Primary ciliary dyskinesia in pediatric persons: A microscopic movement malady.

Primary ciliary dyskinesia (PCD) is a rare hereditary disorder characterized by defective motile cilia and impaired mucociliary clearance in the respiratory tract. In recent years, significant advances have been made in both clinical and basic research on PCD, especially regarding the identification of newly discovered pathogenic genes. However, early diagnosis and treatment of PCD in China still face considerable challenges. In response, a new expert consensus on the diagnosis and treatment of PCD in China has been developed. This consensus was initiated by the Genetic and Rare Lung Disease Group (Preparatory) of the Chinese Thoracic Society of the Chinese Medical Association and the China Bronchiectasis Clinical Diagnosis and Research Alliance. This consensus is based on extensive opinion collection, literature review, online and offline discussions, and previous expert consensus on PCD in China. The consensus addresses 9 core issues related to PCD, including its clinical presentation, diagnosis, treatment, patient management, and follow-up. Nine recommendations have been formulated to improve the diagnostic and therapeutic approaches to PCD in China.Issue 1: Which high-risk populations should undergo PCD screening?Recommendation 1: It is recommended to screen for PCD in patients with a history of bronchiectasis plus any one of the following: situs inversus; chronic sinusitis or nasal polyps; recurrent or chronic otitis media; infertility/subfertility; consanguinity, or a sibling or first-degree relative with a confirmed PCD diagnosis (1C).Issue 2: What is the value of imaging examinations in the diagnosis and management of PCD?Recommendation 2: For the high-risk PCD populations mentioned above, we recommend performing active imaging investigations-including chest high-resolution computed tomography (HRCT), sinus CT, and cardiac ultrasonography-to aid in the early detection of clinical features indicative of PCD, such as bronchiectasis, sinusitis, and situs inversus. In addition, for patients diagnosed with PCD, we recommend regular follow-up chest HRCT to monitor the progression of pulmonary lesions (1C).Issue 3: What is the value of transmission electron microscopy (TEM) in diagnosing PCD?Recommendation 3: For patients with a high clinical suspicion of PCD, we recommend transmission electron microscopy (TEM) for the assessment of ciliary ultrastructure. TEM serves as a direct diagnostic tool for suspected PCD. A definitive diagnosis of PCD can be made if a class 1 defect is identified (1B). If a class 2 defect is observed, the results should be interpreted in conjunction with other diagnostic findings.Issue 4: What is the value of genetic testing in PCD diagnosis, and which genetic testing strategy should be used?Recommendation 4: For patients with a high clinical suspicion of PCD, we recommend performing genetic testing using whole-exome sequencing (WES) at an early stage. WES serves as a direct diagnostic tool for suspected PCD. A definitive diagnosis can be made when biallelic pathogenic or likely pathogenic variants in known PCD-related genes are identified. During WES data analysis, it is essential to include the assessment of copy number variations (CNVs) (1C).Issue 5: What is the value of nasal nitric oxide (nNO) measurement in diagnosing PCD?Recommendation 5: nNO measurement is recommended as an adjunctive diagnostic test for suspected PCD. Using a threshold of 77 nl/min, patients with nNO values below this threshold should undergo further confirmatory PCD testing (2B).Issue 6: What is the value of high-speed video microscopy analysis (HSVA) in diagnosing PCD?Recommendation 6: In clinical settings with access to HSVA, HSVA is recommended as an adjunctive diagnostic test for suspected PCD. A positive HSVA result warrants further confirmatory testing (2C).Issue 7: What is the value of immunofluorescence (IF) in diagnosing PCD?Recommendation 7: In clinical settings where IF is available, it can be recommended as an adjunctive diagnostic test for suspected PCD. A positive IF result warrants further confirmatory testing (2D).Issue 8: How should PCD patients be followed up?Recommendation 8: Regular annual follow-up is recommended for adult PCD patients. Key follow-up components include assessment of pulmonary, sinus, and otologic symptoms and function. Additional assessments should include evaluation of disease severity, immune status, quality of life, and psychological status. Furthermore, infertility/subfertility assessment and follow-up are recommended for PCD patients of reproductive age (1C).Issue 9: How can genetic counseling assist PCD patient families in reproductive planning and decision-making?Recommendation 9: Providing appropriate genetic counselling to families of PCD patients can help identify carriers and assess the risk of offspring having PCD for individuals of reproductive age, thereby assisting them in making informed reproductive decisions (1D).

