Autosomal trisomies are associated with major congenital malformations that may 
result in prolonged hospitalization of the newborn. Knowledge about these 
chromosomal abnormalities is important for nurses in neonatal practice. This 
article identifies the causes and manifestations of most of these trisomies: 
trisomy 13 (Patau syndrome), trisomy 18 (Edwards syndrome), and trisomy 21 (Down 
syndrome). More detailed description of the manifestations, associated 
abnormalities, and outcomes of the most common of these, trisomy 21, is 
provided.