BACKGROUND: Primary ciliary dyskinesia (PCD) is a group of rare genetically heterogeneous disorders caused by defective cilia and flagella motility. The clinical phenotype of PCD patients commonly includes chronic oto-sino-pulmonary disease, infertility, and, in about half of cases, laterality defects due to randomization of left-right body asymmetry. To date, pathogenic variants in more than 50 genes responsible for motile cilia structure and assembly have been reported in such patients. While multiple population-specific mutations have been described in PCD cohorts from different countries, the data on genetic spectrum of PCD in Russian population are still extremely limited.
RESULTS: The present study provides a comprehensive clinical and genetic characterization of 21 Russian families with PCD living in various country regions. Anomalies of ciliary beating in patients` respiratory epithelial cells were confirmed by high-speed video microscopy. In the most cases, custom-designed panel sequencing allowed to uncover causative variants in well-known or rarely mentioned PCD-related genes, including DNAH5, DNAH11, CFAP300, LRRC6, ZMYND10, CCDC103, HYDIN, ODAD4, DNAL1, and OFD1. The variations comprised common mutations, as well as novel genetic variants, some of which probably specific for Russian patients. Additional targeted analysis of mRNA transcripts from ciliated cells enabled us to specify functional effects of newly identified genetic variants in DNAH5 (c.2052+3G>T, c.3599-2A>G), HYDIN (c.10949-2A>G, c.1797C>G), and ZMYND10 (c.510+1G>C) on splicing process. In particular, the splice site variant c.2052+3G>T, detected in four unrelated families, resulted in skipping of exon 14 in DNAH5 transcripts and, according to haplotype analysis of affected probands, was proposed as an ancestral founder mutation in Udmurt population.
CONCLUSIONS: The reported data provide a vital insight into genetic background of primary ciliary dyskinesia in the Russian population. The findings clearly illustrate the utility of gene panel sequencing coupled with transcriptional analysis in identification and clinical interpretation of novel genetic variants.

BACKGROUND: Primary ciliary dyskinesia (PCD) is a rare genetical disease with malfunction of the motile cilia leading to impaired muco-ciliary clearance in the respiratory tract. There is no cure for PCD, only supportive therapy aimed at minimizing the progression of the disease and improving the patient\'s quality of life (QoL). Physical activity (PA) is one of these recommended supportive therapies for people with PCD (pwPCD). However, there is no scientific evidence to support this recommendation. In addition, regular medical advice to increase PA remains largely ineffective in pwPCD.
METHODS: To test the main hypothesis, that an individualized and supported PA program leads to a better QoL 6 months after randomization (QoL-PCD questionnaire) compared to usual recommendation in pwPCD, 158 pwPCD aged 7 to 55 years are to be included in this multi-center randomized controlled trial (RCT). After the screening visit, a 1:1 randomization stratified by age group and FEV1 will be performed. A QoL-PCD questionnaire, motor test, and lung function will be carried out at regular intervals in both groups. PA is recorded in both groups using activity trackers during the study period. The main aim of the trial is to estimate the difference in the change of QoL between the groups after 6 months. Therefore, our full analysis set consists of all randomized patients and analysis is performed using the intention-to-treat principle. Statistical software R ( http://www.r-project.org ) is used. Ethical approvement without any reservations: RUB Bochum Ethics Committee (No. 23-7938; December 4, 2023). Recruitment start: March 2024.
CONCLUSIONS: Limitations result from the rarity of PCD with its broad disease spectrum and the large age range. These are reduced by stratified randomization and the measurement of the individual change in QoL as primary endpoint. In our view, only a PA program tailored to individual needs with close contact to trainers offers the chance to meet personal needs of pwPCD and to establish PA as a pillar of therapy in the long term. The study protocol explains all procedures and methods of recruitment, implementation of the study visits and intervention, measures for patient and data safety, and for minimizing risks and bias.
BACKGROUND: German Clinical Trials Register (DRKS) 00033030. Registered on December 7, 2023. Update 10 July 2024. STUDY PROTOCOL VERSION 10: Version 1.2; 12 June 2024.

This review article explores the respiratory aspects of primary ciliary dyskinesia (PCD), a rare, heterogenous, genetic disorder characterized by impaired motile ciliary function. It discusses the clinical diagnosis and management strategies for PCD-related respiratory disease, including chronic sinusitis, otitis media with effusion, recurrent pneumonia, and bronchiectasis. The review emphasizes the need for a multidisciplinary approach to optimize care and clinical trials to improve outcomes in individuals with PCD, highlighting the importance of accurate diagnosis.

