatase non receptor type 22 (PTPN22) is an important negative regulator of signal transduction from the T cell receptor. A single nucleotide polymorphism 1858C>T in the PTPN22 gene has been associated with various autoimmune disorders with an autoantibody component. We hypothesize that the PTPN22 mutation 1858C>T would be present in a higher proportion of ITP patients due to the humoral immunological component of the disease. We genotyped 45 patients with ITP by a Polymerase Chain Reaction (PCR) based restriction length polymorphism(RFLP) to identify the mutation 1858C>T in the gene PTPN22. Ten patients (22.2%) were heterozygous for the PTPN22 mutation and 2 were homozygous for the mutation (4.4%). The allele frequency of T allele in this ITP group is 15.5%. This compares with a T allele frequency of 8.6% observed in a published population study of 926 controls. Our results indicate that PTPN22 mutation allele is increased in ITP patients when compared to this control group with a P value of 0.02.
Read
