DefinitionPyruvate kinase deficiency is an inherited lack of the enzyme pyruvate kinase, which is used by red blood cells. Without this enzyme, red blood cells break down too easily, resulting in low levels of these cells (hemolytic anemia).Causes, incidence, and risk factorsPyruvate kinase deficiency is passed down as an autosomal recessive trait. A child must receive the non-working gene from both parents to develop the disorder.There are many different types of enzyme-related defects of the red blood cell that can cause hemolytic anemia. Pyruvate kinase deficiency is the second most common cause, after G-6-PD deficiency.Pyruvate kinase deficiency is found in people of all ethnic backgrounds. However, certain populations, such as the Amish, are somewhat more likely to develop the conditi