  right|thumb|distribution of red blood cell abnormalities worldwide pyruvate kinase deficiency, also called erythrocyte pyruvate kinase deficiency, is an inherited metabolic disorder of the enzyme pyruvate kinase which affects the survival of red blood cells and causes them to deform into echinocytes ("burr cells") on peripheral blood smears. both autosomal dominant and recessive inheritance have been observed with the disorder; classically, and more commonly, the inheritance is autosomal recessive. pyruvate kinase deficiency is the second most common cause of enzyme-deficient hemolytic anemia, following g6pd deficiency. ==causes== a variety of mutations can lead to lowered production, activity, or stability of pyruvate kinase, an enzyme essential to glycolysis. a total lack of this enzyme's activity will be lethal[citation needed]. ==pathophysiology== erythrocytes manufacture atp through glycolysis. a deficiency in pyruvate kinase, the enzyme that potentiates the last step of glycolysis (phosphoenolpyruvate converted to pyruvate), results in red blood cells (rbcs) with decreased energy. the events leading to hemolysis are still not well understood, but it seems that the lack of atp impairs the na+/k+-atpase and other atp-dependent processes, leading to a cellular loss of k+ and water and an intracellular accumulation of na+. this cellular swelling is comparable to ischemic changes in which cells denied of o2 suffer from an atp deficiency. this swelling causes rigidity of the rbc and eventually splenic hemolysis from an inability to distort through splenic sinusoids. partial splenectomies are sometimes performed as a
Hereditary_hemolytic_anemias Inborn_errors_of_carbohydrate_metabolism