Sir, Primary ciliary dyskinesia (PCD) is a rare autosomal recessive condition affecting the structure and function of motile cilia, thereby resulting in impairment of mucociliary clearance.[1] The common manifestations in children include neonatal respiratory distress, early-onset chronic wet cough, and recurrent respiratory infections, leading to bronchiectasis, recurrent rhinosinusitis, and middle ear infections.[1] Around one-half of PCD patients have dextrocardia and/or situs inversus totalis.[2] In the reproductive age group, PCD can be associated with male infertility and subfertility in females.[1] Diagnosis of PCD involves identification of the clinical phenotype and a combination of tests that require expertise to conduct and interpret the results.[3] The upfront screening tests are nasal nitric oxide measurement and high-speed video microscopy of nasal brushings for ciliary beat pattern and frequency [Figure 1].[3] Hallmark ciliary ultrastructure abnormalities and/or bi-allelic disease-causing mutations in known PCD genes would be diagnostic.[3] PCD can occur in the presence of normal ciliary ultrastructure, and at present, genetic testing can identify mutations in more than 80% of PCD patients.[4] Due to lack of awareness among clinicians and nonavailability of diagnostic tests, PCD is underdiagnosed and the exact frequency of PCD in India is still not known. We report a 14-year-old boy with PCD due to DRC1/CCDC164 mutation for the first time from the Indian subcontinent.Figure 1: High-speed video microscopyA 14-years-old boy, born to nonconsanguineous parents, presented to us with purulent nasal discharge, persistent productive cough, and recurrent respiratory infections with wheeze since infancy. He was born at term and did not have respiratory distress in the neonatal period. His weight and height were on the third centile. He had purulent nasal discharge and auscultation of his chest revealed bilateral crackles and wheeze. High-resolution chest tomography revealed right upper lobe collapse and centrilobular opacities. Sweat chloride estimation and serum immunoglobulin profile were within normal limits. Primary ciliary dyskinesia rule,[5] a predictive score with seven simple questions to predict the likelihood of having PCD, was 4, i.e., the likelihood of PCD was not high. Nasal nitric oxide analysis using portable electrochemical device, NIOX VERO®(Circassia, Sweden), was very low at 11.6 ppb (3.5 nl/min). High-speed video microscopy analysis (HSVA) of nasal brushings revealed motile cilia with stiff motility (reducing bending capacity) and a ciliary beat frequency of 14 Hz. The HSVA videos were reviewed by PCD team, Southampton University Hospital, UK. EDTA peripheral blood sample was sent for targeted next-generation targeted sequencing of the genes known to be associated with PCD. A homozygous nonsense variation in exon 10 of the DRC1 gene (chr2:26667625G>A; depth: 70x) that results in a stop codon and premature truncation of the protein at codon 402 (p. Trp402Ter; ENST00000288710.2) was detected. He is being managed by a multidisciplinary team and is under follow-up. PCD can be caused by bi-allelic mutations in the DRC1/CCDC164 gene.[6] This disorder characteristically starts in infancy with chronic sinopulmonary infections due to abnormal ciliary function.[6] The available literature shows that individuals with DRC1/CCDC164 mutations do not have any abnormal left–right body symmetry.[6] Our patient did not have any left–right body asymmetry. HSVA from our patient showed uniformly stiff cilia. These findings are similar to previous reports in PCD with documented DRC1/CCDC164 mutation.[6] We did not perform transmission electron microscopy due to lack of this facility at our center. PCD with normal body symmetry makes diagnosis even more difficult and late. When there is a strong suspicion based on other clinical features, we should proceed with diagnostic testing for PCD. Early diagnosis of PCD and prompt intervention have the potential to stall the progression of disease. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Dr. Antony Terance Benjamin received NIOX VERO® equipment as a research grant from Circassia, Sweden. Conflicts of interest There are no conflicts of interest. Acknowledgments We would like to acknowledge Dr. Louis Balan, Molecular Pathologist, Coimbatore, India, Dr. Janice Coles, PCD Diagnostic Service, University Hospital Southampton, UK, and Medgenome Labs, Bangalore, India.

