High prevalence of primary ciliary dyskinesia in a British Asian population

Clinical care for primary ciliary dyskinesia: current challenges and future directions

Primary ciliary dyskinesia (PCD) is a rare genetic disease that affects the motility of cilia, leading to impaired mucociliary clearance. It is estimated that the vast majority of patients with PCD have not been diagnosed as such, providing a major obstacle to delivering appropriate care. Challenges in diagnosing PCD include lack of disease-specific symptoms and absence of a single, "gold standard", diagnostic test. Management of patients is currently not based on high-level evidence because research findings are mostly derived from small observational studies with limited follow-up period. In this review, we provide a critical overview of the available literature on clinical care for PCD patients, including recent advances. We identify barriers to PCD research and make suggestions for overcoming challenges.

Primary ciliary dyskinesia: mechanisms and management

Primary ciliary dyskinesia is a genetically heterogeneous disorder of motile cilia that is predominantly inherited in an autosomal-recessive fashion. It is associated with abnormal ciliary structure and/or function leading to chronic upper and lower respiratory tract infections, male infertility, and situs inversus. The estimated prevalence of primary ciliary dyskinesia is approximately one in 10,000-40,000 live births. Diagnosis depends on clinical presentation, nasal nitric oxide, high-speed video-microscopy analysis, transmission electron microscopy, genetic testing, and immunofluorescence. Here, we review its clinical features, diagnostic methods, molecular basis, and available therapies.

Diagnosis of primary ciliary dyskinesia: summary of the ERS Task Force report

Key points

Primary ciliary dyskinesia (PCD) is a genetically and clinically heterogeneous disease characterised by abnormal motile ciliary function.

There is no “gold standard” diagnostic test for PCD.

The European Respiratory Society (ERS) Task Force Guidelines for diagnosing PCD recommend that patients should be referred for diagnostic testing if they have several of the following features: persistent wet cough; situs anomalies; congenital cardiac defects; persistent rhinitis; chronic middle ear disease with or without hearing loss; or a history, in term infants, of neonatal upper and lower respiratory symptoms or neonatal intensive care admission.

The ERS Task Force recommends that patients should be investigated in a specialist PCD centre with access to a range of complementary tests: nasal nitric oxide, high-speed video microscopy analysis and transmission electron microscopy. Additional tests including immunofluorescence labelling of ciliary proteins and genetic testing may also help determine the diagnosis.

Educational aims

This article is intended for primary and secondary care physicians interested in primary ciliary dyskinesia (PCD), i.e. those who identify patients for testing, and those involved in diagnosing and managing PCD patients. It aims:

to inform readers about the new European Respiratory Society Task Force Guidelines for diagnosing patients with PCD

to enable primary and secondary care physicians to: identify patients who need diagnostic testing; understand the diagnostic tests that their patients will undergo, the results of the tests and their limitations; and ensure that appropriate care is subsequently delivered.

What primary and secondary care physicians should know about the diagnosis of primary ciliary dyskinesiahttp://ow.ly/obix30drts1

High prevalence of CCDC103 p.His154Pro mutation causing primary ciliary dyskinesia disrupts protein oligomerisation and is associated with normal diagnostic investigations

RATIONALE

Primary ciliary dyskinesia is a genetically heterogeneous inherited condition characterised by progressive lung disease arising from abnormal cilia function. Approximately half of patients have situs inversus. The estimated prevalence of primary ciliary dyskinesia in the UK South Asian population is 1:2265. Early, accurate diagnosis is key to implementing appropriate management but clinical diagnostic tests can be equivocal.

OBJECTIVES

To determine the importance of genetic screening for primary ciliary dyskinesia in a UK South Asian population with a typical clinical phenotype, where standard testing is inconclusive.

METHODS

Next-generation sequencing was used to screen 86 South Asian patients who had a clinical history consistent with primary ciliary dyskinesia. The effect of a CCDC103 p.His154Pro missense variant compared with other dynein arm-associated gene mutations on diagnostic/phenotypic variability was tested. CCDC103 p.His154Pro variant pathogenicity was assessed by oligomerisation assay.

RESULTS

Sixteen of 86 (19%) patients carried a homozygous CCDC103 p.His154Pro mutation which was found to disrupt protein oligomerisation. Variable diagnostic test results were obtained including normal nasal nitric oxide levels, normal ciliary beat pattern and frequency and a spectrum of partial and normal dynein arm retention. Fifteen (94%) patients or their sibling(s) had situs inversus suggesting CCDC103 p.His154Pro patients without situs inversus are missed.

CONCLUSIONS

The CCDC103 p.His154Pro mutation is more prevalent than previously thought in the South Asian community and causes primary ciliary dyskinesia that can be difficult to diagnose using pathology-based clinical tests. Genetic testing is critical when there is a strong clinical phenotype with inconclusive standard diagnostic tests.

