Genomic Complexity of ccdc40 in Xenopus : Implications for CRISPR Targeting and Disease Modeling

Mutations in CCDC40 cause primary ciliary dyskinesia in humans. To evaluate the pathogenicity of variants in CCDC40 , we examined the genomic structure of this gene in Xenopus tropicalis , a diploid frog suitable as a model for genetic studies. We identified inconsistencies in the current ccdc40 gene model and discovered two distinct ccdc40 genes near the previously annotated locus. Surprisingly, Xenopus laevis , an allotetraploid species that typically has two homoeologs, contains only one homoeolog ( ccdc40.S ), making it a more suitable genetic model for studying ccdc40 function and potentially expediting the functional characterization of CCDC40 variants linked to primary ciliary dyskinesia.