DNA methyltransferase 3B (DNMT3B -579G>T) promotor polymorphism and the susceptibility to pediatric immune thrombocytopenic purpura in Egypt

Translating mechanisms into therapeutic strategies for immune thrombocytopenia (ITP): Lessons from clinical trials

Immune thrombocytopenia (ITP) is an autoimmune disorder that causes a significant reduction in peripheral blood platelet count. Fortunately, due to an increased understanding of ITP, there have been significant improvements in the diagnosis and treatment of these patients. Over the past decade, there have been a variety of proven therapeutic options available for ITP patients, including intravenous immunoglobulins (IVIG), Rituximab, corticosteroids, and thrombopoietin receptor agonists (TPO-RAs). Although the effectiveness of current therapies in treating more than two-thirds of patients, still some patients do not respond well to conventional therapies or fail to achieve long-term remission. Recently, a significant advancement has been made in identifying various mechanisms involved in the pathogenesis of ITP, leading to the development of novel treatments targeting these pathways. It seems that new agents that target plasma cells, Bruton tyrosine kinase, FcRn, platelet desialylation, splenic tyrosine kinase, and classical complement pathways are opening new ways to treat ITP. In this study, we reviewed the pathophysiology of ITP and summarized updates in this population's management and treatment options. We also took a closer look at the 315 ongoing trials to investigate their progress status and compare the effectiveness of interventions. May our comprehensive view of ongoing clinical trials serve as a guiding beacon, illuminating the path towards future trials of different drugs in the treatment of ITP patients.

The role of epigenetics in childhood autoimmune diseases with hematological manifestations

Autoimmune diseases with hematological manifestations are often characterized by chronicity and relapses despite treatment, and the underlying pathogenetic mechanisms remain unknown. Epigenetic alterations play a vital role in the deregulation of immune tolerance and the development of autoimmune diseases. In recent years, study of epigenetic mechanisms in both adult and childhood autoimmune disorders has been seeking to explain the pathophysiology of these heterogeneous diseases and to elucidate the interaction between genetic and environmental factors. Various mechanisms, including DNA methylation, histone modifications (chromatin remodeling), and noncoding RNAs (ncRNAs), have been studied extensively in the context of autoimmune diseases. This paper summarizes the epigenetic patterns in some of the most common childhood autoimmune disorders with hematological manifestations, based on epigenetic studies in children with primary immune thrombocytopenia (ITP), systemic lupus erythematosus (SLE), and juvenile idiopathic arthritis (JIA). Research findings indicate that methylation changes in genes expressed on T cells, modifications at a variety of histone sites, and alterations in the expression of several ncRNAs are involved in the pathogenesis of these diseases. These mechanisms not only determine the development of these diseases but also affect the severity of the clinical presentation and biochemical markers. Further studies will provide new tools for the prevention and diagnosis of childhood autoimmune disorders, and possible novel treatment options.

Association of DNA Methyltransferase 3B Promotor Polymorphism With Childhood Chronic Immune Thrombocytopenia

BACKGROUND

DNA methylation is an epigenetic process that refers to chromatin-based mechanisms in the regulation of gene expression without DNA alternation. It is mediated by DNA methyltransferases (DNMTs). The DNA methyltransferase 3B (DNMT3B) gene contains a C-to-T single nucleotide polymorphism (SNP; rs2424913) in the Promotor region, 149 base pairs from the transcription start site, which is reported to significantly increase the Promotor activity.

OBJECTIVE

To investigate the prevalance of rs2424913 single nucleotide polymorphism located in the DNMT3B gene Promotor.

METHODS

In the present study, we investigated the prevalence of rs2424913 single nucleotide polymorphism located in DNMT3B gene Promotor by restriction fragment length polymorphism (PCR-RFLP) in Egyptian pediatric chronic immune thrombocytopenia (ITP) patients and controls.

RESULTS

The homozygous genotype (TT) was significantly higher in our patient and conferred almost 3-fold increased risk of chronic ITP when compared to controls.