Primary Ciliary Dyskinesia: An Update on Clinical Aspects, Genetics, Diagnosis, and Future Treatment Strategies

Primary ciliary dyskinesia (PCD) is an orphan disease (MIM 244400), autosomal recessive inherited, characterized by motile ciliary dysfunction. The estimated prevalence of PCD is 1:10,000 to 1:20,000 live-born children, but true prevalence could be even higher. PCD is characterized by chronic upper and lower respiratory tract disease, infertility/ectopic pregnancy, and situs anomalies, that occur in ≈50% of PCD patients (Kartagener syndrome), and these may be associated with congenital heart abnormalities. Most patients report a daily year-round wet cough or nose congestion starting in the first year of life. Daily wet cough, associated with recurrent infections exacerbations, results in the development of chronic suppurative lung disease, with localized-to-diffuse bronchiectasis. No diagnostic test is perfect for confirming PCD. Diagnosis can be challenging and relies on a combination of clinical data, nasal nitric oxide levels plus cilia ultrastructure and function analysis. Adjunctive tests include genetic analysis and repeated tests in ciliary culture specimens. There are currently 33 known genes associated with PCD and correlations between genotype and ultrastructural defects have been increasingly demonstrated. Comprehensive genetic testing may hopefully screen young infants before symptoms occur, thus improving survival. Recent surprising advances in PCD genetic designed a novel approach called "gene editing" to restore gene function and normalize ciliary motility, opening up new avenues for treating PCD. Currently, there are no data from randomized clinical trials to support any specific treatment, thus, management strategies are usually extrapolated from cystic fibrosis. The goal of treatment is to prevent exacerbations, slowing the progression of lung disease. The therapeutic mainstay includes airway clearance maneuvers mainly with nebulized hypertonic saline and chest physiotherapy, and prompt and aggressive administration of antibiotics. Standardized care at specialized centers using a multidisciplinary approach that imposes surveillance of lung function and of airway biofilm composition likely improves patients' outcome. Pediatricians, neonatologists, pulmonologists, and ENT surgeons should maintain high awareness of PCD and refer patients to the specialized center before sustained irreversible lung damage develops. The recent creation of a network of PCD clinical centers, focusing on improving diagnosis and treatment, will hopefully help to improve care and knowledge of PCD patients.

Diagnosis of primary ciliary dyskinesia: potential options for resource-limited countries

Primary ciliary dyskinesia is a genetic disease of ciliary function leading to chronic upper and lower respiratory tract symptoms. The diagnosis is frequently overlooked because the symptoms are nonspecific and the knowledge about the disease in the primary care setting is poor. Additionally, none of the available tests is accurate enough to be used in isolation. These tests are expensive, and need sophisticated equipment and expertise to analyse and interpret results; diagnosis is therefore only available at highly specialised centres. The diagnosis is particularly challenging in countries with limited resources due to the lack of such costly equipment and expertise.

In this review, we discuss the importance of early and accurate diagnosis especially for countries where the disease is clinically prevalent but diagnostic tests are lacking. We review the diagnostic tests available in specialised centres (nasal nitric oxide, high-speed video microscopy, transmission electron microscopy, immunofluorescence and genetics). We then consider modifications that might be considered in less well-resourced countries whilst maintaining acceptable accuracy.

Clinical manifestations in primary ciliary dyskinesia: systematic review and meta-analysis

Few original studies have described the prevalence and severity of clinical symptoms of primary ciliary dyskinesia (PCD). This systematic review and meta-analysis aimed to identify all published studies on clinical manifestations of PCD patients, and to describe their prevalence and severity stratified by age and sex.We searched PubMed, Embase and Scopus for studies describing clinical symptoms of ≥10 patients with PCD. We performed meta-analyses and meta-regression to explain heterogeneity.We included 52 studies describing a total of 1970 patients (range 10-168 per study). We found a prevalence of 5% for congenital heart disease. For the rest of reported characteristics, we found considerable heterogeneity (I² range 68-93.8%) when calculating the weighted mean prevalence. Even after taking into account the explanatory factors, the largest part of the between-studies variance in symptom prevalence remained unexplained for all symptoms. Sensitivity analysis including only studies with test-proven diagnosis showed similar results in prevalence and heterogeneity.Large differences in study design, selection of study populations and definition of symptoms could explain the heterogeneity in symptom prevalence. To better characterise the disease, we need larger, multicentre, multidisciplinary, prospective studies that include all age groups, use uniform diagnostics and report on all symptoms.

Diagnosing primary ciliary dyskinesia: an international patient perspective

Primary ciliary dyskinesia (PCD) is a rare genetic disorder characterised by progressive sino-pulmonary disease, with symptoms starting soon after birth. A European Respiratory Society (ERS) Task Force aims to address disparities in diagnostics across Europe by providing evidence-based clinical practice guidelines. We aimed to identify challenges faced by patients when referred for PCD diagnostic testing.

