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

Erythrocyte pyruvate kinase deficiency: 11 new cases

Eleven new cases of red cell pyruvate kinase (PK) deficiency with congenital haemolytic disease from 10 unrelated Italian families were characterized using the methods recommended by the International Committee for Standardization in Haematology (ICSH). All patients were double heterozygotes for the PK gene. The 10 variants were designated PK 'Lecce,' 'Parma,' 'Verona,' 'Milano,' 'Soresina,' 'Macerata,' 'Sassari,' 'Genova,' 'Mantova' and 'Brescia.' PK 'Sassari' was associated with glucose-6-phosphate dehydrogenase deficiency in two siblings. All mutants displayed multiple biochemical abnormalities except for PK 'Lecce' that only showed decreased red cell PK activity. No relation was found between the severity of anaemia and either the residual PK activity or specific biochemical enzyme abnormalities. Increased serum ferritin levels were detected in most of the patients, suggesting the need for systematically monitoring iron status in this disease.

Seven pyruvate kinase variants characterized by the ICSH recommended methods

Seven new red-cell pyruvate kinase (PK) variants were characterized by the methods recently recommended by the International Committee for Stanardization in Haematology. The cases were all true homozygote as evidenced by consanguineous marriages of the parents; all are Japanese. These variants were designated as PK Tokyo, PK Nagasaki, PK Sapporo, PK Maebashi, PK Itabashi, PK Fukushima and PK Aizu, respectively. Low substrate affinity (high K0.5S for phosphoenolpyruvate) and thermal instability appear to play major roles in causing defective enzyme function, resulting in chronic haemolytic anaemia. Product inhibition of PK by ATP may also play an additional role in causing haemolysis in more than half the cases.

Pyruvate kinase variants characterized by the methods recommended by the International Committee for Standardization in Haematology

Seven new pyruvate kinase (PK) variants were characterized by the recently established recommended methods by the International Committee for Standardization in Haematology (ICSH). The seven cases were all true homozygotes as evidenced by consanguineous marriages of the parents. All of them were Japanese. These variants were designated PK Tokyo, Nagasaki, Sapporo, Maebashi, Itabashi, Fukushima, and Aizu. Low substrate affinity for phosphoenolpyruvate and thermal instability seem to play a major role in causing clinical manifestation of chronic hemolysis. Product inhibition of PK by ATP may also play an additional role in some cases.