Glycolytic Pathway Defects
(Embden-Meyerhof Pathway Defects)
(See also Overview of 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
Other defects that cause hemolytic anemia include deficiencies of
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.
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.