Hereditary pyropoikilocytosis (HPP) is an autosomal recessive disorder of the red blood cell (RBC) membrane that is clinically related to, and is considered a subtype of, hereditary elliptocytosis (HE). HPP involves a functional defect in spectrin, which is the major cytoskeletal protein of the RBC cell membrane. It manifests as a severe hemolytic anemia with thermal instability of the red blood cells. (See Presentation and Workup.)
Patients with HPP who develop severe hemolytic anemia require, transfusion of packed red blood cells. Folate supplementation is also necessary in chronic hemolytic disease. In the acute care setting, supportive measures (eg, intravenous fluids, oxygen, monitoring of blood counts) are provided according to the needs of the individual patient. (See Treatment.)
Hereditary pyropoikilocytosis (HPP) is a disease emanating from a defect in spectrin, which is the major peripheral protein of the red blood cell (RBC) membrane. This blood disorder is characterized by a red cell morphology similar to that seen in patients suffering from extensive burns—hence the term pyropoikilocytes.
HPP is considered a subtype of the more common disorder hereditary elliptocytosis (HE). HPP is characterized by an abnormality in both horizontal (spectrin self association defect) and vertical (spectrin deficiency) RBC membrane protein interaction. This results in severe hemolytic anemia as the RBC's lipid membrane destabilizes and loses its abilty to withstand intravascular shear stress.
Hereditary pyropoikilocytosis (HPP) is a rare cause of severe hemolytic anemia. Up to a third of family members of patients with HPP have hereditary elliptocytosis (HE).
HPP is mostly observed in people of African descent, but it has been documented in people of European and Arab descent. It has no gender predominance. The disorder is usually discovered in infancy or early childhood when the affected person presents with severe hemolytic anemia. These patients can present with classic HE later in life.
Complications of HE and HPP are similar to those of the more common disorder hereditary spherocytosis (HS). These are generally related to chronic hemolysis and include the following:
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