Four new pyruvate kinase (PK) variants and a classical PK deficiency

Four new red-cell pyruvate kinase (PK) variants are presented along with one case of so-called classical type PK deficiency. PK 'Tokyo II' had a low activity, Km (PEP) and Vmax, but a normal urea stability and only slight deviation from normal in neutralization tests by antiserum. It had a normal nucleotide specificity, abnormal electrophoretic mobility (fast moving) and the variant was associated with a mild hemolytic anaemia. PK 'Maebashi' had a low activity, high Km (PEP), low Vmax, urea instability, decreased reactivity to antiserum, normal electrophoretic mobility, normal nucleotide specificity and was associated with a moderate haemolytic anaemia. PK 'Tsukiji' had low activity, high Km (PEP), markedly high Vmax, urea instability, decreased reactivity to antiserum, abnormal electrophoretic mobility (fast moving) and grossly abnormal nucleotide specificity especially abnormal behaviour to ADP. The haemolytic process in this case was moderate to severe. PK 'Ube' was electrophoretically abnormal (fast moving) but otherwise had normal characteristics and the propositus was healthy and not anaemic. PK 'Ube' was found by electrophoretic screening for genetic PK polymorphism. In the classical type PK deficiency, the usual red-cell PK (PK-R1 and PK-R2) was not demonstrable by electrophoresis but instead M2-type PK was present, presumably by compensatory process. Kinetic studies confirmed that the patient's red-cell PK consisted of M2-type PK. This patient had a severe haemolytic anaemia.