Primary ciliary dyskinesia (PCD) is a genetic condition that results in dysmotile cilia. The repercussions of cilia dysmotility and gene variants on the multiciliated cell remain poorly understood. We used single-cell RNA-Seq, proteomics, and advanced microscopy to compare primary culture epithelial cells from patients with PCD, their heterozygous mothers, and healthy individuals, and we induced pluripotent stem cells (iPScs) generated from a patient with PCD. Transcriptomic analysis revealed unique signatures in PCD airway cells compared with their mothers\' cells and the cells of healthy individuals. Gene expression in heterozygous mothers\' cells diverged from both control and PCD cells, marked by increased inflammatory and cellular stress signatures. Primary and iPS-derived PCD multiciliated cells had increased expression of glutathione-S-transferases GSTA2 and GSTA1, as well as NRF2 target genes, accompanied by elevated levels of reactive oxygen species (ROS). Immunogold labeling in human cilia and proteomic analysis of the ciliated organism Chlamydomonas reinhardtii demonstrated that GSTA2 localizes to motile cilia. Loss of human GSTA2 and C. reinhardtii GSTA resulted in slowed cilia motility, pointing to local cilia regulatory roles. Our findings identify cellular responses unique to PCD variants and independent of environmental stress and uncover a dedicated ciliary GSTA2 pathway essential for normal motility that may be a therapeutic target.

Data are limited on the genetic profile of primary ciliary dyskinesia (PCD) from developing countries. Here, we report one of the first study on genetic profile of patients with suspected PCD from India. In this prospective cross-sectional study, we enrolled 162 children with suspected PCD. We recorded clinical features, relevant laboratory tests for PCD and performed whole exome sequencing (WES). We are reporting 67 patients here who had positive variant/s on WES. We had 117 variants in 40 genes among 67 patients. Among the 108 unique variants, 33 were categorized as pathogenic or likely pathogenic (P/LP). We had nine novel variants in out cohort. The 29 definite PCD cases, diagnosed by composite reference standards, had variants in 16 genes namely LRRC6/DNAAF11 (5), DNAH5 (3), CCDC39 (3), HYDIN (3), DNAH11 (2), CCDC40 (2), CCDC65 (2) and one each DNAAF3, DNAAF2, CFAP300, RPGR, CCDC103, CCDC114, SPAG1, DNAI1, and DNAH14. To conclude, we identified 108 unique variants in 40 genes among 67 patients. The common genes involved in definite cases of PCD in Indian patients were LRRC6, DNAH5, CCDC39, and HYDIN. Our findings suggest a need to develop a separate genetic panel for PCD in the Indian population.

TTC12 is a cytoplasmic and centromere-localized protein that plays a role in the proper assembly of dynein arm complexes in motile cilia in both respiratory cells and sperm flagella. This finding underscores its significance in cellular motility and function. However, the wide role of TTC12 in human spermatogenesis-associated primary ciliary dyskinesia (PCD) still needs to be elucidated. Whole-exome sequencing (WES) and Sanger sequencing were performed to identify potentially pathogenic variants causing PCD and multiple morphological abnormalities of sperm flagella (MMAF) in an infertile Pakistani man. Diagnostic imaging techniques were used for PCD screening in the patient. Real-time polymerase chain reaction (RT‒PCR) was performed to detect the effect of mutations on the mRNA abundance of the affected genes. Papanicolaou staining and scanning electron microscopy (SEM) were carried out to examine sperm morphology. Transmission electron microscopy (TEM) was performed to examine the ultrastructure of the sperm flagella, and the results were confirmed by immunofluorescence staining. Using WES and Sanger sequencing, a novel homozygous missense variant (c.C1069T; p.Arg357Trp) in TTC12 was identified in a patient from a consanguineous family. A computed tomography scan of the paranasal sinuses confirmed the symptoms of the PCD. RT-PCR showed a decrease in TTC12 mRNA in the patient\'s sperm sample. Papanicolaou staining, SEM, and TEM analysis revealed a significant change in shape and a disorganized axonemal structure in the sperm flagella of the patient. Immunostaining assays revealed that TTC12 is distributed throughout the flagella and is predominantly concentrated in the midpiece in normal spermatozoa. In contrast, spermatozoa from patient deficient in TTC12 showed minimal staining intensity for TTC12 or DNAH17 (outer dynein arms components). This could lead to MMAF and result in male infertility. This novel TTC12 variant not only illuminates the underlying genetic causes of male infertility but also paves the way for potential treatments targeting these genetic factors. This study represents a significant advancement in understanding the genetic basis of PCD-related infertility.

