Thalassemia

Circular RNA circ-0008102 has previously been found dysregulated in β-thalassemia (β-thal) in circRNAs microarray (GSE196682 and GSE241141). Our study is aimed at identifying whether circ-0008102 could be a novel biomarker in β-thal. The peripheral blood of pediatric β-thal patients with (n = 39) or without (n = 20) blood transfusion and healthy controls (n = 30) was selected. qRT-PCR, ROC curve analysis, Spearman correlation analysis, and FISH were used to analyze clinical value of circ-0008102. qRT-PCR confirmed that circ-0008102 expression in pediatric β-thal patients without blood transfusion was significantly higher. ROC curves analysis showed that the AUC of circ-0008102 for differentiating patients without blood transfusion from patients with blood transfusion and healthy controls with an AUC of 0.733 and 0.711. Furthermore, circ-0008102 expression was positively correlated with the levels of RBC, HbF, β-globin, and γ-globin mRNA, but was negatively corrected with the levels of HbA and Cr. circ-0008102 was mainly located in the cytoplasm. circ-0008102 could induce the activation of γ-globin and negatively regulate the expression of the five highest-ranking candidate miRNAs (miR-372-3p, miR-329-5p, miR-198, miR-152-5p, and miR-627-3p) in K562 cells.ConclusionWe demonstrate that peripheral blood upregulated circ-0008102 may serve as a novel clinical biomarker for pediatric β-thal without blood transfusion.What is known• CircRNAs are known to be involved in various human diseases, and several circRNAs are regarded as a class of promising blood-based biomarkers for detection of β-thal. • CircRNAs exert biological functions by epigenetic modification and gene expression regulation, and dysregulated circRNAs in β-thal might be involved in the induction of HbF in β-thal.What is new• Peripheral blood circ-0008102 maybe serve as a novel clinical biomarker for detection of pediatric β-thal without blood transfusion. • Circ-0008102 participates in the pathogenesis of β-thal through regulating γ-globin expression, and negatively regulates the expression of miR-372-3p, miR-329-5p, miR-198, miR-152-5p and miR-627-3p.

IntroductionThe increase in the number of patients with hemoglobinopathies in Europe in recent decades highlights the need for more detailed epidemiological information in Spain. To fulfil this need, the Spanish Society of Pediatric Hematology and Oncology (SEHOP) sponsored the creation of a national registry of hemoglobinopathies known as REHem-AR (Spanish Registry of Hemoglobinopathies and Rare Anemias). Data from the transfusion-dependent (TDT) and non-transfusion-dependent (NTDT) β-thalassemia cohorts are described and analyzed.MethodsWe performed an observational, multicenter, and ambispective study, which included patients of any age with TDT and NTDT, registered up to December 31, 2021.ResultsAmong the 1741 patients included, 168 cases of thalassemia were identified (103 TDT and 65 NTDT-patients). Survival at 18 years was 93% for TDT and 100% for NTDT. Regarding management, 80 patients with TDT (77.7%) and 23 patients with NTDT (35.4%) started chelation treatment during follow-up, with deferasirox being the most widely used. A total of 76 patients within the TDT cohort presented at least 1 complication (73.8%), the most frequent being hemosiderosis and osteopenia-osteoporosis. Comparison of both cohorts revealed significant differences in the diagnosis of hepatic hemosiderosis (p = 0.00024), although these were not observed in the case of cardiac iron overload (p = 0.27).DiscussionOur registry enabled us to describe the management of β thalassemia in Spain and to analyze the morbidity and mortality of the cohorts of patients with TDT and NTDT. Complications related to iron overload in TDT and NTDT account for most of the morbidity and mortality of the disease, which is associated with a considerable social, psychological, and economic impact, although cardiac, osteopathy and endocrinological complications requiring more attention. The convenience and simplicity of online registries make it possible to homogenize variables and periodically update data, thus providing valuable information on these diseases.

Despite the well-documented mutation spectra of β-thalassemia, the genetic variants and haplotypes of globin gene clusters modulating its clinical heterogeneity remain incompletely illustrated. Here, a targeted long-read sequencing (T-LRS) is demonstrated to capture 20 genes/loci in 1,020 β-thalassemia patients. This panel permits not only identification of thalassemia mutations at 100% of sensitivity and specificity, but also detection of rare structural variants (SVs) and single nucleotide variants (SNVs) in modifier genes/loci. The highly homologous regions of α-/β-globin gene clusters are then phased and 3 novel haplotypes in HBG1/HBG2 region are reported in this population of β-thalassemia patients. Furthermore, one of the haplotypes is associated with ameliorated symptoms of β-thalassemia. Similarly, 5 major haplotypes are identified in HBA1/HBA2 homologous region while one of them is found highly linked with deletional α-thalassemia mutations. Finally, rare mutations in erythroid transcription factors in DNMT1 and KLF1 associated with increased expression of fetal hemoglobin and reduced transfusion dependencies are identified. This study presents the largest T-LRS study for β-thalassemia patients to date, facilitating precise clinical diagnosis and haplotype phasing of globin gene clusters.

β-thalassemia is a recessively inherited blood disorder affecting millions worldwide. Pharmacological induction of fetal hemoglobin (HbF) is an effective therapeutic strategy, yet existing DNA methyltransferase (DNMT) inhibitors, although effective HbF inducers, currently are not approved for β-thalassemia treatment. Here, we report that DMT207, a novel non-nucleoside DNMT1 inhibitor, robustly reactivates HbF in HUDEP-2 cells and adult primary erythroblasts with minimal toxicity. In a mouse model of β-thalassemia, DMT207 effectively elevates the levels of mouse fetal- and embryonic-type hemoglobin, promotes the maturation of erythroid cells, and alleviates the splenomegaly. Further multi-omics analyses expose γ-globin as one of the most sensitive genes with promoter demethylation and transcriptional activation following DMT207 treatment. Mechanistically, DMT207 traps DNMT1 into a catalytically inactive conformation and concurrently enhances its interaction with UHRF1, which partially contributes to DNMT1 degradation. These findings highlight the therapeutic potential of DMT207 for β-thalassemia and support its further preclinical development.