Introduction: Primary Ciliary Dyskinesia (PCD) is a rare, genetically heterogenous disorder leading to recurrent respiratory tract infections due to abnormal ciliary motility causing impaired mucociliary clearance. High-speed videomicroscopy analysis (HVMA) of ciliary beat pattern (CBP) and frequency as the current first-line diagnostic tool is an increasing challenge, because current studies widely expended the spectrum of HVMA findings from very subtle to markedly abnormal. Objectives: We assigned typical HVMA findings to genetically confirmed PCD individuals in order to identify typical patterns for various PCD variants. Methods: We assessed 1072 videos from nasal brush biopsies of 66 PCD individuals by HVMA as part of routine diagnostic work-up. HVMA findings were subsequently correlated with the genotype (biallelic mutations in 17 genes). Results: Distinct CBP correlated well with genetic findings, which allows the classification of typical HVMA findings for various genetic groups: Respiratory cilia with outer dynein arm defects (ODA) showed minimal residual movements with a minority of cilia being completely immotile. Cilia with combined inner (IDA) and ODA defects were completely immotile. Defects of the central pair apparatus resulted in a rigid and uncoordinated CBP. Combined IDA and microtubular disorganization defects resulted in a hyperkinetic, very stiff and vibratory CBP. Nexin link defects showed an almost regular CBP with only slightly reduced beating amplitude. Conclusion: This study improves clinical PCD diagnostics by classifying different PCD subtypes using HVMA as the first-line diagnostic tool and facilitates the subsequent diagnostics.

Primary ciliary dyskinesia (PCD) is a rare ciliopathy resulting in chronic oto-sino-pulmonary disease. PCD diagnosis can be achieved by a combination of different diagnostic and adjuvant tools, including high-speed video-microscopy analysis (HSVA). A founder variant has been described in Puerto Rico as the most common cause of PCD in the island. Background/Objectives: In HSVA, objective parameters such as ciliary beat frequency (CBF) and subjective parameters such as ciliary beat pattern (CBP) shed light on the biophysical properties of cilia. However, the subjective nature of CBP creates a gap in knowledge; characteristics such as the length, angle, and bending index of cilia are poorly described. Our goal is to quantify cilia dynamics of the RSPH4A (c.921+3_921+6delAAGT (intronic)) founder variant in Puerto Rico through biophysical properties of cilia. This approach enhances longitudinal patient care by understanding treatment progress through biophysical ciliary function. Methods: We analyzed images from HSVA of six patients with PCD homozygous for the founder variant and six healthy controls (HC) (n = 12). Results: We found that ciliary length (PCD = 7.62 ± 0.95 μm, HC = 8.12 ± 1.36 μm, p = 0.204 ns), orientation vector (PCD = 7.20 ± 0.93 μm, HC = 7.25 ± 1.01 μm, p = 0.883 ns), straight angle (PCD = 1.67 ± 0.27 rad, HC = 1.76 ± 0.29 rad, p = 0.380 ns), and area (PCD = 2.35 ± 0.52 μm2, HC = 2.10 ± 0.53 μm2, p = 0.264 ns) did not have statistically significant differences between PCD and HC. In contrast, bending index (PCD = 1.06 ± 0.04, HC = 1.12 ± 0.09, p = 0.01), bent angle (PCD = 1.11 ± 0.30 rad, HC = 0.67 ± 0.21 rad, p < 0.0001), net angle (PCD = 0.56 ± 0.26 rad, HC = 1.09 ± 0.35 rad, p < 0.0001), amplitude (PCD = 5.77 ± 1.25 μm, HC = 7.99 ± 1.65 μm, p < 0.0001), and amplitude per second (PCD = 48.83 ± 13.23 A(s), HC = 91.66 ± 27.96 A(s), p < 0.0001) showed significant differences between both groups. Conclusions: Reduced angular excursion and amplitude in PCD demonstrate that the beating pattern of the RSPH4A founder variant is dysfunctional as compared with healthy controls. Our study provides an objective framework to understand the biophysical properties of the RSPH4A founder variant.

