Genetics of severe congenital neutropenia as a gateway to personalized therapy.

Severe congenital neutropenias (SCNs) are rare diseases, and to date about 30 subtypes have been described according to their genetic causes. Standard care aims to prevent infections and limit the risk of leukemic transformation; however, several subtypes may have additional organ dysfunction(s), requiring specialized care. Granulocyte colony-stimulating factor and hematopoietic stem cell transplantation are now the bedrock of standard care. Better understanding of SCN mechanisms now offers the possibility of adapted therapy for some entities. An inhibitor of sodium glucose cotransporter, an antidiabetic drug, may attenuate glycogen storage disease type Ib and glucose-6-phosphatase catalytic subunit 3 neutropenias by clearing 1,5-anhydroglucitol, the precursor of the phosphate ester responsible for these SCNs. Chemokine receptor CXCR4 inhibitors contribute to reversing the leukocyte defect in warts, hypoglobulinemia, infections, and myelokathexis syndrome. All these new approaches use oral drugs, which notably improve quality of life. Additionally, improved research into clonal evolution has highlighted some ways to potentially prevent leukemia, such as stimulating somatic genetic rescue, a physiological process that might limit the risk of leukemic transformation.