Recessive DNAH9 loss-of-function mutations cause laterality defects and subtle respiratory ciliary-beating defects

Dysfunction of motile monocilia, altering the leftward flow at the embryonic node essential for determination of left-right body asymmetry, is a major cause of laterality defects. Laterality defects are also often associated with reduced mucociliary clearance caused by defective multiple motile cilia of the airway and are responsible for destructive airway disease. Outer dynein arms (ODAs) are essential for ciliary beat generation, and human respiratory cilia contain different ODA heavy chains (HCs): the panaxonemally distributed γ-HC DNAH5, proximally located β-HC DNAH11 (defining ODA type 1), and the distally localized β-HC DNAH9 (defining ODA type 2). Here we report loss-of-function mutations in DNAH9 in five independent families causing situs abnormalities associated with subtle respiratory ciliary dysfunction. Consistent with the observed subtle respiratory phenotype, high-speed video microscopy demonstrates distally impaired ciliary bending in DNAH9 mutant respiratory cilia. DNAH9-deficient cilia also lack other ODA components such as DNAH5, DNAI1, and DNAI2 from the distal axonemal compartment, demonstrating an essential role of DNAH9 for distal axonemal assembly of ODAs type 2. Yeast two-hybrid and co-immunoprecipitation analyses indicate interaction of DNAH9 with the ODA components DNAH5 and DNAI2 as well as the ODA-docking complex component CCDC114. We further show that during ciliogenesis of respiratory cilia, first proximally located DNAH11 and then distally located DNAH9 is assembled in the axoneme. We propose that the β-HC paralogs DNAH9 and DNAH11 achieved specific functional roles for the distinct axonemal compartments during evolution with human DNAH9 function matching that of ancient β-HCs such as that of the unicellular Chlamydomonas reinhardtii

Primary Ciliary Dyskinesia Associated Disease-Causing Variants in <i>CCDC39</i> and <i>CCDC40</i> Cause Axonemal Absence of Inner Dynein Arm Heavy Chains DNAH1, DNAH6, and DNAH7

Disease-causing bi-allelic DNA variants in CCDC39 and CCDC40 are frequent causes of the hereditary disorder of primary ciliary dyskinesia (PCD). The encoded proteins form a molecular ruler complex, crucial for maintaining the 96 nm repeat units along the ciliary axonemes. Defects of those proteins cause a stiff, rapid, and flickery ciliary beating pattern, recurrent respiratory infections, axonemal disorganization, and abnormal assembly of GAS8, CCDC39, and DNALI1. We performed molecular characterization of the defects in the 96 nm axonemal ruler due to disease-causing variants in CCDC39 and CCDC40 and analyzed the effect on additional axonemal components. We identified a cohort of 51 individuals with disease-causing variants in CCDC39 and CCDC40 via next-generation sequencing techniques and demonstrated that the IDA heavy chains DNAH1, DNAH6, and DNAH7 are conspicuously absent within the respiratory ciliary axonemes by immunofluorescence analyses. Hence, we show for the first time that the centrin2 (CETN2) containing IDAs are also affected. These findings underscore the crucial role of CCDC39 and CCDC40 in the assembly and function of IDAs in human respiratory cilia. Thus, our data improve the diagnostics of axonemal ruler defects by further characterizing the associated molecular IDA defects

Generation of induced pluripotent stem cell lines from a Crisponi/Cold induced sweating syndrome type 1 individual

Cytokine receptor like factor 1 (CRLF1) is the gene implicated, when mutated, in Crisponi syndrome/cold-induced sweating syndrome type 1 (CS/CISS1). Here, we report the establishment of induced pluripotent stem cell lines (iPSCs) from fibroblasts of a Turkish CS/CISS1 individual with a homozygous variant in CRLF1 (c.708_709delinsT; p.[Pro238Argfs*6]). This variant is the most frequent variant associated to CS/CISS1 in the Turkish population. These patient derived iPSC lines show all pluripotency markers, a normal karyotype and the ability to differentiate into the three germ layers

Mutations in CCDC11, which encodes a coiled-coil containing ciliary protein, causes situs inversus due to dysmotility of monocilia in the left-right organizer

10.1002/humu.22738Human Mutation 363307-31