Sickle cell anaemia is caused by:
AA point mutation in the β-globin gene
BAn extra chromosome 21 (trisomy 21)
CAn extra X chromosome in males
DA deletion of the Y chromosome in males
Answer & Solution
Correct answer: A. A point mutation in the β-globin gene
Sickle cell anaemia = point mutation in the β-globin gene (GAG to GTG, glutamic acid to valine). HbS replaces HbA, causes RBCs to sickle in low oxygen. Autosomal recessive.
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