Primary Ciliary Dyskinesia Diagnostics Research Articles

A new software for automated analysis of respiratory tract ciliary epithelium movement for the diagnosis of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a rare hereditary disease. In this ciliopathy, the disturbed structure and motility of the ciliary epithelium negatively affects the ciliary function and leads to prominent decrease or absence of mucociliary clearance. The European guidelines recommend analyzing the cilia beat frequency (СBF) in a native preparation or in ALI culture using light microscopy as one of the methods to confirm the diagnosis of PCD.The aim of this project was to create software for automated analysis of the movement/beating of the ciliary epithelium of the respiratory tract for the diagnosis of primary ciliary dyskinesia using digital high-speed video microscopy in vivo and in vitro.Methods. Five healthy donors and 10 patients with suspected PCD underwent nasal epithelial brush biopsy. The preparations were examined with a transmission electron microscope in vivo. Epithelial cells were also isolated from the nasal biopsy specimen, and ciliogenesis of these cells was performed by ALI-culturing, followed by digital high-speed video microscopy and assessment of the number of active cells and cilia beating frequency. The resulting video images were used to create the software.Results. Software for determination of ciliary epithelium beat frequency in primary ciliary dyskinesia (PCD HighSpeed Video Microscopy Analysis – PCD HSVMA) was created to optimize the diagnosis of PCD by light microscopy (software registration number 2023687245). The software is designed to count the number of active cells of ciliary epithelium and CBF (Hz) by digital high-speed video microscopy in vivo and in vitro in ALI-culture. PCD HSVMA software features storage of patient data, display of heat map, formation of a large server database of patients and video files, building of color and static histograms, processing of several areas in one video. Our software has a number of advantages over CiliarMove and Cilialyzer and has high correlation of CFB (Hz) estimation with these products.Conclusion. Our software can be used for improvement of PCD diagnostics in laboratories of healthcare institutions, in scientific institutions and can be included in specialist educational programs for laboratory doctors, pediatricians, general practitioners, pulmonologists, diagnosticians (endoscopists).

A clinical case of primary ciliary dyskinesia in a child under one year old with a pathogenic genetic variant of the DNAH5 gene described for the first time

Relevance: primary ciliary dyskinesia (PCD) is a rare hereditary autosomal recessive disease from the group of ciliopathies, which is based on a defect in the ultrastructure of the cilia of the epithelium of the respiratory tract and similar structures, leading to a violation of their motor function. It is characterized by the defeat of all parts of the respiratory tract with the formation of a chronic inflammatory process and bronchiectasis. About half of patients with PCD have a complete or incomplete reverse arrangement of internal organs with various variants of heterotaxy (situs inversus). Primary ciliary dyskinesia should be differentiated from cystic fibrosis, primary immunodeficiency conditions, congenital anomalies of the structure of the bronchial tree, bronchiectasis of other origin, bronchial asthma, congenital anomalies of the cardiovascular system. Objective: describe the clinical case of a PCD patient with the first-described pathogenic variant of the nucleotide sequence (chr5:13700862CCATAGA>C) of the DNAH5 gene to familiarize doctors with the clinical features of the disease and modern diagnostic capabilities. Materials and methods: the data from the patient’s medical history, transmission electron microscopy to detect anomalies in the structure of cilia in the biopsy of the nasal mucosa and the results of molecular genetic diagnostics were used. Results. The patient was admitted for 8 months for examination and treatment in June 2022. A child from the 1st pregnancy, the first birth at 43 weeks. From anamnesis: suffered intrauterine pneumonia, otitis media without hearing loss, obstructive bronchitis, episodes of apnea. Neonatal screening for cystic fibrosis is negative. According to the PICADOR scale, 12 points were obtained. On high-speed video microscopy of cilia, there is a violation of the movements of the cilia. On computed tomography of the chest organs, the reverse location of the internal organs was noted, there were no pathological changes in the lungs. The total absence of external and internal dynein handles on transmission electron microscopy was revealed. Exome sequencing revealed the previously described variant of the nucleotide sequence in exon 68 of the DNAH5 gene (chr5:13735348G> A) in a heterozygous state. Also, a previously undescribed variant of the nucleotide sequence (chr5:13700862CCATAGA> C) in a heterozygous state was detected in exon 78 of the DNAH5 gene. Conclusion: modern possibilities of PCD diagnostics are demonstrated by the example of clinical observation. It is noted that patients with suspected PCD need a comprehensive examination. A pathogenic variant of the nucleotide sequence (chr5:13700862CCATAGA>C) of the DNAH5 gene in a heterozygous state has been described for the first time, leading to the deletion of two amino acids without shifting the reading frame (c.13604_13609del p. (Val4535_Tyr4536del); NM_001369.3), which will help for the diagnosis of PCD in the future.

