Sickle cell (HBB)

• Sickle cell anemia is caused by a substitution mutation on chromosome 11
• GAG is substituted to GTG (Base substitution)
• The allele associated with sickle cell iis recessive
• This substitution causes the hydrophilic R group of red blood cell to become hydrophobic
• results in

  • sickle / crescent shape
  • carry less oxygen
  • get stuck in capillaries
  • break down faster
  • can form long fibres

  -

  However,

  • Heterozygous individuals are seen to be resistant to malaria
• phenotypical features:

  • swelling of hands and feet
  • RBCs pulled out of shape
  • Jaundice
  • kidney failure
  • stroke
  • Increased likelihood of blood clots