Chronic Haemolytic Anaemia in Two Patients Heterozygous for Erythrocyte Pyruvate Kinase Deficiency

Abstract

Two patients with mild chronic hemolytic anemia, a mother and her son, were heterozygous for erythrocyte pyruvate kinase [PK] deficiency. In the red blood cells, the enzymatic activity was reduced by about 50% and the residual PK had normal kinetic properties, stability and electrofocusing pattern. The PK antigen concentration was also decreased by half, so that the ratio of the enzymatic activity to the immunological reactivity (i.e., the molecular specific activity) was normal. In the son''s liver PK enzymatic activity was slightly reduced and, above all, an abnormal active form, more anodic than normal PK, was detected by electrofocusing. The propositus''s liver PK was also slightly thermo-unstable. The patients were probably heterozygous for an unstable PK variant which was found in liver, nucleated tissue actively synthesizing proteins, but which disappeared from the erythrocytes because of its unstability.