Erythraemia due to Haemoglobin San Diego

S ummary . A 63‐year‐old man with erythraemia was found to have a high affinity haemoglobin which was subsequently identified as Hb San Diego β 109 (G11) Val→Met, recently described in a Filipino family (Nute et al , 1974). The oxygen affinity of the haemolysates was increased approximately two‐fold at pH values between 6.04 and 7.90. The n value was nearly normal (2.5–2.9) in the upper range of saturation (70–95% oxygenation) but was somewhat diminished (1.9–2.1) below this range. In vitro biosynthesis of globin by reticulocytes showed that there was balanced synthesis of α and β chains (α:β ratio = 1).