What type of defect causes sickle cell anaemia

  • Sickle cell anaemia

    • Autosomal recessive disease
    • Transmission − From parent to offspring when both parents are carriers of disease
    • Pair of alleles HbA and HbS controls the expression of this disease.
      HbA and HbA − Normal
      HbA and HbS − Carrier of disease
      HbS and HbS − Diseased
    • Cause of the disease − Change in gene causes the replacement of GAG by GUG leading to the substitution of Glu by Val at sixth position of beta globin chain of haemoglobin.
    • The mutant haemoglobin so formed polymerises at low oxygen tension, resulting in change in shape of RBC to sickle-like.

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