>HbS.# In SC A, mean MCHC Increase, Hb is between 5-10 g%# Heterozygotes (sickle cell trait) have resistance to malaria.# "Crew cut" on skull x-ray due to marrow expansion from*erythropoiesis (also in thalassemias).# Sickling is seen only when sickle cells are present by > 50%# Complications in sickle cell disease (SS): Aplastic crisis (due to parvovirus B19); Autosplenectomy (Howell-Jolly bodies) **risk of infection with encapsulated organisms; Splenic sequestration crisis; Salmonella osteomyelitis; Painful crisis (vaso-occlusive): dactylitis; acute chest syndrome (most common cause of death in adults), avascular necrosis, stroke; Renal papillary necrosis (due to low O2 in papilla; also seen in heterozygotes) and microhematuria (medullary infarcts).# Diagnosis: hemoglobin electrophoresis.# Treatment: (a). To increase HbF with drugs like: 5- azitidine and Hydroxyurea (*HbF). (b). To increase water content of RBC's or to prevent dehydration of cells: Gordos channel inhibitors, Cotrimoxazole and Mg++.">