The β-thalassaemias: An overview

β-Thalassaemia is the most common genetic disorder in Mediterranean populations. As of today, the number of mutations known to cause β-globin chains of Hb A, and 50 cause a variable decrease (Bβ⁺). Clinical severity is determined by the type of mutation and co-inheritance of α-thalassaemia and high Hb F production. Mild β⁺ mutations and increased γ chain (Hb F) production often lead to a β-thalassaemia intermedia. 'Silent β-thalassaemia' represents the mildest form of the disease, which in the simple heterozygote, is often not detectable by routine diagnostic methods. At the other end of the spectrum is the 'severe heterozygous β-thalassaemia' or 'inclusion body β-thalassaemia', characterized by highly unstable β-globin chains with altered carboxytermini, and autosomal dominant inheritance.