Defective Synthesis of an Unstable Haemoglobin: Haemoglobin Koln (β 98 Val‐Met)

S ummary . The in vitro synthesis of haemoglobin A and the unstable haemoglobin, haemoglobin Köln, has been studied using reticulocytes from a patient heterozygous for these two haemoglobins. The proportions of the two haemoglobins synthesized were: 80% haemoglobin A and 20% haemoglobin Köln. The small amount of haemoglobin Köln synthesized has been found to be due to a deficiency in the synthesis of β Koln ‐chains. The deficiency of β Koln ‐chains results in an excess production of α‐chains by the reticulocytes, which can be detected as a free α‐chain pool. The excess α‐chains are available to combine with β A ‐chains to synthesize haemoglobin A. The overall result is a preferential synthesis of haemoglobin A over haemoglobin Köln. The deficiency in the synthesis of the unstable haemoglobin probably explains the comparatively mild degree of haemolysis found in haemoglobin Köln disease.