Hb Ryazan: An Elongated C-Terminal ß-Chain Due to a New Frameshift Mutation, HBB: c.396delG p.Val133Trpfs*25.

We identified a novel abnormal hemoglobin variant caused by a frameshift mutation at nucleotide position 396 in exon 3 of the ß-globin gene (HBB): NM_000518:c.396delG. This variant causes an emergence of alternative amino acid sequence starting at codon 133 and a new stop codon formed in the 3' untranslated region (3'UTR) of the HBB gene at amino acid position 158. This ß-globin gene variant was identified in a woman with a long history of hemolytic anemia. We named this variant Hb Ryazan after the proband's city of origin.

Splice-site variant in the RPS7 5'-UTR leads to a decrease in the mRNA level and development of Diamond-Blackfan anemia.

Diamond-Blackfan anemia (DBA) is an inherited bone marrow failure syndrome characterized by erythroid aplasia. Pathogenic variants in ribosomal protein (RP) genes, GATA1, TSR2, and EPO, are considered to be the etiology of DBA. Variants in 5'-untranslated regions (UTRs) of these genes are poorly studied and can complicate the variant interpretation. We investigated the functional consequences NM_001011.4:c.-19 + 1G > T variant in the donor splice-site of the RPS7 5'-UTR. This variant was found in a family where two sons with DBA were carriers. Father, who also had this variant, developed myelodysplastic syndrome, which caused his death. Search for candidate causal variants and copy number variations in DBA-associated genes left RPS7 variant as the best candidate. Trio whole exome sequencing analysis revealed no pathogenic variants in other genes. Functional analysis using luciferase expression system revealed that this variant leads to disruption of splicing. Also, a decrease in the levels of mRNA and protein expression was detected. In conclusion, the established consequences of 5'-UTR splice-site variant c.-19 + 1G > T in the RPS7 gene provide evidence that it is likely pathogenic.

De novo TP53 germline activating mutations in two patients with the phenotype mimicking Diamond-Blackfan anemia.

Diamond-Blackfan anemia (DBA) is an inherited bone marrow failure syndrome, associated with mutations in ribosomal protein (RP) genes. Growing data on mutations in non-RP genes in patients with DBA-like phenotype became available over recent years. We describe two patients with the phenotype of DBA (onset of macrocytic anemia within the first year of life, paucity of erythroid precursors in bone marrow) and germline de novo variants in the TP53 gene. Both patients became transfusion independent, probably due to L-leucine therapy. The possible role of TP53 variants should be considered in patients with DBA-like phenotype and no mutations in RP genes.

Efficacy and safety of ruxolitinib in ineffective erythropoiesis suppression as a pretransplantation treatment for pediatric patients with beta-thalassemia major.

BACKGROUND: Ineffective erythropoiesis (IE) is the most prominent feature of transfusion-dependent beta-thalassemia (TDT), which leads to extramedullary hemopoiesis. The rejection rate in allogeneic hematopoietic stem cell transplantation (HSCT) is high in heavily transfused patients with TDT accompanied by prominent IE. Therefore, a pretransplantation treatment bridging to HSCT is often used to reduce allosensitization and IE. Ruxolitinib is a JAK-1/JAK-2 inhibitor and has showed its efficacy in suppressing IE and the immune system. A previously published study on RUX in adult patients with TDT has revealed that this treatment significantly reduces spleen size and is well tolerated. PROCEDURE: Ten patients (5-14 years old) with TDT and an enlarged spleen were enrolled. The dose of ruxolitinib was adjusted for age: for patients <11 years: 40-100 mg/m2 total daily dose and for patients >11 years: 20-30 mg/m2 total daily dose. HSCT was performed in 8 of 10 patients. RESULTS: After the first 3 months of ruxolitinib therapy, spleen volume decreased in 9 of 10 cases by 9.1%-67.5% (M = 35.4%) compared with the initial size (P = 0.003). The adverse events of ruxolitinib (infectious complications, moderate thrombocytopenia, and headache) were successfully managed by reducing the dose. The outcomes of HSCT were favorable in seven of eight cases. CONCLUSION: Ruxolitinib is promising as a short-term pre-HSCT treatment for pediatric patients with TDT and pronounced IE.

Platelet function and blood coagulation system status in childhood essential thrombocythemia.

Childhood essential thrombocythemia (ET) is a rare chronic myeloproliferative disorder. The quality of life of ET patients may decrease as a result of ischemic and hemorrhagic complications of unclear origin. Our goal was to characterize the hemostatic system in children with ET. We genotyped and investigated blood samples from 20 children with ET in a prospective case series study using platelet aggregation, functional flow cytometry (FC) assay and standard clotting assays. Three children had a JAK2V617F mutation, 4 had mutations in CALR and 13 were triple-negative. Myelofibrosis in stage 1-2 was detected in 3 children. Three patients had bleeding episodes and seven had ischemic events. Aggregation in response to collagen, adenosine diphosphate, and ristomycin was decreased in all patients. In FC, significant changes in the whole patient group compared to the healthy children control group were decrease in the resting forward scatter and PAC1 binding (activated GPIIb/IIIa) level. For the activated platelets, dense granules release (by mepacrine), PAC1, and GPIIb/IIIa levels were significantly decreased. GPIb/V/IX, P-selectin, and phosphatidylserine levels manifested only moderate differences. Forward and side scatter changes in response to stimulation (representing shape change) and dense granules release were significantly lower in the 3 patients with bleeding than in the 17 patients without hemorrhage. Activated partial thromboplastin time was slightly prolonged, prothrombin index was slightly shortened and thrombin time was normal, while fibrinogen was mildly decreased in the ET patients. It could be concluded that the observed platelet function defects could be related to bleeding in ET, and be potentially used as a marker.