Table 99-1 Classification of Hemoglobinopathies

I. Structural hemoglobinopathies—hemoglobins with altered amino acid sequences that result in deranged function or altered physical or chemical properties A. Abnormal hemoglobin polymerization—HbS, hemoglobin sickling B. Altered O2 affinity 1. High affinity—polycythemia 2. Low affinity—cyanosis, pseudoanemia C. Hemoglobins that oxidize readily 1. Unstable hemoglobins—hemolytic anemia, jaundice 2. M hemoglobins—methemoglobinemia, cyanosis II. Thalassemias—defective biosynthesis of globin chains A. alpha Thalassemias B. beta Thalassemias C. gamma-beta, gamma-delta-beta, alpha-beta Thalassemias III. Thalassemic hemoglobin variants—structurally abnormal Hb associated with co-inherited thalassemic phenotype A. HbE B. Hb Constant Spring C. Hb Lepore IV. Hereditary persistence of fetal hemoglobin   —persistence of high levels of HbF into adult life V. Acquired hemoglobinopathies A. Methemoglobin due to toxic exposures B. Sulfhemoglobin due to toxic exposures C. Carboxyhemoglobin D. HbH in erythroleukemia E. Elevated HbF in states of erythroid stress and bone marrow dysplasia