A patient survey was developed by patient representatives and healthcare specialists to capture experience. Online versions of the survey were translated into nine languages and completed in 25 countries. Of the respondents (n=365), 74% were PCD-positive, 5% PCD-negative and 21% PCD-uncertain/inconclusive. We then interviewed 20 parents/patients. Transcripts were analysed thematically.

35% of respondents visited their doctor more than 40 times with PCD-related symptoms prior to diagnostic referral. Furthermore, the most prominent theme among interviewees was a lack of PCD awareness among medical practitioners and failure to take past history into account, leading to delayed diagnosis. Patients also highlighted the need for improved reporting of results and a solution to the “inconclusive” diagnostic status.

These findings will be used to advise the ERS Task Force guidelines for diagnosing PCD, and should help stakeholders responsible for improving existing services and expanding provision for diagnosis of this rare disease.

The international PCD patients’ diagnostic experience calls for earlier referral and access to specialist serviceshttp://ow.ly/lxsR300T8kO

PICADAR: a diagnostic predictive tool for primary ciliary dyskinesia

Symptoms of primary ciliary dyskinesia (PCD) are nonspecific and guidance on whom to refer for testing is limited. Diagnostic tests for PCD are highly specialised, requiring expensive equipment and experienced PCD scientists. This study aims to develop a practical clinical diagnostic tool to identify patients requiring testing.

Patients consecutively referred for testing were studied. Information readily obtained from patient history was correlated with diagnostic outcome. Using logistic regression, the predictive performance of the best model was tested by receiver operating characteristic curve analyses. The model was simplified into a practical tool (PICADAR) and externally validated in a second diagnostic centre.

Of 641 referrals with a definitive diagnostic outcome, 75 (12%) were positive. PICADAR applies to patients with persistent wet cough and has seven predictive parameters: full-term gestation, neonatal chest symptoms, neonatal intensive care admittance, chronic rhinitis, ear symptoms, situs inversus and congenital cardiac defect. Sensitivity and specificity of the tool were 0.90 and 0.75 for a cut-off score of 5 points. Area under the curve for the internally and externally validated tool was 0.91 and 0.87, respectively.

PICADAR represents a simple diagnostic clinical prediction rule with good accuracy and validity, ready for testing in respiratory centres referring to PCD centres.

PICADAR is a simple diagnostic prediction tool for PCD with good accuracy and validity that is now ready for testinghttp://ow.ly/X6y9s

[Primary ciliary dyskinesia]

Primary ciliary dyskinesia (PCD) is a rare disease, but causes symptoms that resemble far more common respiratory diseases. Late diagnosis is common, when damage to the respiratory system has already occurred. This article aims to elucidate the condition and the diagnostic methods available. The article is based on literature searches in PubMed and the author's own experience of patient treatment and clinical research.

Epidemiology of chronic rhinosinusitis, selected risk factors, comorbidities, and economic burden

Chronic rhinosinusitis (CRS) is a relevant and prevalent medical condition in Germany, Europe and the world. If analysed in detail, the prevalence of CRS shows regional and temporary variety. In this review, currently available data regarding the prevalence of CRS is therefore sorted by country and/or region, time point of data collection and the CRS-definition employed. Risk factors like smoking and gastroesophageal reflux are discussed regarding their influence on CRS prevalence. Moreover, comorbidities of CRS, like asthma, conditions of the cardiovascular system and depression are listed and their influence on CRS is discussed. Furthermore, data on CRS prevalence in special cohorts, like immunocompromised patients, are presented. To estimate the economic burden of CRS, current data e.g. from Germany and the USA are included in this review.

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.

Combination testing in PCD diagnosis remains the most accurate approach, but standardisation is neededhttp://ow.ly/TLEDu

Chronic obstructive pulmonary diseases in children

OBJECTIVES

To verify and describe the main events related to the diagnosis and management of chronic obstructive pulmonary diseases in children (COPDC) and adolescents, considering the interrelated physiopathology, genetic, and environmental characteristics.

SOURCES

Relevant literature from PubMed was selected and reviewed.

SUMMARY OF THE FINDINGS

COPDC have an environmental and/or genetic origin and its manifestation has manifold genotypes, phenotypes, and endotypes. Although COPDC has no cure, it can be clinically controlled. Chronic cough is the main symptom and bronchiectasis can be present in several COPDC patients. The management of COPDC is more effective if based on guidelines and when treatment regimen adherence is promoted. Oral and inhaled corticosteroids, bronchodilators, inhaled antibiotics, and treatment of pulmonary exacerbation (PE) are the bases of COPDC management, and should be individualized for each patient.