Implementation of a screening tool for primary ciliary dyskinesia (PCD) in a pediatric otolaryngology clinic

Robust diagnosis of primary ciliary dyskinesia (PCD) is important if patients are to receive appropriate specialist management before irreversible deterioration of lung function occurs. Early diagnosis also enables patients and their families to receive appropriate genetic counseling, disease-specific management of ear and rhino-sinus disease, and screening for PCD-associated problems (e.g., cardiac problems) (1, 2). The association of extremely low levels of nasal nitric oxide (nNO) in PCD has been recognized for over 15 years, and measurement of nNO is increasingly used as a screening test for PCD in Europe (1). The manuscript by Leigh and coworkers in this edition of AnnalsATS (3) provides an important advance in the use of nNO for clinical and research purposes. Their data confirm that nNO is a reliable investigation for PCD in the North American population and setting, including identification of “atypical” patients with PCD who might otherwise be missed due to normal ciliary ultrastructure. The authors provide evidence that a standardized protocol using different NO analyzers can be used to reliably differentiate patients with PCD from patients without PCD and from healthy children, in geographically dispersed centers. They have additionally developed cutoff values using data from their large study population, which can now be validated in other populations. There is no “gold standard” diagnostic test to identify all PCD phenotypes, and diagnostic workup requires access to a number of specialist investigations. Previously, ciliary ultrastructure analyzed by electron microscopy (EM) was considered diagnostic, but there is an increasing literature on normal ciliary ultrastructure, at EM resolution, in PCD. This indicates that PCD will be missed in centers where diagnosis depends solely on EM (2, 4). It is also recognized that certain EM defects previously considered diagnostic might on occasion represent secondary changes that resolve on repeat testing (4, 5). In Europe, assessment of ciliary beat frequency (CBF) and pattern (CBP) by high-resolution, high-speed video microscopy (HSVm) is recommended as a functional test for PCD (1, 6). If HSVm analysis is abnormal, re-differentiation of basal epithelial cells at an air–liquid interface (ALI) in cell culture enables reassessment of ciliary function and ultrastructure to differentiate primary from secondary dyskinesia (1). Alternatively, immunoflorescent (IF) staining of ciliary proteins can support diagnosis of PCD (7). EM, HSVm, ALI-culture, and IF all require a high degree of expertise in addition to expensive equipment and infrastructure. These techniques are therefore restricted to a few highly specialized centers, limiting easy access to diagnostic testing (8). Diagnosis supported by bi-allelic mutations in genes known to be associated with PCD is promising; currently genotyping detects only 50–65% of patients (2), but as new genes are rapidly identified this will become increasingly sensitive. The evidence provided by Leigh and coleagues (3) is therefore to be welcomed by clinicians, researchers, and in particular families who are unable to travel to a highly specialized center. It is to be hoped that the U.S. Food and Drug Administration and other regulatory authorities will approve nNO analyzers for clinical use given the evidence that nNO is a reliable screening test for PCD and that valid measurements can be taken at sites geographically distant from a diagnostic center using standardized protocols. Leigh and coworkers report a cutoff value for nNO of 77 nL/min providing sensitivity of 0.98 and specificity greater than 0.999. This cutoff value was validated across six other sites, identifying 70 of the 71 (98.6%) participants with confirmed PCD. A previous study used a cutoff for nNO of 105 parts per billion and reported a specificity of 88%, a sensitivity of 100%, and a positive predictive value of 89% for correctly diagnosing PCD (9). While there are now substantial data to demonstrate that nNO measurement is helpful in guiding the diagnostic pathway, we need to recognize limitations of this measurement. Standardized methods (10) to measure nNO are not appropriate for younger children, precisely the age group that need targeting for diagnostic measurement. Tidal measurements allow levels to be measured in young infants, although there is limited experience in this younger age group (1, 11, 12). Patients with other with upper and lower airway diseases have been reported to have reduced nNO levels, although usually not as low as in PCD; such diseases include cystic fibrosis, nasal polyps and chronic sinusitis. A few groups have recently reported normal levels of nasal NO in a minority of patients with PCD (1, 11, 13). These studies highlight that patients with a history strongly suggestive of PCD should not be excluded from further diagnostic evaluation on the basis of nNO, and also that, while providing an excellent screening test, nNO is not diagnostic and low levels should trigger referral to a highly specialized diagnostic center. A priority for researchers is to understand the cause of the extraordinarily low nNO observed in PCD (14). From a clinical perspective, the next hurdle to overcome is the lack of regulatory approvals of nNO analyzers for PCD diagnosis, as well as the cost and therefore availability of devices. Until recently, the only commercially available analyzers for measuring nNO were nonportable desktop analyzers, which are extremely expensive. More reasonably priced portable machines (15) are now available, although they are not yet fully validated nor approved for clinical use. Manufacturers should be encouraged to develop, validate, and seek approvals for user-friendly, reasonably priced nNO analyzers. This will lead to a step change in the diagnosis of PCD by reliably identifying patients for referral to specialist diagnostic centers.

