Haemoglobin Belfast 15 (A12) tryptophan leading to arginine: a new unstable haemoglobin variant.

A new unstable haemoglobin, alpha(2)beta(2)15 Trp--> Arg (Hb Belfast), with increased oxygen affinity has been found during the routine investigation of a long-stay psychiatric patient. It seemed to cause little haematological disorder. The reticulocytes synthesized normal and abnormal beta-chains at the same rate but in the circulating blood Hb Belfast amounted to only 27.5% of the total haemoglobin.