- More than 80% of hemoglobin is abnormal (HbS) causing serious clinical complications: anemia, sickle shaped erythrocytes; recurrent and painful crises; non-healing leg ulcers. Splenic infarcts.
- Thalassemia---one or more of the genes responsible for the synthesis of Alpha or beta globin chains is abnormal.
Alpha-thalassemia –deletion of one or more alpha globin genes; range from no clinical abnormalities to fetal death (4 deletions); less severe than Beta thalassemia
Beta-thalassemia---mutation in Beta-globin gene o Thalassemia minor—heterozygous—mild anemia o Thalassemia major (also called Cooley’s anemia, Mediterranean anemia)—homozygous---severe anemia requiring frequent blood transfusions to sustain life.