Question

Sol.(d) [Key Concept: Down's Syndrome — Trisomy 21] A person with 47 chromosomes due to THREE copies of chromosome 21 (trisomy 21) has DOWN'S SYNDROME. The extra chromosome 21 results from non-disjunction during meiosis. Down's syndrome is characterised by intellectual disability, characteristic facial features (flat face, almond-shaped eyes), short stature, and often heart defects. Note: Down's syndrome affects both sexes; Turner's syndrome is 45,X (females); superfemale = XXX (47,XXX).