CONCLUSIONS

Correct diagnosis and knowledge of risk factors and comorbidities are essential in COPDC management. Procedures and drugs used should be based on specific guidelines for each COPDC case. Treatment adherence is critical to obtain the benefits of management. COPDC clinical control must be evaluated by the decrease in PEs, improved quality of life, reduction of pulmonary function loss, and lung structural damage. For most cases of COPDC, monitoring by interdisciplinary teams in specialized reference centers with surveillance strategies and continuous care leads to better outcomes, which must be evaluated by decreasing pulmonary function damage and deterioration, better prognosis, better quality life, and increased life expectancy.

Racial disparities in heterotaxy syndrome

BACKGROUND

Heterotaxy syndrome (HTX) is a constellation of defects including abnormal organ lateralization and often including congenital heart defects. HTX has widely divergent population-based estimates of prevalence, racial and ethnic predominance, and mortality in current literature.

METHODS

The objective of this study was to use a population-based registry to investigate potential racial and ethnic disparities in HTX. Using the Texas Birth Defects Registry, we described clinical features and mortality of HTX among infants delivered from 1999 to 2006. We calculated birth prevalence and crude prevalence (cPR) ratios for infant sex, maternal diabetes, and sociodemographic factors.

RESULTS

A total of 353 HTX cases were identified from 2,993,604 births (prevalence ratio = 1.18 per 10,000 live births. HTX prevalence was approximately 70% higher among infants of Hispanic and non-Hispanic black mothers and 28% higher among female infants (cPR = 1.28; 95% confidence interval,1.04-1.59). There was a twofold higher female preponderance for infants of mothers who were non-Hispanic white or black. Mothers with diabetes were three times more likely to have a child with HTX compared with nondiabetics (cPR = 3.13; 95% confidence interval, 2.12-4.45). Among nondiabetics, HTX cases were 86% more likely to have a Hispanic mother and 72% a non-Hispanic black mother. First-year mortality for live born children with HTX was 30.9%.

CONCLUSION

This study represents one of the largest population-based studies of HTX to date, with a novel finding of higher rates of HTX among Hispanic infants of mostly Mexican origin, as well as among female infants of only non-Hispanic white and black mothers. These findings warrant further investigation.

Teratozoospermia: spotlight on the main genetic actors in the human

BACKGROUND

Male infertility affects >20 million men worldwide and represents a major health concern. Although multifactorial, male infertility has a strong genetic basis which has so far not been extensively studied. Recent studies of consanguineous families and of small cohorts of phenotypically homogeneous patients have however allowed the identification of a number of autosomal recessive causes of teratozoospermia. Homozygous mutations of aurora kinase C (AURKC) were first described to be responsible for most cases of macrozoospermia. Other genes defects have later been identified in spermatogenesis associated 16 (SPATA16) and dpy-19-like 2 (DPY19L2) in patients with globozoospermia and more recently in dynein, axonemal, heavy chain 1 (DNAH1) in a heterogeneous group of patients presenting with flagellar abnormalities previously described as dysplasia of the fibrous sheath or short/stump tail syndromes, which we propose to call multiple morphological abnormalities of the flagella (MMAF).

METHODS

A comprehensive review of the scientific literature available in PubMed/Medline was conducted for studies on human genetics, experimental models and physiopathology related to teratozoospermia in particular globozoospermia, large headed spermatozoa and flagellar abnormalities. The search included all articles with an English abstract available online before September 2014.

RESULTS

Molecular studies of numerous unrelated patients with globozoospermia and large-headed spermatozoa confirmed that mutations in DPY19L2 and AURKC are mainly responsible for their respective pathological phenotype. In globozoospermia, the deletion of the totality of the DPY19L2 gene represents ∼ 81% of the pathological alleles but point mutations affecting the protein function have also been described. In macrozoospermia only two recurrent mutations were identified in AURKC, accounting for almost all the pathological alleles, raising the possibility of a putative positive selection of heterozygous individuals. The recent identification of DNAH1 mutations in a proportion of patients with MMAF is promising but emphasizes that this phenotype is genetically heterogeneous. Moreover, the identification of mutations in a dynein strengthens the emerging point of view that MMAF may be a phenotypic variation of the classical forms of primary ciliary dyskinesia. Based on data from human and animal models, the MMAF phenotype seems to be favored by defects directly or indirectly affecting the central pair of axonemal microtubules of the sperm flagella.

CONCLUSIONS

The studies described here provide valuable information regarding the genetic and molecular defects causing infertility, to improve our understanding of the physiopathology of teratozoospermia while giving a detailed characterization of specific features of spermatogenesis. Furthermore, these findings have a significant influence on the diagnostic strategy for teratozoospermic patients allowing the clinician to provide the patient with informed genetic counseling, to adopt the best course of treatment and to develop personalized medicine directly targeting the defective gene products.

