What is HPFH?
Hereditary persistence of fetal hemoglobin (HPFH) is a benign condition in which significant fetal hemoglobin production continues well into adulthood, disregarding the normal shutoff point after which only adult-type hemoglobin should be produced.
How is HPFH inherited?
About one in a thousand African-Americans have the HPFH carrier (trait) condition, compared with about 1 in 12 who have sickle cell trait. The gene for HPFH is passed down from parent to child just like hair color and eye color.
What causes high HbF?
HbF is elevated in inherited conditions, such as hereditary persistence of HbF, hereditary spherocytosis, and thalassemia. The level of HbF is also increased in acquired states, such as pregnancy, aplastic anemia, thyrotoxicosis, hepatoma, myeloproliferative disorders, or hypoplastic myelodysplastic syndrome.
Do adults have HbF?
The synthesis of fetal hemoglobin (HbF) is normally reduced to very low levels of less than 0.6% of the total hemoglobin in adults. The HbF is restricted to a sub-population of erythrocytes termed ‘F-cells’; 85% of the normal adult population have 0.3% to 4.4% F-cells.
What will happen if HbF persist during adult life?
The persistence of HbF into adult life could be a non-pathogenic condition as in HPFH or be associated with other diseases states. HPFH is a rare benign asymptomatic inherited disorder with persistence of HbF into adult life [1].
What happens if HbF is high?
A baby growing in the womb has high levels of HbF. The level of HbF usually drops to tiny amounts about 6 months after birth. In an adult or child, a higher level of HbF can mean you have a blood disorder. These include thalassemia, myeloid leukemia, and sickle cell anemia.
Why does fetal Haemoglobin need to be replaced?
In foetal life there’s a requirement of foetal hemoglobin to have more affinity towards oxygen than the adult hemoglobin so that it could get sufficient oxygen from the mother. This is achieved by replacing 2β chains with 2 γ chains (HbF).
Which age is fetal hemoglobin HbF still present in the body?
It is produced at around 6 weeks of pregnancy and the levels remain high after birth until the baby is roughly 2–4 months old. Hemoglobin F has a different composition from the adult forms of hemoglobin, which allows it to bind (or attach to) oxygen more strongly.