Primary ciliary dyskinesia phenotypes and correlation with genotype.

Purpose of review: Primary ciliary dyskinesia is a rare, inherited disease, and over 60 genes have been linked to motile ciliopathies. During the past quarter century, our understanding of the complex genetics and biological function of motile cilia has greatly advanced.

Recent findings: Our growing knowledge of genetics and pathophysiology of primary ciliary dyskinesia has yielded insights into novel clinical features and genotype-phenotype relationships in motile ciliopathies. Children with biallelic CCDC39 or CCDC40 mutations have greater lung disease, related to both cilia motility-dependent and motility-independent effects. Pathogenic variants in genes involved in cilia generation, like CCNO , are also associated with more severe lung disease. Conversely, people who have defects in other genes, like DHAH11 and RSPH1 , have less severe lung disease, possibly related to residual ciliary motility. Finally, a growing number of primary ciliopathies are associated with abnormal motile cilia ultrastructure and function, and specific pathogenic variants can lead to distinct clinical presentations, best illustrated by structure-function studies in TUBB4B .

Summary: These findings have yielded new insights into the clinical heterogeneity of motile ciliopathies, thus broadening their clinical spectrum. Additional research to elucidate the underlying pathophysiology in these overlapping conditions is warranted.