Haemoglobin Q India (alpha 64(E13) aspartic acid histidine) associated with beta-thalassemia observed in three Sindhi families.

Abstract

Haemoglobin Q was first reported in a Chinese man in whom it was associated with Hb H disease, and therefore with a-thalassaemia (Vella et al, 1958). It has been discovered in other people, mostly in south-east Asia, and these reports have been summarized by Sagnet et al (1968). Al- though it was known that Hb Q was an a-chain abnormal haemoglobin with a mutation in the tryptic peptide No. 9 of the a-chain (aTpIX) which comprises residues 62-90 of the 141 residues of the a-chain, the exact amino-acid substitution had re- mained undetermined. However, 2 haemoglobins Q were characterized by Lorkin et al in 1970. One type came from both a Chinese and a Thai family (in which it was associated with a-thalassaemia) and had the substitution a74 Asp->His, and the other, a75 Asp--His, came from Iran. Independently, the first variant, described as Hb G Taichung, was found in a Chinese by Blackwell and Liu (1970), and in a Thai, where it was again associated with a-thalassaemia, as Hb Mahidol, by Pootrakul and Dixon (1970). In India only a few cases of Hb H disease have been found, indicating that a-thalas- saemia is probably rare; f-thalassaemia is however quite common (Chatterjea, 1966; Chouhan, Sharma, and Parekh, 1970).