Primary Ciliary Dyskinesia and Cystic Fibrosis: Different Diseases Require Different Treatment

ABSTRACTBackground and Objective:To screen patients with suspected primary ciliary dyskinesia (PCD) using high-speed video microscopy analysis (HSVA) and/or nasal nitric oxide (nNO) through an international collaborative initiative between GKNM Hospital, Coimbatore, India, and the PCD Centre, University Hospital Southampton, UK.Methods:Children and adults up to 30 years of age with clinical features suggestive of PCD were recruited. HSVA was performed on nasal brushing biopsies for all participants. Nasal NO was measured, when feasible, in patients aged ≥5 years using a portable electrochemical NIOX VERO® device. Online multidisciplinary team meetings involving both centres reviewed and interpreted the results. Patients who tested positive on at least one of the two screening tests were classified as PCD screen-positive. Due to resource constraints, only a subset of screen-positive patients underwent genetic testing.Results:Among the 113 patients screened, 68 (60.1%) were PCD screen-positive. Next-generation sequencing was performed in 26 of these 68 patients, and PCD was genetically confirmed in 14 cases. The median age at diagnosis was 8.5 years.Conclusion:In resource-limited settings, diagnosis of PCD is often delayed. A combined screening strategy using HSVA and nasal NO testing can help identify likely PCD cases and facilitate early intervention. HSVA and nNO testing were found to be complementary in the screening of PCD. Genetic testing was used in a subset of patients to confirm diagnosis and was conclusive in 54% of tested.

Primary ciliary dyskinesia (PCD) is a rare genetic disorder characterized by impaired function of the ciliated epithelium. Ciliary dysfunction leads to chronic respiratory tract infections, bronchiectasis, sinusitis, and sometimes organ laterality defects (Kartagener syndrome). Diagnosis requires an analysis of clinical manifestations, measurement of nasal nitric oxide (nNO) levels, assessment of ciliary function and structure using high-speed video microscopy analysis (HSVA) and transmission electron microscopy (TEM), as well as genetic testing. Diagnosing PCD is complicated by cases with normal ciliary ultrastructure, difficulties in differentiating PCD from secondary ciliary dyskinesia, and the genetic heterogeneity of the disease. The HSVA method enables rapid evaluation of key ciliary function parameters, including ciliary beat frequency and ciliary beat pattern, making it one of the cornerstone tools in diagnosing PCD. The aim of this study was to review the HSVA method and software tools designed for the automated processing of HSVA results in PCD diagnostics. Results. The review identified 13 main software tools. The findings show that these tools provide accuracy comparable to manual analysis, facilitate data processing, and reduce the influence of human error. However, manual analysis remains predominant due to the limited availability and complexity of automated solutions. To improve diagnostic quality, further development of universal and accessible software solutions is needed, along with the standardization of HSVA data analysis approaches. Conclusion. HSVA is a pivotal diagnostic method for PCD, which evaluates the function of cilia. HSVA in combination with genetic testing and TEM has been demonstrated to facilitate the identification of the disease. The automation and standardization of HSVA, including the use of video image analysis software for ciliated epithelium, enhance the quality of diagnosis.

