Wake-up Sleepy Gene: Reactivating Fetal Globin for β-Hemoglobinopathies.

Disorders in hemoglobin (hemoglobinopathies) were the first monogenic diseases to be characterized and remain among the most common and best understood genetic conditions. Moreover, the study of the β-globin locus provides a textbook example of developmental gene regulation. The fetal γ-globin genes (HBG1/HBG2) are ordinarily silenced around birth, whereupon their expression is replaced by the adult β-globin genes (HBB primarily and HBD). Over 50 years ago it was recognized that mutations that cause lifelong persistence of fetal γ-globin expression ameliorate the debilitating effects of mutations in β-globin. Since then, research has focused on therapeutically reactivating the fetal γ-globin genes. Here, we summarize recent discoveries, focusing on the influence of genome editing technologies, including CRISPR-Cas9, and emerging gene therapy approaches.