Hb S(C)‐β+‐thalassaemia: different mutations are associated with different levels of normal Hb A

Publisher Website
Google Scholar
Abstract
Analysis of amplified DNA through hybridization with 32P‐labelled synthetic oligonucleotide probes has provided data about the molecular abnormality for β‐thalassaemic globin genes present in 32 Black and eight Mediterranean patients with Hb S(C)‐β+‐thalassaemia. The patients were categorized according to these β‐thalassaemia mutations, and average haematological and haemoglobin composition data were compared for each of four different groups. Twenty‐eight Black patients had the ‐29 AG substitution and four had the ‐88 CT substitution; all had mild disease with comparable haematology and an average Hb A level of 20%. Six Mediterranean patients had the IVS‐1, 110 GA mutation; their haematological data were nearly the same as that for the Black patients except for a lower Hb A value of 11%. Two Turkish patients with the IVS‐2, 745 CG mutation were more severely affected with mild sickling disease and low Hb A levels of 5%. Hb F levels varied greatly because of age differences; high Gγ values were observed only in patients with a β‐thalassaemia chromosome having an Xmn I site 5’to Gγ.The data readily explain the variability in Hb A level that has been repeatedly noted in patients with Hb S(C)‐β+‐thalassaemia.