Hereditary persistence of fetal hemoglobin

Overview
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.

Causes
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.

Epidemiology
HPFH may alleviate the severity of certain hemaglobinopathies 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 black people, as well as Greeks.

Presentation
The condition is usually asymptomatic, and is only noticed when screening for other hemoglobin disorders.