Diagnosis and management of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disorder with defective structure and/or function of motile cilia/flagella, causing chronic upper and lower respiratory tract infections, fertility problems, and disorders of organ laterality. Diagnosing PCD requires a combined approach utilizing characteristic phenotypes and complementary methods for detection of defects of ciliary function and ultrastructure, measurement of nasal nitric oxide and genetic testing. Currently, biallelic mutations in 31 different genes have been linked to PCD allowing a genetic diagnosis in approximately ~ 60% of cases. Management includes surveillance of pulmonary function, imaging, and microbiology of upper and lower airways in addition to daily airway clearance and prompt antibiotic treatment of infections. Early referral to specialized centers that use a multidisciplinary approach is likely to improve outcomes. Currently, evidence-based knowledge on PCD care is missing let alone management guidelines. Research and clinical investigators, supported by European and North American patient support groups, have joined forces under the name of BESTCILIA, a European Commission funded consortium dedicated to improve PCD care and knowledge. Core programs of this network include the establishment of an international PCD registry, the generation of disease specific PCD quality of life questionnaires, and the first randomized controlled trial in PCD.

Diagnosis and management of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disorder with defective structure and/or function of motile cilia/flagella, causing chronic upper and lower respiratory tract infections, fertility problems, and disorders of organ laterality. Diagnosing PCD requires a combined approach utilizing characteristic phenotypes and complementary methods for detection of defects of ciliary function and ultrastructure, measurement of nasal nitric oxide and genetic testing. Currently, biallelic mutations in 31 different genes have been linked to PCD allowing a genetic diagnosis in approximately ~ 60% of cases. Management includes surveillance of pulmonary function, imaging, and microbiology of upper and lower airways in addition to daily airway clearance and prompt antibiotic treatment of infections. Early referral to specialized centers that use a multidisciplinary approach is likely to improve outcomes. Currently, evidence-based knowledge on PCD care is missing let alone management guidelines. Research and clinical investigators, supported by European and North American patient support groups, have joined forces under the name of BESTCILIA, a European Commission funded consortium dedicated to improve PCD care and knowledge. Core programs of this network include the establishment of an international PCD registry, the generation of disease specific PCD quality of life questionnaires, and the first randomized controlled trial in PCD.

Diagnosis and management of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an inherited autosomal-recessive disorder of motile cilia characterised by chronic lung disease, rhinosinusitis, hearing impairment and subfertility. Nasal symptoms and respiratory distress usually start soon after birth, and by adulthood bronchiectasis is invariable. Organ laterality defects, usually situs inversus, occur in ∼50% of cases. The estimated prevalence of PCD is up to ∼1 per 10,000 births, but it is more common in populations where consanguinity is common. This review examines who to refer for diagnostic testing. It describes the limitations surrounding diagnosis using currently available techniques and considers whether recent advances to genotype patients with PCD will lead to genetic testing and screening to aid diagnosis in the near future. It discusses the challenges of monitoring and treating respiratory and ENT disease in children with PCD.

Overcoming challenges in the management of primary ciliary dyskinesia: the UK model

Primary ciliary dyskinesia (PCD) is an autosomal recessive disease associated with bronchiectasis, chronic rhinosinusitis, infertility and situs inversus. Estimates of prevalence vary widely, but is probably between 1:10,000- 1:40,000 in most populations. A number of observational studies indicate that access to services to diagnose and manage patients with PCD vary both between and within countries. Diagnosis is often delayed and frequently missed completely. The prognosis of patients with PCD is variable, but evidence suggests that it is improved by early diagnosis and specialist care. This article briefly reviews the literature concerning PCD and the evidence that specialist care will improve healthcare outcomes. The article specifically refers to a new national service in the UK.

Genetic Testing in the Diagnosis of Primary Ciliary Dyskinesia: State-of-the-Art and Future Perspectives

Primary ciliary dyskinesia (PCD) is a heterogeneous autosomal recessive condition affecting around 1:15,000. In people with PCD, microscopic motile cilia do not move normally resulting in impaired clearance of mucus and debris leading to repeated sinopulmonary infection. If diagnosis is delayed, permanent bronchiectasis and deterioration of lung function occurs. Other complications associated with PCD include congenital heart disease, hearing impairment and infertility. A small number of longitudinal studies suggest that lung function deteriorates before diagnosis of PCD but may stabilise following diagnosis with subsequent specialist management. Early diagnosis is therefore essential, but for a number of reasons referral for diagnostic testing is often delayed until older childhood or even adulthood. Functional diagnostic tests for PCD are expensive, time consuming and require specialist equipment and scientists. In the last few years, there have been considerable developments to identify genes associated with PCD, currently enabling 65% of patients to be identified by bi-allelic mutations. The rapid identification of new genes continues. This review will consider the evidence that early diagnosis of PCD is beneficial. It will review the recent advances in identification of PCD-associated genes and will discuss the role of genetic testing in PCD. It will then consider whether screening for PCD antenatally or in the new born is likely to become a feasible and acceptable for this rare disease.

