Pyruvate kinase deficiency

Definition:

An inherited deficiency in the red blood cell of the enzyme pyruvate kinase. The deficiency is responsible for a form of hemolytic anemia (anemia produced by the destruction of the red blood cell and subsequent release of free hemoglobin into the circulation).

Causes, incidence, and risk factors:

Pyruvate kinase deficiency is transmitted as an autosomal recessive trait. There are many different types of enzymatic defects of the red blood cell that produce hemolytic anemia. However, pyruvate kinase deficiency is important because it is the second most common cause (G-6-PD, glucose-6-phosphatase dehydrogenase is number one) of enzymatic-related hemolytic anemia.

Pyruvate kinase deficiency may produce mild or severe hemolysis and anemia. Problems may first appear in the newborn as prolonged neonatal jaundice and anemia. Older children may be pale (from their anemia) and have intermittent episodes of jaundice.

Although pyruvate kinase deficiency is universal; certain populations, such as the Amish, have a somewhat higher incidence.