Volume 131, Issue 20



May 17, 2018 – Welcome to “This Week in Blood,” a weekly snapshot of the hottest studies from each week’s issue of Blood, the official journal of the American Society of Hematology (ASH), hand-picked by Blood Editor-in-Chief Bob Löwenberg, MD, PhD, and Deputy Editor Nancy Berliner, MD.

Cover Figure: Role of Ezh2 in the vascular niche. See the article by Neo et al.

Clinical spectrum of pyruvate kinase deficiency: data from the Pyruvate Kinase Deficiency Natural History Study
In this plenary paper, Grace and colleagues provide a comprehensive overview of the clinical spectrum of pyruvate kinase deficiency (PKD). This retrospective study of 254 patients elucidates the broad range of the clinical severity of PKD and characterizes the complex genotype-phenotype relationship of this rare disease, providing important entry points for further study.

Cell-extrinsic hematopoietic impact of Ezh2 inactivation in fetal liver endothelial cells
In an elegant murine genetic study, Neo et al demonstrate that inactivation of Ezh2 in fetal hematopoietic stem cells has minimal impact on hematopoiesis, but Ezh2 inactivation in endothelial cells leads to severe anemia through inhibition of membrane expression of Kit ligand. This confirms that Ezh2 regulates hematopoiesis through cell-extrinsic modulation of the vascular niche.

PDGFRB mutation and tyrosine kinase inhibitor resistance in Ph-like acute lymphoblastic leukemia
In this month’s CME article, Philadelphia chromosome–like acute lymphoblastic leukemia (Ph-like ALL) often responds to tyrosine kinase inhibitors (TKIs) but may develop resistance. Through an in-depth genetic analysis of a case of TKI-resistant Ph-like ALL, Zhang et al identify an oncogenic PPDGFR fusion gene that is suppressed by TKIs, with clonal evolution and emergence of a somatically mutated PDGFR allele that confers resistance.

Tolerogenic properties of the Fc portion of IgG and its relevance to the treatment and management of hemophilia
Blumberg and Lillicrap review the underappreciated ability of the crystallizable fragment (Fc) portion of immunoglobulin G (IgG) to induce tolerance to attached molecules and discuss how this could contribute to low immunogenicity of Fc-fusion recombinant factors for hemophilia.

Biomarkers for posttransplantation outcomes
In a Perspective, Paczesny discusses the range of potential informative biomarkers for predicting posttransplantation outcomes that can be assessed through genomics, transcriptomics, proteomics, and cytomics.

How I treat the postthrombotic syndrome
Rabinovich and Kahn use 2 cases as the basis for a discussion of the risk factors and potential interventions for postthrombotic syndrome.



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