Fortnightly review: The thalassaemiasBMJ 1997; 314 doi: https://doi.org/10.1136/bmj.314.7095.1675 (Published 07 June 1997) Cite this as: BMJ 1997;314:1675
- D J Weatherall, professora
- a Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DU
The thalassaemias, the commonest monogenic diseases, are a family of inherited disorders of haemoglobin synthesis characterised by a reduced output of one or other of the globin chains of adult haemoglobin. They are likely to pose an increasing health problem for many developing countries during the early part of the new millennium.1 This review focuses mainly on their control and management, a subject of increasing importance not only for parts of the world in which the disease is particularly common but for any country which has an immigrant population from these regions.
This article is based on a literature survey of the field since 1980, recent monographs2 3 and review series4 that cover the thalassaemia field, and a detailed appraisal of the statistical analysis of the validity of screening techniques.5 Various aspects of the disease were discussed at the 26th congress of the International Society of Haematology held in Singapore in August 1996, the published proceedings of which provide a valuable, up to the minute account of some aspects of current practice.6 7 8 9 10
Genetic control of haemoglobin
All the human haemoglobins consist of two different pairs of globin chains combined with haem, the iron containing moiety that binds oxygen. Embryonic haemoglobin has ζ chains and γ chains (ζ2γ2); fetal haemoglobin, the synthesis of which continues throughout fetal life and declines after birth, has α chains and γ chains (α2γ2), and in adults there is a major component called haemoglobin A (α2ß2) and a minor fraction, haemoglobin A2 (α2δ2). The α-like chains–that is, ζ and α–are controlled by genes at the tip of the short arm of chromosome 16 and the genes that control the γ, γ, ß, and δ chains form a linked cluster on chromosome 11 in the order γ, γ, δ, ß. Both the …