Research ArticleMYELODYSPLASTIC SYNDROME

A variant erythroferrone disrupts iron homeostasis in SF3B1-mutated myelodysplastic syndrome

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Science Translational Medicine  10 Jul 2019:
Vol. 11, Issue 500, eaav5467
DOI: 10.1126/scitranslmed.aav5467

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Myelodysplastic syndromes are clonal disorders of hematopoiesis with a variety of manifestations and potential complications. One category of myelodysplastic syndromes, those associated with ring sideroblasts, is known for causing iron overload even in the absence of transfusions, but the reasons for this are unclear. Bondu et al. discovered that a variant form of erythroferrone, a hormone that helps regulate bone marrow function, is produced in this disorder and results in deregulation of iron loading through suppression of the hormone hepcidin. Moreover, the variant erythroferrone is not present in healthy bone marrow cells, indicating its potential utility as a biomarker of clonal hematopoiesis.

Abstract

Myelodysplastic syndromes (MDS) with ring sideroblasts are hematopoietic stem cell disorders with erythroid dysplasia and mutations in the SF3B1 splicing factor gene. Patients with MDS with SF3B1 mutations often accumulate excessive tissue iron, even in the absence of transfusions, but the mechanisms that are responsible for their parenchymal iron overload are unknown. Body iron content, tissue distribution, and the supply of iron for erythropoiesis are controlled by the hormone hepcidin, which is regulated by erythroblasts through secretion of the erythroid hormone erythroferrone (ERFE). Here, we identified an alternative ERFE transcript in patients with MDS with the SF3B1 mutation. Induction of this ERFE transcript in primary SF3B1-mutated bone marrow erythroblasts generated a variant protein that maintained the capacity to suppress hepcidin transcription. Plasma concentrations of ERFE were higher in patients with MDS with an SF3B1 gene mutation than in patients with SF3B1 wild-type MDS. Thus, hepcidin suppression by a variant ERFE is likely responsible for the increased iron loading in patients with SF3B1-mutated MDS, suggesting that ERFE could be targeted to prevent iron-mediated toxicity. The expression of the variant ERFE transcript that was restricted to SF3B1-mutated erythroblasts decreased in lenalidomide-responsive anemic patients, identifying variant ERFE as a specific biomarker of clonal erythropoiesis.

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