Which genetic disorder is caused by the presence of an extra chromosome 21, resulting in Down syndrome?

💡 Solution & Explanation

Down syndrome is a chromosomal anomaly resulting from the presence of three copies of chromosome 21 instead of the usual pair, a condition specifically designated as trisomy 21. Alternative conditions such as monosomy involve the complete absence of one chromosome from a pair, which is typically lethal in humans. Nondisjunction during meiotic cell division is the primary cellular mechanism leading to this chromosomal disorder.