Hemoglobin electrophoresis in SC A (sickle cell anemi
Correct Answer: HbA
Description: Ans. a (Hb A) (Ref. William haemat 7th/pg. 670,678; Wintrobe's haemat 11th /pg. 1288).William's 680 .... " Because there are no p-polypeptide chain genes, patients with SCA have no NORMAL Hb A".Electrophoresis in Sickle cell anaemia# Hb S -50%# Hb F -Variable# Hb A2 -Normal# Hb A - AbsentSummary: Sickle cell anaemia# HbS point mutation causes a single amino acid replace in a chain (substitution of glutamic acid with valine) at position 6.# Pathogenesis: low O2, dehydration, or acidosis precipitates sickling (deoxygenated HbS polymerizes), which results in anemia and vaso-occlusive disease.# Newborns are initially asymptomatic because of *HbF and>>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++.
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