Case Report: Short rib-thoracic dysplasia type 3 presenting with predominant respiratory manifestations.

Short rib-thoracic dysplasia type 3 (SRTD3) is a rare skeletal ciliopathy caused by pathogenic variants in DYNC2H1, with a broad spectrum of clinical severity ranging from lethal neonatal disease to mild phenotypes presenting later in childhood. We report a 20-month-old girl who presented with recurrent infection-associated wheezing and a rhinovirus-associated acute lower respiratory tract infection complicated by hypoxemia and respiratory distress. Chest computed tomography revealed bilateral patchy ground-glass opacities with focal consolidation and a mildly narrowed thoracic cage with shortened ribs, while skeletal radiographs demonstrated subtle shortening of the long bones and mild acetabular dysplasia. Prenatal ultrasonography did not reveal characteristic fetal skeletal abnormalities, and no prenatal genetic testing was performed. Postnatally, whole-exome sequencing was performed because of developmental delay and recurrent respiratory infections, identifying compound heterozygous DYNC2H1 variants comprising a paternally inherited synonymous splice-altering variant and a large exon 1-88 deletion identified by WES-based copy-number analysis and reported as maternally inherited. Together with the characteristic radiographic findings, these genetic findings supported the diagnosis of SRTD3. This case illustrates that respiratory manifestations may attract clinical attention before the skeletal phenotype is recognized in mild SRTD3, particularly when skeletal abnormalities are subtle. It adds to the emerging spectrum of mild postnatal DYNC2H1-related SRTD3 and highlights the importance of integrating clinical, radiologic, and genetic findings in children with recurrent respiratory symptoms and subtle skeletal abnormalities.