Point mutation in 6th codon of β-globin gene so there is replacement of glutamate with valine
Production of Hb with abnormal physiochemical properties that promotes polymerization of deoxygenated Hb
Heterozygous Trait: sickle cell trait –protects against falciparum
Homozygous Trait: sickle cell disease
On Deoxygenation, HbS forms long polymers
RBC membrane damage
Microvascular obstruction leading to ischemia & tissue damage.
Hemolysis in Reticuloendothelial system
Usually presents after 6 months of age
Anemia: pallor, generalized weakness
Hand foot syndrome (dactylitis of hands & foot)
Priapism (in 45% of affected male) & erectile dysfunction
Auto splenectomy due to splenic infarcts: predisposes to infection by encapsulated organisms
Renal papillary necrosis
Infection is M/C cause of death in children < 3 yrs of age
Crises in sickle cell disease
vaso occlusive crisis:painful
aplastic crisis: parvovirus B19
acute chest syndrome
PS: evidence of hemolysis, sickle cells, Howel Jolly bodies
(SICKLING TEST: mixing a blood sample with metabisulfite or dithionite induces sickling of RBCs, if HbS is present)
Spleen biopsy: Gamma Gandy bodies
Hb Electrophoresis to detect HbS peak
Confirmatory test: genetic defect checked
Avoid infections & do immunisation
Acute painful crisis: analgesia
Hydroxyurea for patients with severe symptoms (increases HbF levels)
Bone marrow transplantation
HbD: in punjabi/sindhis
HbE: in Bengal/ NE states
Previous Year's Question
A boy after playing football complaining and abdominal pain. He also had a history of hand swelling in past. On USG, he has shrunken spleen. What is the likely diagnosis of this patient? (NEET Jan 2020)
Sickle cell anemia
Abnormal chromosomal fragility (demonstrated using Diepoxybutane or Mitomycin C)
Most common Hyperpigmentation, café au lait spots
Absent radius, hypoplastic thumb.
Facial dysmorphism: Microcephaly, small eyes, epicanthic folds, abnormal ears.
Renal/ CNS/GIT malformations
Complications: Increased risk of tumors like squamous cell Carcinoma of Head/ Neck/Esophagus.
HSCT (definitive treatment)
Inherited/acquired condition with pancytopenia with hypo/acellular bone marrow
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