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Glycolytic Pathway Defects

(Embden-Meyerhof Pathway Defects)

By

Evan M. Braunstein

, MD, PhD, Johns Hopkins University School of Medicine

Last full review/revision Sep 2020
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Glycolytic pathway defects are autosomal recessive red blood cell metabolic disorders that cause hemolytic anemia.

The glycolytic pathway is one of the body's important metabolic pathways. It involves a sequence of enzymatic reactions that break down glucose (glycolysis) into pyruvate, creating the energy sources adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide (NADH). Various inherited defects in enzymes of the pathway may occur.

The most common defect is

  • Pyruvate kinase deficiency

Other defects that cause hemolytic anemia include deficiencies of

  • Erythrocyte hexokinase

  • Glucose phosphate isomerase

  • Phosphofructokinase

In all of these pathway defects, hemolytic anemia occurs only in patients who are homozygous. The exact mechanism of hemolysis is unknown.

Symptoms are related to the degree of anemia and may include jaundice and splenomegaly. Spherocytes are absent, but small numbers of irregularly shaped cells (echinocytes) may be present.

In general, assays of ATP and diphosphoglycerate help identify any metabolic defect and localize the defective sites for further analysis.

Treatment of Glycolytic Pathway Defects

  • Folic acid during acute hemolysis

  • Transfusions if needed

  • Sometimes splenectomy

There is no specific therapy for hemolytic anemias caused by glycolytic pathway defects. Most patients require no treatment other than supplemental folic acid 1 mg orally once a day during acute hemolysis. In severe cases, patients may be transfusion dependent in which case, splenectomy may be done. Hemolysis and anemia persist after splenectomy, although some improvement may occur, particularly in patients with pyruvate kinase deficiency.

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