RATIONALE: Primary Ciliary Dyskinesia (PCD), a genetic disorder of motile cilia, is associated with a range of clinical features including neonatal respiratory distress, chronic sino-oto-pulmonary disease, and laterality defects, including situs inversus totalis (approximately 50%) and heterotaxy (at least 6%). Heterotaxy is a disorder of ambiguous organ laterality frequently associated with congenital heart disease. Clinical symptoms in PCD can overlap with symptoms from congenital heart disease with heterotaxy. Nasal nitric oxide (nNO) levels are very low in PCD, but have not been studied systematically in heterotaxy. PCD-specific symptom criteria and nNO cut-off levels would help guide appropriate PCD screening within heterotaxy populations. METHODS: Two heterotaxy populations (age ≥5 years) were recruited. First, our multi-center consortium assessed individuals referred for suspected PCD due to sino-oto-pulmonary symptoms, including participants with heterotaxy. Second, one site (UNC) evaluated heterotaxy individuals followed in a cardiology clinic and never referred for suspected PCD. Both populations were investigated with symptom questionnaires and nNO measurements during palate closure. Those referred for suspected PCD also had electron microscopy (EM) of nasal cilia and genetic testing for PCD mutations. “Classic PCD” was diagnosed in participants with classic EM cilia defects and/or 2 PCD causing genetic mutations. Otherwise, participants were classified as “not classic PCD” and stratified by nNO level – those with nNO 100nL/min. RESULTS: Of 336 individuals referred for PCD symptoms, 30 (8.9%) have heterotaxy, including 15 with congenital heart disease. 15/30 have “classic PCD” and all of these have nNO 100nL/min (median 280; 137-338nL/min). The 12 cardiology clinic patients all have nNO >100nL/min (median 199; 127-287nL/min). Clinical features more prevalent in heterotaxy with “classic PCD” versus heterotaxy with nNO >100nl/min are: year-round wet cough (100% versus 26%, p<0.0001), year-round nasal congestion (93% versus 42%, p=0.001), bronchitis/pneumonia (93% versus 47%, p=0.003), recurrent otitis media (87% versus 53%, p=0.02), and chronic sinusitis (73% vs 37%, p=0.03). No significant differences were noted for clinical features in heterotaxy with “classic PCD” versus with low nNO levels. CONCLUSION: In heterotaxy, PCD-specific clinical features include year-round wet cough, year-round nasal congestion, bronchitis/pneumonia, otitis media, and sinusitis. nNO seems a sensitive screening test for PCD within heterotaxy. Presence of PCD specific clinical features and/or low nNO should prompt further PCD evaluation.

Primary ciliary dyskinesia (PCD), a rare disorder, is genetically varied. Mutations in proteins involved in the structure, function, or assembly of cilia are known to determine situs inversus, male infertility, and chronic destructive airway disease. PCD is inherited by an autosomal recessive pattern of inheritance in most cases. Nonetheless, patterns of autosomal dominant and X-linked inheritance have been mentioned. A history of recurrent upper and lower respiratory tract infections raised clinical suspicion of primary ciliary dyskinesia in a 10-year-old patient. Genetic tests were performed using next-generation sequencing technology (Illumina NextGen) with the multiplex ligation-dependent probe amplification technique for primary ciliopathies and syndromes subject to differential diagnosis. Genetic testing identified two pathogenic variants, not previously associated with a case report in the literature, c.7727A>G (p.Asp2576Gly) and c.8578G>A (p.Gly2860Ser), within the DNAH11 gene, which is associated with autosomal recessive PCD. The result also reported mutations in other genes involved in autosomal recessive PCD (DNAH8, DNAH9 and ZMYND10), which were classified as variants with uncertain clinical significance. Transmission electron microscopy of respiratory cilia and nasal nitric oxide measurement cannot be used to diagnose PCD in patients with DNAH11 mutations because the structure of cilia is normal, and the levels of NO are not constantly low. High-speed video microscopy analysis can be helpful because DNAH11 mutations cause a distinct phenotype of PCD. Nevertheless, the mutation analysis of various PCD-causing genes remains the easiest to conduct and with good results. Genetic research on PCD has identified a number of significant ciliary genes in recent years, offering fresh perspectives on the molecular processes underlying cilia assembly and function. This facilitates the development of new methods for the diagnosis, prevention, and treatment of PCD. However, because it is a highly complex and heterogeneous disease, the field of gene diagnosis and therapy in PCD is still in its infancy.

