Delayed fetal hemoglobin switching in subjects with KLF1 gene mutation.

Variations at the KLF1 gene have been associated with a series of human erythroid phenotypes including the In-(Lu) phenotype, hereditary persistence of fetal hemoglobin, congenital dyserythropoietic anemia, borderline HbA(2) and increased red blood cell protoporphyrin. Natural mutations have shown that KLF1 regulates gamma globin gene expression and its role in the switching from fetal to adult globin expression has been suggested by experimental studies. In this paper we report that subjects with S270X KLF1 mutations show a decrease of HbF levels with increasing age, supporting in vivo the role of KLF1 in hemoglobin switching in humans.