Pathogenic gene variants in CCDC39, CCDC40, RSPH1, RSPH9, HYDIN, and SPEF2 cause defects of sperm flagella composition and male infertility.

Primary Ciliary Dyskinesia (PCD) is a rare genetic disorder affecting the function of motile cilia in several organ systems. In PCD, male infertility is caused by defective sperm flagella composition or deficient motile cilia function in the efferent ducts of the male reproductive system. Different PCD-associated genes encoding axonemal components involved in the regulation of ciliary and flagellar beating are also reported to cause infertility due to multiple morphological abnormalities of the sperm flagella (MMAF). Here, we performed genetic testing by next generation sequencing techniques, PCD diagnostics including immunofluorescence-, transmission electron-, and high-speed video microscopy on sperm flagella and andrological work up including semen analyses. We identified ten infertile male individuals with pathogenic variants in CCDC39 (one) and CCDC40 (two) encoding ruler proteins, RSPH1 (two) and RSPH9 (one) encoding radial spoke head proteins, and HYDIN (two) and SPEF2 (two) encoding CP-associated proteins, respectively. We demonstrate for the first time that pathogenic variants in RSPH1 and RSPH9 cause male infertility due to sperm cell dysmotility and abnormal flagellar RSPH1 and RSPH9 composition. We also provide novel evidence for MMAF in HYDIN- and RSPH1-mutant individuals. We show absence or severe reduction of CCDC39 and SPEF2 in sperm flagella of CCDC39- and CCDC40-mutant individuals and HYDIN- and SPEF2-mutant individuals, respectively. Thereby, we reveal interactions between CCDC39 and CCDC40 as well as HYDIN and SPEF2 in sperm flagella. Our findings demonstrate that immunofluorescence microscopy in sperm cells is a valuable tool to identify flagellar defects related to the axonemal ruler, radial spoke head and the central pair apparatus, thus aiding the diagnosis of male infertility. This is of particular importance to classify the pathogenicity of genetic defects, especially in cases of missense variants of unknown significance, or to interpret HYDIN variants that are confounded by the presence of the almost identical pseudogene HYDIN2.

An international survey on nasal nitric oxide measurement practices for the diagnosis of primary ciliary dyskinesia.

Nasal nitric oxide (nNO) measurements are used in the assessment of patients suspected of having primary ciliary dyskinesia (PCD), but recommendations for performing such measurements have not focused on children and do not include all current practices. To guide the development of a European Respiratory Society-supported technical standard for nNO measurement in children, an international online survey was conducted to better understand current measurement practices among providers involved in PCD diagnostics.78 professionals responded, representing 65 centres across 18 countries, mainly in Europe and North America. Nearly all centres measured nNO in children and more than half performed measurements before 5 years of age. The test was often postponed in children with signs of acute airway infection. In Europe, the electrochemical technique was more frequently used than chemiluminescence. A similar proportion of centres performed measurements during exhalation against a resistance (49 out of 65) or during tidal breathing (50 out of 65); 15 centres used only exhalation against a resistance and 15 used only tidal breathing. The cut-off values used to discriminate PCD were consistent across centres using chemiluminescence analysers; these centres reported results as an output (nL·min−1). Cut-off values were highly variable across centres using electrochemical devices, and nNO concentrations were typically reported as ppb.This survey is the first to determine real-world use of nNO measurements globally and revealed remarkable variability in methodology, equipment and interpretation. These findings will help standardise methods and training.

A Comprehensive Approach for the Diagnosis of Primary Ciliary Dyskinesia-Experiences from the First 100 Patients of the PCD-UNIBE Diagnostic Center.

Primary ciliary dyskinesia (PCD) is a rare genetic disease characterized by dyskinetic cilia. Respiratory symptoms usually start at birth. The lack of diagnostic gold standard tests is challenging, as PCD diagnostics requires different methods with high expertise. We founded PCD-UNIBE as the first comprehensive PCD diagnostic center in Switzerland. Our diagnostic approach includes nasal brushing and cell culture with analysis of ciliary motility via high-speed-videomicroscopy (HSVM) and immunofluorescence labeling (IF) of structural proteins. Selected patients undergo electron microscopy (TEM) of ciliary ultrastructure and genetics. We report here on the first 100 patients assessed by PCD-UNIBE. All patients received HSVM fresh, IF, and cell culture (success rate of 90%). We repeated the HSVM with cell cultures and conducted TEM in 30 patients and genetics in 31 patients. Results from cell cultures were much clearer compared to fresh samples. For 80 patients, we found no evidence of PCD, 17 were diagnosed with PCD, two remained inconclusive, and one case is ongoing. HSVM was diagnostic in 12, IF in 14, TEM in five and genetics in 11 cases. None of the methods was able to diagnose all 17 PCD cases, highlighting that a comprehensive approach is essential for an accurate diagnosis of PCD.

