Embden-Meyerhof Pathway Defects

By Evan M. Braunstein, MD, PhD, Instructor of Medicine, Johns Hopkins School of Medicine

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Anemias Caused by Hemolysis
Overview of Hemolytic Anemia
Autoimmune Hemolytic Anemia
Embden-Meyerhof Pathway Defects
Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency
Hemoglobin C Disease
Hemoglobin E Disease
Hemoglobin S-C Disease
Hemoglobin S–Beta-Thalassemia Disease
Hereditary Spherocytosis and Hereditary Elliptocytosis
Paroxysmal Nocturnal Hemoglobinuria (PNH)
Sickle Cell Disease
Stomatocytosis and Anemia Caused by Hypophosphatemia
Thalassemias
Traumatic Hemolytic Anemia

Embden-Meyerhof pathway defects are autosomal recessive RBC metabolic disorders that cause hemolytic anemia.

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 homozygotes. 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 spheres may be present.

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

Treatment

Supportive care
Sometimes splenectomy

There is no specific therapy for these hemolytic anemias. Most patients require no treatment other than supplemental folate 1 mg po once/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.

Last full review/revision January 2017 by Evan M. Braunstein, MD, PhD