Loss-of-function zinc finger mutation in the EGLN1 gene associated with erythrocytosis

TO THE EDITOR: Mutations in the EGLN1 (also known as PHD2 ) gene are associated with erythrocytosis.[1][1] The encoded protein, PHD2, is a central cellular oxygen sensor that hydroxylates the α subunit of the hypoxia inducible factor (HIF) transcription factor complex, marking it for degradation.[