Novel Co‐Occurrence of Trisomy 21 and Heterozygous <scp>CFTR</scp> Mutation

The coexistence of trisomy 21 and cystic fibrosis (CF) is extremely rare, with fewer than 10 reported cases, all involving homozygous CFTR mutations. However, the impact of a heterozygous CFTR mutation in a patient with trisomy 21 remains unexplored. We present a male infant with trisomy 21 who experienced recurrent respiratory distress and was later found to carry a heterozygous pathogenic CFTR mutation (p.Phe508del). His respiratory complications were severe, requiring tracheostomy and long-term respiratory support. This case highlights the potential interplay between trisomy 21-associated anatomical features and CFTR-related airway abnormalities, possibly exacerbating respiratory morbidity. Given the high burden of respiratory complications in both conditions, clinicians should consider CFTR-related disorders in patients with trisomy 21 presenting with severe respiratory issues. Further research is warranted to determine the clinical significance of CFTR heterozygosity in trisomy 21 and its implications for disease severity and management.