Identification of an erythrocyte pyruvate kinase variant in a family from Latium with non-spherocytic congenital haemolytic anaemia.

Erythrocyte PK deficiency was detected in a family from Latium in Italy. This PK variant is characterized by normal or increased activity immediately after blood collection, instability to storage, to heat and to urea. Only in the propositus the mutant enzyme exhibited an increased Michaelis constant for PEP, slightly increased inhibition by ATP and an altered optimum pH value. The kinetic anomaly was only partially corrected by activation with F-1, 6-DP and by addition of 2-ME. From these results it can be concluded that in the family observed two distinct erythrocyte PK alterations were demonstrable: instability in the propositus and his father; low affinity for PEP and altered optimum pH value only in the propositus.