Somatic STAT5b gain-of-function mutations in early onset nonclonal eosinophilia, urticaria, dermatitis, and diarrhea

To the editor: Somatic, gain-of-function mutations in STAT3 and STAT5 have been described in leukemias and lymphomas[1][1][⇓][2][⇓][3][⇓][4][⇓][5]-[6][6] and, more recently, in CD3-CD4+ T cells from a patient with lymphocytic variant hypereosinophilic syndrome[7][7]; whereas germ line gain-