Defects in the synthesis of human haemoglobin

Abstract

The work described is concerned with the biosynthesis of haemoglobin in human reticulicytes and bone marrow cells with particular reference to abnormal haemoglobins. The work in abnormal haemoglobins was supported by structural studies and involved a - and ß - chain variants, some of the latter being unstable. In some of the individuals with α or ß - chain variants, as well as in a number of subjects with β- thalassaemia, the estimation of the free α - chian pool was carried out. Using the same methodology, an attempt was made to detect chain fragments in the latter group of subjects. In the α - chian variants, attention was paid to the different proportions of the same α - chian abnormal haemoglobin in different individuals. Notably so in the case of haemoglobin G Philadelphia. The results supported the interpretation that here are four α - chian genes and that the α - G Philadelphia gene may occur together with threee, two or one normal α - chian genes respectively, the number of normal α - chian genes being potentially decreased by α - thalassaemia. With ß - chain variants a number of low proportion abnormal haemoglobins in the blood was studied. The globin chain synthesis pattern in the reticulocytes was compared with the haemoglobin composition in the mature red cells and the clinical condition of the subjects. Structural changes in haemoglobin were related to the rate of its synthesis. In some instances, both the synthesised amount of the variant was low as well as its proportion in the mature red cells. In others, notably haemoglobin E and Haemoglobin newcastle, the synthesis rate of the variant was normal but its proportion in the circulating red cells was low. Possible molecular mechanisms are either instability of the variant ß - chain of defective association into functioning polymer.