A family case of pyruvate kinase variant, PK 'Nichinan'.

A case of congenital hemolytic anemia caused by pyruvate kinase (PK) deficiency variant designated PK 'Nichinan' is presented. A 29-old patient with a history of anemia and hepatosplenomegaly had an episode of aplastic crisis associated with fever, abdominal symptoms and worsening hepatosplenomegaly. Study of the family members revealed that his mother and two of three siblings showed decreased PK activity whereas his father showed normal PK activity with a normal level of glycolytic intermediates. The patient was assumed to be a double heterozygote with two separate mutant genes from the parents despite the apparent normality of his father's erythrocyte PK.