Culture of primary ciliary dyskinesia epithelial cells at air-liquid interface can alter ciliary phenotype but remains a robust and informative diagnostic aid

Background

The diagnosis of primary ciliary dyskinesia (PCD) requires the analysis of ciliary function and ultrastructure. Diagnosis can be complicated by secondary effects on cilia such as damage during sampling, local inflammation or recent infection. To differentiate primary from secondary abnormalities, re-analysis of cilia following culture and re-differentiation of epithelial cells at an air-liquid interface (ALI) aids the diagnosis of PCD. However changes in ciliary beat pattern of cilia following epithelial cell culture has previously been described, which has brought the robustness of this method into question. This is the first systematic study to evaluate ALI culture as an aid to diagnosis of PCD in the light of these concerns.

Methods

We retrospectively studied changes associated with ALI-culture in 158 subjects referred for diagnostic testing at two PCD centres. Ciliated nasal epithelium (PCD n = 54; non-PCD n = 111) was analysed by high-speed digital video microscopy and transmission electron microscopy before and after culture.

Results

Ciliary function was abnormal before and after culture in all subjects with PCD; 21 PCD subjects had a combination of static and uncoordinated twitching cilia, which became completely static following culture, a further 9 demonstrated a decreased ciliary beat frequency after culture. In subjects without PCD, secondary ciliary dyskinesia was reduced.

Conclusions

The change to ciliary phenotype in PCD samples following cell culture does not affect the diagnosis, and in certain cases can assist the ability to identify PCD cilia.

Ciliated cultures from patients with primary ciliary dyskinesia do not produce nitric oxide or inducible nitric oxide synthase during early infection

BACKGROUND

The mechanism behind why patients with primary ciliary dyskinesia (PCD) exhibit low nasal and exhaled nitric oxide (NO) remains unknown. One hypothesis is that reduced NO biosynthesis is caused by a defect in one or more NO synthases (NOSs). In healthy cells, the biosynthesis of NO is increased following exposure to respiratory pathogens. Here, we aimed to investigate whether ciliated epithelial cells from patients with PCD increase NO production following pneumococcal infection.

METHODS

Human respiratory epithelium was cultured to a basal or ciliated cell phenotype using submerged or air-liquid interface cultures, respectively. Cells were exposed to media or pneumococci until cells became damaged (< 4 h). Apical fluids were collected prior and following infection, and NO production was determined using chemiluminescence. NOS gene expression was determined using real-time quantitative polymerase chain reaction.

RESULTS

Levels of NO and NOS2 gene expression increased significantly following infection of healthy ciliated epithelial cells but not basal cells. No increase in NO was seen in ciliated cell cultures from patients with PCD, and NOS2 gene expression remained unchanged from baseline.

CONCLUSIONS

These results suggest that the biosynthesis of NO in ciliated cells from patients with PCD is abnormal following early bacterial challenge, suggesting an abnormality in the function of inducible NOS in PCD.

Growing up with Primary Ciliary Dyskinesia in Bradford, UK: exploring patients experiences as a physiotherapist

Primary Ciliary Dyskinesia (PCD) is a condition which causes impaired mucociliary clearance, resulting in sputum retention and recurrent respiratory tract infections. Physiotherapy, in the form of airway clearance techniques and exercise is recommended to patients with PCD to facilitate sputum clearance. As children diagnosed with PCD develop into adults, understanding their experiences of growing up with this long-term condition and undertaking physiotherapy may help to provide insight to clinicians. No previous research has been published which explores the lived experiences of children and young people with PCD. The prevalence of PCD in Bradford in the North of the UK is unusually high, signifying the importance of understanding the experiences of this patient population. This qualitative study used Interpretive Phenomenological Analysis to allow the researcher, as a physiotherapist, to investigate the lived experiences of five paediatric patients with PCD. While patients' experiences are all unique, three themes emerged across the analysis of the interviews: (1) the experiences of day to day life with the symptoms and treatment burden of PCD; (2) participants' awareness of their own symptoms and knowledge of PCD; and (3) the development of mastery skills and devolution of management from the family to the growing child. The results from this study suggested that facilitation of disease acceptance, strategies to increase patient empowerment, the use of patient-centred communication and understanding the contextualisation of patients' experiences may all help to guide clinical practice.

Primary ciliary dyskinesia. Recent advances in diagnostics, genetics, and characterization of clinical disease

