Definition:

Hereditary pyropoikilocytosis (HPP) is a recessively inherited form of hemolytic anemia characterized by peripheral blood morphology presenting with striking anisopoikilocytosis with red cell fragmentation and microspherocytes. Erythrocytes from most HPP patients exhibit qualitative and quantitative abnormalities of the erythrocyte membrane protein spectrin, the principal structural component of the erythrocyte membrane skeleton. Qualitative spectrin defects are typically associated with missense mutations that lead to abnormal spectrin self-association, a process critical for membrane structure and function.