KLF1 and congenital dyserythropoietic anemia: Haploinsufficiency in KLF1 causes hereditary persistence of fetal hemoglobin (HPFH) (Borg et al., 2010), and a specific mutation in the DNA-binding domain of KLF1 causes type IV congenital dyserythropoietic anemia (CDA) (Iolascon et al., 2013).