Trisomy 21 (Down Syndrome)

Trisomy 21, or Down syndrome, results from an extra copy of chromosome 21 due to nondisjunction during meiosis. This chromosomal abnormality leads to overexpression of genes on chromosome 21, affecting multiple organ systems. The extra genetic material disrupts normal development, causing characteristic physical features, intellectual disability, and increased risk of congenital heart defects. Down syndrome is the most common chromosomal cause of intellectual disability. The nurse assists with monitoring growth and development, supporting feeding, and reporting changes in respiratory or cardiac status.