CONCLUSION

The present study shows that DNMT3B rs2424913 promotor polymorphism represents a genetic risk factor that may play an important role in understanding the pathogenesis of chronic ITP.

Clinical and laboratory predictors of chronic immune thrombocytopenia in children: a systematic review and meta-analysis

Childhood immune thrombocytopenia (ITP) is a rare autoimmune bleeding disorder. Most children recover within 6 to 12 months, but individual course is difficult to predict. We performed a systematic review and meta-analysis to identify predictors of chronic ITP. We found 1399 articles; after critical appraisal, 54 studies were included. The following predictors of chronic ITP in children, assessed in at least 3 studies, have been identified: female gender (odds ratio [OR] 1.17, 95% confidence interval [CI] 1.04-1.31), older age at presentation (age ≥11 years; OR 2.47, 95% CI 1.94-3.15), no preceding infection or vaccination (OR 3.08, 95 CI 2.19-4.32), insidious onset (OR 11.27, 95% CI 6.27-20.27), higher platelet counts at presentation (≥20 × 10(9)/L: OR 2.15, 95% CI 1.63-2.83), presence of antinuclear antibodies (OR 2.87, 95% 1.57-5.24), and treatment with a combination of methylprednisolone and intravenous immunoglobulin (OR 2.67, 95% CI 1.44-4.96). Children with mucosal bleeding at diagnosis or treatment with intravenous immunoglobulin alone developed chronic ITP less often (OR 0.39, 95% CI 0.28-0.54 and OR 0.71, 95% CI 0.52-0.97, respectively). The protective effect of intravenous immunoglobulin is remarkable and needs confirmation in prospective randomized trials as well as future laboratory studies to elucidate the mechanism of this effect.

Association of DNA methyltransferases 3A and 3B polymorphisms, and plasma folate levels with the risk of urothelial carcinoma

BACKGROUND

Interindividual genetic variations of human DNA methyltransferases (DNMTs), which involve the methyl donor from the folate-related one-carbon metabolism pathway, are hypothesized as a risk factor for urothelial carcinoma (UC). Therefore, we evaluated the role of gene-environment interaction in UC carcinogenesis.

METHODS

A hospital-based case-control study was conducted by recruiting 192 patients with UC and 381 controls. Their plasma folate levels were measured using a competitive immunoassay kit. In addition, DNMT3A -448A>G and DNMT3B -579G>T genotyping was evaluated using a polymerase chain reaction-restriction fragment length polymorphism technique. Multivariate logistic regression and 95% confidence intervals (CIs) were applied to estimate the UC risk.

RESULTS

We observed that patients with UC exhibited a higher prevalence rate of folate insufficiency (folate levels ≤6 ng/mL) compared with the controls (35.94% and 18.37%, respectively). Furthermore, folate levels were higher in the prevalent UC patients than in the incident UC patients. However, folate insufficiency was similarly associated with a nearly two-fold increase in the risk of UC regardless of the UC patient group. In addition, the frequencies of the variant alleles for DNMT3A and DNMT3B were 0.80 and 0.92, respectively, and no association was observed with UC risk. However, participants with a variant homozygous genotype of DNMT3B -579G>T and folate insufficiency or with high cumulative cigarette smoking exhibited an increased risk of UC.

CONCLUSION

Overall, environmental factors may contribute more significantly to UC carcinogenesis compared with genetic susceptibility. Future studies should investigate other polymorphisms of DNMT3A and DNMT3B to determine genetic susceptibility.

