MNS1 (meiosis-specific nuclear structural protein-1) is a microtubule inner protein component of motile cilia and sperm flagella axonemes essential for proper ciliary and flagellar function 1. The protein plays a critical role in outer dynein arm-docking complex (ODA-DC) assembly, which mediates outer dynein arm binding to axonemal doublet microtubules 2. MNS1 localizes to respiratory epithelial cilia and sperm flagella, where it dimerizes and interacts with CCDC114, a key ODA-DC component 2. Biallelic MNS1 mutations cause MNS1-related motile ciliopathy, an autosomal recessive disorder characterized by laterality defects including situs inversus totalis and heterotaxia, combined with male infertility 34. Affected individuals exhibit reduced or absent outer dynein arms in respiratory cilia 2. Recent clinical observations extend the phenotype to include respiratory disease, with affected individuals presenting neonatal respiratory distress syndrome, recurrent respiratory tract infections, and chr15 rhinitis 4. Additionally, compound heterozygous MNS1 variants have been associated with complete situs inversus accompanied by severe myopia and dental agenesis 5. The disorder represents one of at least 33 genes implicated in human heterotaxy and situs defects 6, establishing MNS1 as a critical component of ciliary-mediated left-right axis development and respiratory mucociliary clearance.