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous recessive disorder of motile cilia that leads to oto-sino-pulmonary diseases and organ laterality defects in approximately 50% of cases. The estimated incidence of PCD is approximately 1 per 15,000 births, but the prevalence of PCD is difficult to determine, primarily because of limitations in diagnostic methods that focus on testing ciliary ultrastructure and function. Diagnostic capabilities have recently benefitted from (1) documentation of low nasal nitric oxide production in PCD and (2) discovery of biallelic mutations in multiple PCD-causing genes. The use of these complementary diagnostic approaches shows that at least 30% of patients with PCD have normal ciliary ultrastructure. More accurate identification of patients with PCD has also allowed definition of a strong clinical phenotype, which includes neonatal respiratory distress in >80% of cases, daily nasal congestion and wet cough starting soon after birth, and early development of recurrent/chronic middle-ear and sinus disease. Recent studies, using advanced imaging and pulmonary physiologic assessments, clearly demonstrate early onset of lung disease in PCD, with abnormal air flow mechanics by age 6-8 years that is similar to cystic fibrosis, and age-dependent onset of bronchiectasis. The treatment of PCD is not standardized, and there are no validated PCD-specific therapies. Most patients with PCD receive suboptimal management, which should include airway clearance, regular surveillance of pulmonary function and respiratory microbiology, and use of antibiotics targeted to pathogens. The PCD Foundation is developing a network of clinical centers, which should improve diagnosis and management of PCD.

Primary ciliary dyskinesia. Recent advances in diagnostics, genetics, and characterization of clinical disease

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous recessive disorder of motile cilia that leads to oto-sino-pulmonary diseases and organ laterality defects in approximately 50% of cases. The estimated incidence of PCD is approximately 1 per 15,000 births, but the prevalence of PCD is difficult to determine, primarily because of limitations in diagnostic methods that focus on testing ciliary ultrastructure and function. Diagnostic capabilities have recently benefitted from (1) documentation of low nasal nitric oxide production in PCD and (2) discovery of biallelic mutations in multiple PCD-causing genes. The use of these complementary diagnostic approaches shows that at least 30% of patients with PCD have normal ciliary ultrastructure. More accurate identification of patients with PCD has also allowed definition of a strong clinical phenotype, which includes neonatal respiratory distress in >80% of cases, daily nasal congestion and wet cough starting soon after birth, and early development of recurrent/chronic middle-ear and sinus disease. Recent studies, using advanced imaging and pulmonary physiologic assessments, clearly demonstrate early onset of lung disease in PCD, with abnormal air flow mechanics by age 6-8 years that is similar to cystic fibrosis, and age-dependent onset of bronchiectasis. The treatment of PCD is not standardized, and there are no validated PCD-specific therapies. Most patients with PCD receive suboptimal management, which should include airway clearance, regular surveillance of pulmonary function and respiratory microbiology, and use of antibiotics targeted to pathogens. The PCD Foundation is developing a network of clinical centers, which should improve diagnosis and management of PCD.

A dextrocardia in a foetal Egyptian mummy?

Egyptian foetal mummies are rare archaeological artefacts. We report the case of a mummified foetus with a highly probable dextrocardia accurately depicted by computed tomography scan.

Splice-site mutations in the axonemal outer dynein arm docking complex gene CCDC114 cause primary ciliary dyskinesia

Defects in motile cilia and sperm flagella cause primary ciliary dyskinesia (PCD), characterized by chronic airway disease, infertility, and left-right laterality disturbances, usually as a result of loss of the outer dynein arms (ODAs) that power cilia/flagella beating. Here, we identify loss-of-function mutations in CCDC114 causing PCD with laterality malformations involving complex heart defects. CCDC114 is homologous to DCC2, an ODA microtubule-docking complex component of the biflagellate alga Chlamydomonas. We show that CCDC114 localizes along the entire length of human cilia and that its deficiency causes a complete absence of ciliary ODAs, resulting in immotile cilia. Thus, CCDC114 is an essential ciliary protein required for microtubular attachment of ODAs in the axoneme. Fertility is apparently not greatly affected by CCDC114 deficiency, and qPCR shows that this may explained by low transcript expression in testis compared to ciliated respiratory epithelium. One CCDC114 mutation, c.742G>A, dating back to at least the 1400s, presents an important diagnostic and therapeutic target in the isolated Dutch Volendam population.

Effectiveness of sequencing selected exons of DNAH5 and DNAI1 in diagnosis of primary ciliary dyskinesia

INTRODUCTION

Primary ciliary dyskinesia (PCD) is a rare genetically heterogenous condition. Mutations in DNAH5 or DNAI1 genes can be found in about a third of the patients with PCD. Increased occurrence of mutations was described in several exons of these long genes. The objective of the study was to test the sensitivity of sequencing of selected 13 exons (as compared to costly sequencing of all 100 exons of the two genes), and to determine the prevalence of the DNAH5 or DNAI1 mutations in the Czech PCD database.

METHODS

The Czech national PCD database has identified 31 pediatric patients, diagnosed based on clinical findings and tests on the ciliated epithelium. Twenty-seven patients from 24 families agreed on genetic testing. In the first step, direct sequencing of selected 13 exons (9 of DNAH5 and 4 of DNAI1) was performed, and then we compared its effectiveness in detecting at least one mutation with results of sequencing all 100 exons of the two genes.