Association between DNA methyltransferases 3B gene polymorphisms and the susceptibility to acute myeloid leukemia in Chinese Han population

DNMT3B plays a crucial role in the generation of aberrant methylation during carcinogenesis. Polymorphisms in the DNMT3B gene may influence the DNA methylation enzymatic activity of DNMT3B, thereby modulating the susceptibility to AML. Thus, we investigated the association between SNPs in the DNMT3Bgene and their haplotypes with the risk of AML in the Chinese Han population. The DNMT3B genotype was determined by HRM in 317 de novo AML patients and 406 healthy control subjects matched for age and gender. Among the 5 SNPs investigated in this study, rs2424913 demonstrated no polymorphisms in the Chinese Han populations, rs1569686 and rs2424908 were significantly associated with AML risk. The GG genotype of rs1569686 was associated with increased AML risk (OR: 5.76; 95%CI: 2.60-12.73; P<0.01) compared with the TT genotype, and individuals with a G allele had a significantly increased risk (OR: 1.89; 95%CI: 1.41-2.52; P<0.01) for AML compared with those harboring a C allele, this polymorphism can predict the risk of AML in a minority of patients. While the CC genotype of rs2424908 appeared to reduce the AML risk (OR: 0.57; 95%CI: 0.36-0.91; P=0.01) compared with the TT genotype, individuals with a C allele were associated with a lower risk (OR: 0.79, 95%CI: 0.64-0.97, P=0.03) for developing AML compared with those harboring a T allele. The other 2 SNPs, rs6087990 and rs6119954, had no significant association with AML risk in the study population. The CGGT, CTAT, TGAT, and CGAT haplotypes of rs6087990, rs1569686, rs6119954, and rs2424908 appeared to significantly increase the AML risk, and the TTGC haplotype appeared to significantly reduce the risk. These results suggest that DNMT3B polymorphisms may contribute to the genetic susceptibility to AML; in particular, the G allele of rs1569686 serves as a risk factor for AML, whereas the C allele of rs2424908 represents a potential protective factor.

Promoter polymorphisms of DNA methyltransferase 3B and risk of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common solid tumors worldwide. Epigenetic changes in gene expression, including DNA methylation and histone modifications, may contribute to the development of HCC. Polymorphisms of the DNA methyltransferase 3B (DNMT3B) gene may affect the activity of this enzyme and increase the susceptibility to several types of cancer, including HCC. To confirm this hypothesis, we investigated the association between single-nucleotide polymorphisms-149C>T (rs2424913) and -579G>T (rs1569686) in the promoter region of DNMT3B and the risk of HCC. DNMT single-nucleotide polymorphisms (SNPs) were genotyped by polymerase chain reaction-restriction fragment length polymorphism in 108 HCC patients and 240 healthy controls matched for age, gender and ethnicity. The DNMT3B-149 TT genotype was not significantly associated with an increased risk of HCC. The frequency of DNMT3B-149C was 0.46% in HCC patients and 1.39% in healthy individuals, whereas the frequency of DNMT3B-579G was 8.33% in HCC patients and 10.42% in healthy individuals. No significant differences were observed in the genotype or allelic distribution between HCC patients and controls. In conclusion, DNMT3B-149C>T and -579G>T polymorphisms are not significantly associated with an increased risk of HCC. These results demonstrated that these particular SNPs may not be used as biomarkers to predict susceptibility to HCC.

Vaccine administration and the development of immune thrombocytopenic purpura in children

The most important reasons cited by the opponents of vaccines are concerns about vaccine safety. Unlike issues such as autism for which no indisputable documentation of direct relationship with vaccine use is available, immune thrombocytopenic purpura (ITP) is an adverse event that can really follow vaccine administration, and may limit vaccine use because little is known about which vaccines it may follow, its real incidence and severity, the risk of chronic disease, or the possibility of recurrences after new doses of the same vaccine. The main aim of this review is to clarify the real importance of thrombocytopenia as an adverse event and discuss how it may interfere with recommended vaccination schedules. The available data clearly indicate that ITP is very rare and the only vaccine for which there is a demonstrated cause-effect relationship is the measles, mumps and rubella (MMR) vaccine that can occur in 1 to 3 children every 100,000 vaccine doses. However, also in this case, the incidence of ITP is significantly lower than that observed during the natural diseases that the vaccine prevents. Consequently, ITP cannot be considered a problem limiting vaccine use except in the case of children suffering from chronic ITP who have to receive MMR vaccine. In these subjects, the risk-benefit ratio of the vaccine should be weighed against the risk of measles in the community.