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NEETZoologyPrinciples of Inheritance and Variation

What is the main defect in sickle-cell anaemia?

Options

  1. ADefect in the red blood cell membrane
  2. BSubstitution of Glutamic acid by Valine in the beta globin chain
  3. CDeletion of a gene involved in hemoglobin synthesis
  4. DExtra chromosome affecting the red blood cells

Correct answer

B. Substitution of Glutamic acid by Valine in the beta globin chain

Step-by-step solution

This is an autosome linked recessive trait that can be transmitted from parents to the offspring when both the partners are carrier for the gene (or heterozygous). The disease is controlled by a single pair of allele, HbA and HbS . Out of the three possible genotypes only homozygous individuals for HbS (HbSHbS ) show the diseased phenotype. Heterozygous (HbAHbS ) individuals appear apparently unaffected but they are carrier of the disease as there is 50 per cent probability of transmission of the mutant gene to the

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