Hereditary persistance of foetal haemoglobin

Haemoglobin F (Hb F) is present in foetal and neonate red cells, and normally decreases progressively after birth until levels under 1% at the age of 1 to 2 years are reached. In a group of disorders called hereditary persistence of foetal haemoglobin (HPFH), expression of the gamma-globin gene (component of Hb F) persists at high levels in adult red cells. Deletion as well as nondeletion (point mutation) types of HPFH have been identified. Patient may, or may not, have microcytosis usually without anaemia. Homozygous individuals have up to 100% Hb F, while heterozygotes have 20-40%. HPFH has similarities with thalassaemia, but has usually no clinical consequences. Actually, the decreased or absent synthesis of beta or delta adult globin chains is compensated by the presence of large amounts of Hb F.

Synonym: HPFH