Cookies on this website
We use cookies to ensure that we give you the best experience on our website. If you click 'Continue' we'll assume that you are happy to receive all cookies and you won't see this message again. Click 'Find out more' for information on how to change your cookie settings.

ine patients have been observed with homozygous beta thalassaemia in each of whom one parent has a normal level of Hb A2. On the basis of clinical, haematological and globin chain synthesis studies these families have been divided into two groups. Group 1 (six families). Heterozygotes for normal Hb A2-beta thalassaemia in this group showed minimal red cell abnormalities, normal osmotic fragility but imbalanced globin chain synthesis (alpha/beta=1.6), and appear to correspond to previous descriptions of 'silent' beta thalassaemia. Double heterozygotes with high Hb A2-beta thalassaemia have a clinical picture of mild beta thalassaemia intermedia characterized by relatively low levels of Hb F (less than 20%) and gamma chain synthesis. Group 2 (three families). beta Thalassaemia heterozygotes with normal HbA2 levels in this group showed more marked red cell abnormalities, decreased osmotic fragility and more imbalanced globin chain synthesis (alpha/beta=2.5) than those in group I. Double heterozygotes with high Hb A2-beta thalassaemia are more severely affected and are transfusion dependent. Haemoglobin F and gamma chain synthesis are high in these cases. The frequency of normal Hb A2-beta thalassaemia in Greece may be as high as 10% of all beta thalassaemia genes and this poses a significant problem for genetic counselling. Various molecular mechanisms are discussed which could account for the heterogeneity within these disorders.

Type

Journal article

Journal

Br J Haematol

Volume

42

Pages

109 - 23