Which genetic disorder is caused by an extra copy of chromosome 21, resulting in developmental delays and distinct physical features?

💡 Solution & Explanation

Down syndrome is a congenital chromosomal disorder caused by the presence of an extra full or partial copy of chromosome 21, leading to characteristic physical growth delays and mild to moderate intellectual disability. Alternative conditions such as Turner syndrome and Klinefelter syndrome involve sex chromosome anomalies rather than autosome trisomy.