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Q.Give one example of an autosomal genetic disease. What is its reason?

West Bengal WbchseWest Bengal HS (WBCHSE) Board 2019Subjective· 2mImportance★★★★★
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An autosomal genetic disease is one whose defective gene lies on an autosome (not a sex chromosome). Sickle-cell anaemia is a classic example, caused by a single point mutation in the β-globin gene that substitutes valine for glutamic acid at the 6th position.

Autosomal genetic disease — a hereditary disorder controlled by a gene located on one of the 22 pairs of autosomes, so it affects males and females equally.

Example: Sickle-cell anaemia (autosomal recessive).

Reason (the molecular cause):

  1. The disease results from a point mutation (substitution) in the gene coding for the beta-globin chain of haemoglobin.
  2. The mRNA codon at the 6th position changes from GAG to GUG (the DNA changes GAG → GTG).
  3. As a result, the amino acid glutamic acid (Glu) is replaced by valine (Val) at the sixth position of the β-chain. …

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