[Clinical and genetic analysis of a child with Primary ciliary dyskinesia variants and co-existence of CCDC39 gene variants and 22q11.21 deletion].

Objective: To analyze the clinical and genetic features of a child with Primary ciliary dyskinesia (PCD) due to compound heterozygous variants of the CCDC39 gene and a 22q11.21 deletion, and to explore the potential role of the two types of variants in the formation of complex phenotypes.

Methods: A child presented at the Shanxi Children's Hospital in March 2025 due to multiple congenital anomalies was selected as the study subject. Peripheral blood samples were taken from the child and her parents and subjected to whole-exome sequencing (WES). Candidate variants were verified by Sanger sequencing. Effect of splicing variant was predicted using SpliceAI, and pathogenicity was assessed based on the ACMG guidelines. Copy number variation (CNV) analysis was also performed. This study has been approved by the Medical Ethics Committee of the Hospital (Ethics No.: IRB-WZ-2025-019).

Results: The patient has exhibited multiple features including severe pneumonia, bronchiectasis, localized pulmonary emphysema, scoliosis, tetralogy of Fallot, and atrial septal defect. Genetic testing revealed that she has harbored compound heterozygous variants of the CCDC39 gene, namely c.1167+1G>A and c.1009A>T, which were inherited from her father and mother, respectively, with the latter being a novel likely pathogenic variant. In addition, a heterozygous deletion of approximately 708 kb at 22q11.21 was detected.

Conclusion: The coexistence of CCDC39 gene variants and a 22q11.21 deletion may underlay the development of complex clinical phenotypes in this child.