Trisomy 21 (Down Syndrome)

Trisomy 21 results from an extra copy of chromosome 21. Meiotic nondisjunction is the most common mechanism; translocation and mosaic forms occur less often. The additional genetic material increases expression of chromosome 21 genes during development, so the effects extend well beyond appearance or developmental milestones. The clinical pattern may include characteristic facial features, hypotonia, developmental differences, and multisystem anomalies. Congenital heart disease, hearing and vision problems, thyroid dysfunction, obstructive sleep apnea, celiac disease, and altered growth patterns are especially relevant to nursing surveillance. The range is broad: a diagnosis suggests risks to anticipate, not a fixed level of ability or a predetermined course. That distinction shapes care. The nurse should use the child’s actual assessment findings and functional abilities rather than attributing every symptom to Down syndrome. A child with trisomy 21 can still develop the same acute illness as any other child, and a new symptom deserves a new assessment.