Primary ciliary dyskinesia (PCD) is a rare disorder of the mucociliary clearance leading to recurrent upper and lower respiratory tract infections. PCD is difficult to clinically distinguish from other entities leading to recurrent oto-sino-pulmonary infections, including primary immunodeficiency (PID). Nasal nitric oxide (nNO) is a sensitive and specific diagnostic test for PCD, but it has not been thoroughly examined in PID. Past publications have suggested an overlap in nNO levels among subjects with PCD and PID. We sought to determine if nNO measurements among patients diagnosed with PID would fall significantly above the established PCD diagnostic cutoff value of 77nL/min. Children > 5years old and adults with definitive PID or PCD diagnoses were recruited from outpatient subspecialty clinics. Participants underwent nNO testing by standardized protocol using a chemiluminescence analyzer and completed a questionnaire concerning their chronic oto-sino-pulmonary symptoms, including key clinical criteria specific to diagnosed PCD (neonatal respiratory distress at term birth, year-round cough or nasal congestion starting before 6months of age, any organ laterality defect). Participants included 32 patients with PID, 27 patients with PCD, and 19 healthy controls. Median nNO was 228.9.1nL/min in the PID group, 19.7nL/min in the PCD group, and 269.4 in the healthy controls (p < 0.0001). Subjects with PCD were significantly more likely to report key clinical criteria specific to PCD, but approximately 25% of PID subjects also reported at least 1 of these key clinical criteria (mainly year-round cough or nasal congestion). While key clinical criteria associated with PCD often overlap with the symptoms reported in PID, nNO measurement by chemiluminescence technology allows for effective discrimination between PID and PCD.

Introduction: In primary ciliary dyskinesia there is an alteration of ciliary beat frequency and/or ciliary beat pattern. Aims and objectives: The aim of this preliminary study was to assess the ciliary beat frequency in patients affected of respiratory illnesses that could be present in primary ciliary dyskinesia. Methods: Nasal nitric oxide (nNO) was measured in 20 patients affected of respiratory illnesses in whom primary ciliary dyskinesia was suspected. Ciliated epithelium was obtained by brushing the inferior nasal turbinate. Beat frequency measurements were made by digital high speed video analysis. Abnormal beat pattern was considered when less than 80% of the measurements were normal beat pattern. Circular, static, rigid and dyskinetic (flickering or others) patterns were considered as abnormal patterns. Results: Twenty patients (2-55 years-old) were studied. Newborn respiratory distress was present in 4 patients, bronchiectasis (10), recurrent otitis media (10), sinusitis (5), middle lobe syndrome (2), recurrent pneumonia (7), gastro-esophageal reflux (3). Nasal nitric oxide ranged from 44 ppb to 1019 ppb. Beat frequency ranged from 7,26 Hz to 14,46 Hz. Static beat pattern was predominant in 8 patients, dyskinetic beat pattern in 2 patients and circular beat pattern in one patient. In one patient there were no cilia. In all patients with beat frequency below 8,5 Hz, beat pattern were abnormal. There was an overlap on beat frequency values in patients with normal and abnormal beat pattern. Conclusions: In this study, similar ciliary beat frequencies were found in patients with normal and abnormal beat patterns. Genetic study or cell culture could help to differentiate between primary and secondary ciliary dyskinesia.

