ABSTRACT
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.
Subject(s)
Anemia, Diamond-Blackfan , Ribosomal Proteins , Humans , Anemia, Diamond-Blackfan/genetics , DNA Copy Number Variations , RNA, Messenger/geneticsSubject(s)
Blood Platelet Disorders , Core Binding Factor Alpha 2 Subunit , Blood Platelet Disorders/diagnosis , Blood Platelet Disorders/genetics , Child , Core Binding Factor Alpha 2 Subunit/genetics , Germ Cells , Humans , Intercellular Signaling Peptides and Proteins/genetics , Mutation , Oncogene Proteins, Fusion/geneticsABSTRACT
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.
