Principles of Inheritance and Variation

Inheritance of blood groups


  • Blood group inheritance follows codominance.
  • Alleles responsible are IA, IB and I0 [IA and IB – dominant ; I0 – recessive]
  • The possible number of genotypes from 3 alleles are \frac{3(3+1)}{2}=6
  • IA, IA → ‘A’
    IA, IB → ‘AB’ [codominance]
    IB, IB → ‘B’
    I0, I0 → ‘O’
    IA, I0 → ‘A’ ; IB − I0 → ‘B’
  • Three blood group A, B and ‘O’ were discovered by Landsteiner and one blood group AB was discovered by de castello and steini.

Watch this video for the topic from 0:15 to 9:53

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