RATIONALE: Primary Ciliary Dyskinesia (PCD) is a rare ciliopathy resulting in chronic oto-sino-pulmonary disease. PCD diagnosis can be achieved by a combination of different diagnostic tools including high-speed video-microscopy analysis (HSVA). A founder mutation has been described in Puerto Rican as the most common cause of PCD in the island. In HSVA, objective parameters such as ciliary beat frequency (CBF) and subjective parameters such as ciliary beat pattern (CBP) shed light on the physical properties of cilia. However, the subjective nature of CBP creates a gap of knowledge; characteristics such as the length, angle, and bending index of cilia are poorly described. Our goal is to understand ciliary dynamics of the RSPH4A (c.921+3_921+6delAAGT (intronic)) founder mutation in Puerto Rico through physical properties of cilia. METHODS: We conducted a retrospective analysis of videos taken using HSVA on cases and controls. Each representative video pertained to one participant of the study. Six videos were of Healthy Controls (HC) and six videos were of patients with PCD with the RSPH4A (c.921+3_921+6delAAGT (intronic)) founder mutation (n=12). FIJI software was used to manually quantify ciliary measurements from HSVA videos, providing precise data on parameters such as length, angle, and other physical characteristics for comparative analysis. RESULTS: We found that ciliary length (p = 0.204), orientation vector (p = 0.883), straight angle (p = 0.380), and area (p = 0.264) did not have statistically significant differences between PCD and HC. In contrast, bending index (p = 0.01[asterisk]), bent angle (p &amp;lt; 0.0001[asterisk][asterisk][asterisk][asterisk]), net angle (p &amp;lt; 0.0001[asterisk][asterisk][asterisk][asterisk]), amplitude (p &amp;lt; 0.0001[asterisk][asterisk][asterisk][asterisk]), and amplitude per second (p &amp;lt; 0.0001[asterisk][asterisk][asterisk][asterisk]) showed significant differences between both groups. CONCLUSIONS: Shorter angle and amplitude in PCD are characteristics altered in the beating pattern of the RSPH4A founder mutation. Our study provides an objective way to understand the physical properties of the Puerto Rican founder mutation. This study is a step forward in developing a standardized, quantitative assessment for ciliary dysfunction in PCD. Further studies involving larger sample sizes and more advanced imaging techniques are necessary to deepen our understanding of these physical parameters and their implications for clinical outcomes.

BackgroundThe mutations in the RPGR (retinitis pigmentosa GTPase regulator) gene are the most common cause of X-linked retinitis pigmentosa (XLRP), a rare genetic disorder affecting the photoreceptor cells in the retina. Several reported cases identified this gene as a genetic link between retinitis pigmentosa (RP) and primary ciliary dyskinesia (PCD), characterised by impaired ciliary function predominantly in the respiratory tract. Since different mutations in the same gene can result in various clinical manifestations, it is important to describe a correlation between the gene variant and the observed phenotype.MethodsTwo young brothers from a non-consanguineous Slovak family with diagnosed retinal dystrophy and recurrent respiratory infections were examined. Suspected PCD was diagnosed based on a PICADAR questionnaire, nasal nitric oxide analysis, transmission electron microscopy, high-speed video microscopy analysis, and genetic testing.ResultsWe identified a novel frameshift RPGR mutation NM_001034853: c.309_310insA, p.Glu104Argfs*12, resulting in a complex X-linked phenotype combining PCD and RP. In our patients, this mutation was associated with normal ultrastructure of respiratory cilia, reduced ciliary epithelium, more aciliary respiratory epithelium, shorter cilia, and uncoordinated beating with a frequency at a lower limit of normal beating, explaining the clinical manifestation of PCD in our patients.ConclusionThe identified novel pathogenic mutation in the RPGR gene expands the spectrum of genetic variants associated with the X-linked PCD phenotype overlapping with RP, highlighting the diversity of mutations contributing to the disorder. The described genotype–phenotype correlation can be useful in clinical practice to recognise a broader spectrum of PCD phenotypes as well as for future research focused on the genetic basis of PCD, gene interactions, the pathways implicated in PCD pathogenesis, and the role of RPGR protein for the proper functioning of cilia in various tissues throughout the body.