Higher throughput drug screening for rare respiratory diseases: readthrough therapy in primary ciliary dyskinesia.

BackgroundDevelopment of therapeutic approaches for rare respiratory diseases is hampered by the lack of systems that allow medium-to-high-throughput screening of fully differentiated respiratory epithelium from affected patients. This is a particular problem for primary ciliary dyskinesia (PCD), a rare genetic disease caused by mutations in genes that adversely affect ciliary movement and consequently mucociliary transport. Primary cell culture of basal epithelial cells from nasal brush biopsies followed by ciliated differentiation at the air–liquid interface (ALI) has proven to be a useful tool in PCD diagnostics but the technique's broader utility, including in pre-clinical PCD research, has been restricted by the limited number of basal cells that can be expanded from such biopsies.MethodsWe describe an immunofluorescence screening method, enabled by extensive expansion of basal cells from PCD patients and the directed differentiation of these cells into ciliated epithelium in miniaturised 96-well transwell format ALI cultures. As proof-of-principle, we performed a personalised investigation in a patient with a rare and severe form of PCD (reduced generation of motile cilia), in this case caused by a homozygous nonsense mutation in the MCIDAS gene.ResultsInitial analyses of ciliary ultrastructure, beat pattern and beat frequency in the 96-well transwell format ALI cultures indicate that a range of different PCD defects can be retained in these cultures. The screening system in our proof-of-principal investigation allowed drugs that induce translational readthrough to be evaluated alone or in combination with nonsense-mediated decay inhibitors. We observed restoration of basal body formation but not the generation of cilia in the patient's nasal epithelial cells in vitro.ConclusionOur study provides a platform for higher throughput analyses of airway epithelia that is applicable in a range of settings and suggests novel avenues for drug evaluation and development in PCD caused by nonsense mutations.

Accuracy of diagnostic testing in primary ciliary dyskinesia.

Diagnosis of primary ciliary dyskinesia (PCD) lacks a “gold standard” test and is therefore based on combinations of tests including nasal nitric oxide (nNO), high-speed video microscopy analysis (HSVMA), genotyping and transmission electron microscopy (TEM). There are few published data on the accuracy of this approach.Using prospectively collected data from 654 consecutive patients referred for PCD diagnostics we calculated sensitivity and specificity for individual and combination testing strategies. Not all patients underwent all tests.HSVMA had excellent sensitivity and specificity (100% and 93%, respectively). TEM was 100% specific, but 21% of PCD patients had normal ultrastructure. nNO (30 nL·min−1 cut-off) had good sensitivity and specificity (91% and 96%, respectively). Simultaneous testing using HSVMA and TEM was 100% sensitive and 92% specific.In conclusion, combination testing was found to be a highly accurate approach for diagnosing PCD. HSVMA alone has excellent accuracy, but requires significant expertise, and repeated sampling or cell culture is often needed. TEM alone is specific but misses 21% of cases. nNO (≤30 nL·min−1) contributes well to the diagnostic process. In isolation nNO screening at this cut-off would miss ∼10% of cases, but in combination with HSVMA could reduce unnecessary further testing. Standardisation of testing between centres is a future priority.

Ciliary beat pattern and frequency in genetic variants of primary ciliary dyskinesia.

Primary ciliary dyskinesia (PCD) is a rare genetic disorder leading to recurrent respiratory tract infections. High-speed video-microscopy analysis (HVMA) of ciliary beating, currently the first-line diagnostic tool for PCD in most centres, is challenging because recent studies have expanded the spectrum of HVMA findings in PCD from grossly abnormal to very subtle. The objective of this study was to describe the diversity of HVMA findings in genetically confirmed PCD individuals. HVMA was performed as part of the routine work-up of individuals with suspected PCD. Subsequent molecular analysis identified biallelic mutations in the PCD-related genes of 66 individuals. 1072 videos of these subjects were assessed for correlation with the genotype. Biallelic mutations (19 novel) were found in 17 genes: DNAI1, DNAI2, DNAH5, DNAH11, CCDC103, ARMC4, KTU/DNAAF2, LRRC50/DNAAF1, LRRC6, DYX1C1, ZMYND10, CCDC39, CCDC40, CCDC164, HYDIN, RSPH4A and RSPH1. Ciliary beat pattern variations correlated well with the genetic findings, allowing the classification of typical HVMA findings for different genetic groups. In contrast, analysis of ciliary beat frequency did not result in additional diagnostic impact. In conclusion, this study provides detailed knowledge about the diversity of HVMA findings in PCD and may therefore be seen as a guide to the improvement of PCD diagnostics.