Which of the following genetic disorders is caused by a point mutation? a) Down's Syndrome b) Turner's Syndrome c) Sickle Cell Anaemia d) Klinetelter's syndrome

The correct answer is (c) Sickle Cell Anaemia. This disorder arises due to a point mutation in the HBB gene on chromosome 11, where a single nucleotide substitution (A→T) replaces glutamic acid with valine in the β-globin chain of hemoglobin. This alters the protein structure, causing sickle-shaped red blood cells. In contrast, Down’s, Turner’s, and Klinefelter’s syndromes are chromosomal disorders resulting from abnormal chromosome number (aneuploidy), not point mutations.