BACKGROUND: Kartagener syndrome is rare, with an incidence of 1 in 32,000 live births. It consists of a triad of bronchiectasis, situs inversus, and sinusitis. Normally, the middle lobe is part of the right lung, but due to situs inversus, the middle lobe is part of the left lung, making it prone to bronchiectasis and infections.
METHODS: We present a unique case of a 16-year-old adolescent with a known history of Kartagener syndrome who presented with recurrent chest infections and hemoptysis refractory to conservative management. He was diagnosed with bronchiectasis of the left middle lobe through a computed tomography (CT) scan and subsequently underwent a posterolateral thoracotomy and left middle lobectomy. This is a rare finding with limited literature available on such cases, to the best of our knowledge.
CONCLUSIONS: Conservative treatment is usually the first line of approach. However, in cases of recurrent chest infections and hemoptysis, surgical management is considered to prevent the infection from spreading to the healthy lung and to avoid life-threatening complications when medical therapy fails. Surgical intervention, while more invasive, can provide a definitive solution and improve the patient\'s quality of life.
CONCLUSIONS: Early diagnosis of Kartagener syndrome is crucial for determining the appropriate management course. In patients presenting with recurrent hemoptysis and chest infections, surgical resection is an effective treatment approach to prevent complications and enhance long-term outcomes.

Left-right patterning is among the least well understood of the three axes defining the body plan, and yet it is no less important, with left-right patterning defects causing structural birth defects with high morbidity and mortality, such as complex congenital heart disease, biliary atresia, or intestinal malrotation. The cell signaling pathways governing left-right asymmetry are highly conserved and involve multiple components of the TGF-β superfamily of cell signaling molecules. Central to left-right patterning is the differential activation of Nodal on the left, and BMP signaling on the right. In addition, a plethora of other cell signaling pathways including Shh, FGF, and Notch also contribute to the regulation of left-right patterning. In vertebrate embryos such as the mouse, frog, or zebrafish, the specification of left-right identity requires the left-right organizer (LRO) containing cells with motile and primary cilia that mediate the left-sided propagation of Nodal signaling, followed by left-sided activation of Lefty and then Pitx2, a transcription factor that specifies visceral organ asymmetry. While this overall scheme is well conserved, there are striking species differences, including the finding that motile cilia do not play a role in left-right patterning in some vertebrates. Surprisingly, the direction of heart looping, one of the first signs of organ left-right asymmetry, was recently shown to be specified by intrinsic cell chirality, not Nodal signaling, possibly a reflection of the early origin of Nodal signaling in radially symmetric organisms. How this intrinsic chirality interacts with downstream molecular pathways regulating visceral organ asymmetry will need to be further investigated to elucidate how disturbance in left-right patterning may contribute to complex CHD.

Defects of situs are associated with complex sets of congenital heart defects in which the normal concordance of asymmetric thoracic and abdominal organs is disturbed. The cellular and molecular mechanisms underlying the formation of the embryonic left-right axis have been investigated extensively in the past decade. This has led to the identification of mutations in at least 33 different genes in humans with heterotaxy and situs defects. Those mutations affect a broad range of molecular components, from transcription factors, signaling molecules, and chromatin modifiers to ciliary proteins. A substantial overlap of these genes is observed with genes associated with other congenital heart diseases such as tetralogy of Fallot and double-outlet right ventricle, d-transposition of the great arteries, and atrioventricular septal defects. In this chapter, we present the broad genetic heterogeneity of situs defects including recent human genomics efforts.

Formation of the vertebrate heart with its complex arterial and venous connections is critically dependent on patterning of the left-right axis during early embryonic development. Abnormalities in left-right patterning can lead to a variety of complex life-threatening congenital heart defects. A highly conserved pathway responsible for left-right axis specification has been uncovered. This pathway involves initial asymmetric activation of a nodal signaling cascade at the embryonic node, followed by its propagation to the left lateral plate mesoderm and activation of left-sided expression of the Pitx2 transcription factor specifying visceral organ asymmetry. Intriguingly, recent work suggests that cardiac laterality is encoded by intrinsic cell and tissue chirality independent of Nodal signaling. Thus, Nodal signaling may be superimposed on this intrinsic chirality, providing additional instructive cues to pattern cardiac situs. The impact of intrinsic chirality and the perturbation of left-right patterning on myofiber organization and cardiac function warrants further investigation. We summarize recent insights gained from studies in animal models and also some human clinical studies in a brief overview of the complex processes regulating cardiac asymmetry and their impact on cardiac function and the pathogenesis of congenital heart defects.