Hereditary persistence of fetal hemoglobin
|Hereditary persistence of fetal hemoglobin|
|Classification and external resources|
Hereditary persistence of fetal hemoglobin (HPFH, BrE: Hereditary persistence of foetal haemoglobin) is a benign condition in which significant fetal hemoglobin (hemoglobin F) production continues well into adulthood, disregarding the normal shutoff point after which only adult-type hemoglobin should be produced.
This is usually caused by mutations in the β-globin gene cluster. The percentage of incorrect expression might be as low as 10-15% or as high as 100% of the total hemoglobin, usually higher in homozygotes than in heterozygotes.
HPFH may alleviate the severity of certain hemoglobinopathies and thalassemias, and is selected for in populations with a high prevalence of these conditions (which in turn are often selected for in areas where malaria is endemic). Thus, it has been found to affect Americans of African and Greek descent.
The condition is usually asymptomatic, and is only noticed when screening for other hemoglobin disorders.
Benefit to persons with sickle cell disease
In persons with sickle cell disease, high levels of fetal hemoglobin as found in a newborn or as found abnormally in persons with hereditary persistence of fetal hemoglobin, the HbF causes the sickle cell disease to be less severe. In essence the HbF inhibits polymerization of HbS. A similar mechanism occurs with persons who have sickle cell trait. Approximately 40% of the hemoglobin is in the HbS form while the rest is in normal HbA form. The HbA form interferes with HbS polymerization.
- Friedman S, Schwartz E (January 1976). "Hereditary persistence of foetal haemoglobin with beta-chain synthesis in cis position (Ggamma-beta+-HPFH) in a negro family". Nature 259 (5539): 138–40. doi:10.1038/259138a0. PMID 1246351.
- Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009-05-28). Robbins and Cotran Pathologic Basis of Disease, Professional Edition: Expert Consult - Online (Robbins Pathology) (Kindle Locations 33411-33412). Elsevier Health. Kindle Edition.