Trisomy 9 mosaicism: a genetic disorder with complications—a case report

This case is unique for several reasons: micrognathia requiring distraction, absent external ears, severe pulmonary hypertension requiring patent ductus arteriosus closure, and long-term oxygen therapy. To our knowledge, this is the first reported trisomy 9 mosaicism case with such a severe pulmonary hypertensive crisis necessitating aggressive intervention. Although historically associated with poor outcomes, improved neonatal care contributes to increasing survival in infants with trisomy 9 mosaicism.