Hereditary persistence of fetal hemoglobin

Hereditary persistence of fetal hemoglobin, often shortened to HPFH, is a benign condition in which production of fetal hemoglobin (hemoglobin F) carries on well into adulthood, instead of switching off after infancy so that only adult-type hemoglobin is made. It causes no symptoms and is usually noticed only when a person is screened for another hemoglobin disorder. It can result from mutations in the beta globin gene cluster or in the promoter region of the gamma globin gene, and fetal hemoglobin levels are also shaped by variants in the BCL11A gene and in the MYB gene enhancer. The share of fetal hemoglobin ranges from under 1 percent to about 30 percent of the total, and can reach 100 percent in people homozygous for delta-beta thalassemia. Diagnosis is made by finding a marked rise in fetal hemoglobin. Because fetal hemoglobin inhibits the polymerization of hemoglobin S, the condition makes sickle cell disease less severe, and it may ease some thalassemias. It is selected for in populations where these disorders are common, as in areas where malaria is endemic, and has been found in people of African and Greek descent.