The Preliminary Research On The Genetic Susceptibility To Autoimmune Thrombocytopenia

Background and objective:Lymphoid tyrosine phosphatase （LYP） is a protein tyrosine phosphatase （PTP） encoded by the gene of protein tyrosine phosphatase nonreceptor22（PTPN22）. LYP plays a negative role in T cell signaling. The polymorphisms of PTPN22gene have been reported to be associated with susceptibilities to numerous autoimmune diseases. Immune Thrombocytopenia （ITP） is an acquired organ-specific autoimmune disease. The purpose of this study was to investigate whether the PTPN22-1123C>G polymorphism contributes to risk of ITP.Method:Genotyping of PTPN22-1123G>C （rs2488457） polymorphism was performed using polymerase chain reaction-matrix assisted laser desorption/ionization time-of-flight mass spectrometry （PCR-MALDI-TOF MS）. Total subjects of191ITP patients and216healthy controls were enrolled in the case-control study.Results:The major allele of the-1123site was C, with a frequency of70.6%vs.29.4%for allele G in normal controls. The allele and genotype distribution of-1123G>C was significantly skewed in ITP patients, who had significantly higher frequencies of G allele and GG genotype than normal control （P=0.034; P=0.038）. Odds ratios （ORs） and95%confidence interval （95%CI） for G allele, GG and GC genotypes were1.374（1.024～1.843）,1.951（1.031～3.694）,1.253（0.825～1.902）, respectively. Comparable observations were made in the stratified analysis. Both subgroups of male and adult-onset patients exhibited significantly elevated distribution of G allele and GG genotype accompanied with increased ORs for developing ITP when comparing with matched controls. Similar trend occurred in cohort of chronic patients, with a P value of almost0.08. The-1123G frequency is higher in female controls than in male ones, with a borderline P value of0.055.Conclusion:Our results demonstrate that PTPN22-1123G is a susceptibility factor to developing ITP. And it works in a dose-dependent manner.-1123G>C polymorphism might play different roles in distinct ITP cohorts. Higher frequency of-1123G might be an important genetic risk factor for the increased incidence of ITP in female. It is confirmed at least that-1123G can be used as an independent predictor for male ITP and adult-onset ITP. Whether or not does-1123G contribute to chronic ITP needs to be further studied by larger samples. Background and objective:Interferons （IFNs） are the most pleiotropic molecules which influence both the innate and adaptive immune responses. In the past decades, extensive studies revealed crucial roles for type Ⅰ IFN in pathogenesis of SLE and Sjogren’s syndrome. Interferon regulatory factor5（IRF5） is a member of IRF family that plays an important role as a master transcription factor for genes of inflammatory cytokines and type Ⅰ interferon. The signal transducer and activator of transcription4（STAT4） could be activated by cytokines, including type Ⅰ IFN, interleukin-12and interleukin-23, then stimulates the differentiation of Thl and Th17. Tyrosine kinase2（TYK2） binds to the type Ⅰ IFN receptor complex with JAK1and initiates a JAK/STAT signaling cascade leading to the transcription of IFN signature genes. All of the three mentiend above are important components of the type Ⅰ IFN system. ITP is an organ-specific autoimmune disease. It was proposed that IFN system may involved in pathogenesis of ITP. The aim of the study was to determine the associations between polymorphisms of the three genes with ITP.Method:Genotyping of length polymorphisms3*/4*CGGGG and30bpIn/Del in IRF5was performed using polymerase chain reaction followed by agarose gels electrophoresis. rs3821236and rs2304256were detected by polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） assay, while rs10954231and rs7574865by means of polymerase chain reaction-matrix assisted laser desorption/ionization time-of-flight mass spectrometry （PCR-MALDI-TOF MS）. Total subjects of159ITP patients and196healthy controls were enrolled in the case-control study.Result:Polymorphisms of IRF530bpIn/Del, TYK2rs2304256, STAT4rs7574865and rs3821236were shown to be associated with ITP （P=0.024,0.036,0.029,0.019, respectively）. These associations were not restricted to a particular phenotype after the stratified analysis. We also investigated an addictive effect of the four polymorphisms on the risk for developing ITP.Conclusion:Polymorphisms of30bpIn/Del, rs7574865, rs3821236and rs2304256correlated with susceptibility to Immune Thrombocytopenia. As all the polymorphisms located in genes related to type ⅠIFN system, we supposed that type Ⅰ IFN system dysfunction may be an important aspect of ITP pathogenesis. Combined factor Ⅴ-factor Ⅷ deficiency （F5F8D） is a rare, autosomal recessive disorder caused by mutations in genes of either lmanl or mcfd2. To identify mutations of these two genes in a Chinese F5F8D family, samples of peripheral blood were collected from the proband and her parents. Coagulation tests were carried out including activated partial thromboplastin time （APTT）, prothrombin time （PT）, thrombin time （TT）, fibrinogen（Fg） and coagulate activity of FⅤ, FⅧ （FⅤ:C, FⅧ:C）. The genomic DNA was extracted, then, all the exons and intron/exon boundaries of these two genes were amplified by polymerase chain reaction （PCR）. The products were finally analyzed by direct sequencing. According to the laboratory report, the proband’s APTT, PT, TT, Fg, FⅤ:C and FⅧ：C were82.2S,19.6S,18.6S,2.9g/l,7.1%and18.7%respectively, while those of the parents’ were all between the normal range. Two pathogenic mutations were identified in lmanl gene of the proband:one was the heterozygous c.912₉13insA in exon8resulting in a frameshift of p.Glu305fsX20; the other was the heterozygous c.1366C>T in exon11resulting in p.Arg456X.The proband’s father and mother were heterozygous for c.1366C>T and c.912₉13insA respectively. So we drew a conclusion that F5F8D of the proband was caused by a novel compound heterozygosity of the lmanl gene, which had never been reported.