RESULTS

The sequencing of all exons identified compound heterozygosity for PCD mutations in nine patients from eight families (DNAH5 in eight and DNAI1 in one patient), and heterozygozity for a DNAH5 mutation of uncertain functional significance in one additional patient. The first step of selected exon sequencing detected a mutation in five out of these eight families, its actual sensitivity being 62.5%, with a high predictive value. The phenotypic and clinical characteristics of all the paediatric patients with PCD are shown.

CONCLUSIONS

Selected exon sequencing detects at least one mutated allele in over a half of our patients who have PCD due to DNAH5 or DNAI1 mutations. To lower the costs of the genetic testing, targeted step-wise genetic testing may be a reasonable approach to detect mutations in PCD patients, especially if their phenotype is taken into account.

CCDC103 mutations cause primary ciliary dyskinesia by disrupting assembly of ciliary dynein arms

Cilia are essential for fertilization, respiratory clearance, cerebrospinal fluid circulation and establishing laterality. Cilia motility defects cause primary ciliary dyskinesia (PCD, MIM244400), a disorder affecting 1:15,000-30,000 births. Cilia motility requires the assembly of multisubunit dynein arms that drive ciliary bending. Despite progress in understanding the genetic basis of PCD, mutations remain to be identified for several PCD-linked loci. Here we show that the zebrafish cilia paralysis mutant schmalhans (smh(tn222)) encodes the coiled-coil domain containing 103 protein (Ccdc103), a foxj1a-regulated gene product. Screening 146 unrelated PCD families identified individuals in six families with reduced outer dynein arms who carried mutations in CCDC103. Dynein arm assembly in smh mutant zebrafish was rescued by wild-type but not mutant human CCDC103. Chlamydomonas Ccdc103/Pr46b functions as a tightly bound, axoneme-associated protein. These results identify Ccdc103 as a dynein arm attachment factor that causes primary ciliary dyskinesia when mutated.

The emerging genetics of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an autosomal recessive, rare, genetically heterogeneous condition characterized by oto-sino-pulmonary disease together with situs abnormalities (Kartagener syndrome) owing to abnormal ciliary structure and function. Most patients are currently diagnosed with PCD based on the presence of defective ciliary ultrastructure. However, diagnosis often remains challenging due to variability in the clinical phenotype and ciliary ultrastructural changes. Some patients with PCD have normal ciliary ultrastructure, which further confounds the diagnosis. A genetic test for PCD exists but is of limited value because it investigates only a limited number of mutations in only two genes. The genetics of PCD is complicated owing to the complexity of axonemal structure that is highly conserved through evolution, which is comprised of multiple proteins. Identifying a PCD-causing gene is challenging due to locus and allelic heterogeneity. Despite genetic heterogeneity, multiple tools have been used, and there are 11 known PCD-causing genes. All of these genes combined explain approximately 50% of PCD cases; hence, more genes need to be identified. This review briefly describes the current knowledge regarding the genetics of PCD and focuses on the methodologies used to identify novel PCD-causing genes, including a candidate gene approach using model organisms, next-generation massively parallel sequencing techniques, and the use of genetically isolated populations. In conclusion, we demonstrate the multipronged approach that is necessary to circumvent challenges due to genetic heterogeneity to uncover genetic causes of PCD.

Primary ciliary dyskinesia: evaluation using cilia beat frequency assessment via spectral analysis of digital microscopy images

Ciliary beat frequency (CBF) measurements provide valuable information for diagnosing of primary ciliary dyskinesia (PCD). We developed a system for measuring CBF, used it in association with electron microscopy to diagnose PCD, and then analyzed characteristics of PCD patients. The CBF measurement system was based on power spectra measured through digital imaging. Twenty-four patients suspected of having PCD (age 1-19 yr) were selected from a group of 75 children and adolescents with pneumopathies of unknown causes. Ten healthy, nonsmoking volunteers (age ≥ 17 yr) served as a control group. Nasal brush samples were collected, and CBF and electron microscopy were performed. PCD was diagnosed in 12 patients: 5 had radial spoke defects, 3 showed absent central microtubule pairs with transposition, 2 had outer dynein arm defects, 1 had a shortened outer dynein arm, and 1 had a normal ultrastructure. Previous studies have reported that the most common cilia defects are in the dynein arm. As expected, the mean CBF was higher in the control group (P < 0.001) and patients with normal ultrastructure (P < 0.002), than in those diagnosed with cilia ultrastructural defects (i.e., PCD patients). An obstructive ventilatory pattern was observed in 70% of the PCD patients who underwent pulmonary function tests. All PCD patients presented bronchial wall thickening on chest computed tomography scans. The protocol and diagnostic techniques employed allowed us to diagnose PCD in 16% of patients in this study.

A sperm viability test using SYBR-14/propidium iodide flow cytometry as a tool for rapid screening of primary ciliary dyskinesia patients and for choosing sperm sources for intracytoplasmic sperm injection

Spermatozoa viability tests based on dual-color flow cytometry after staining with Sybr-14/propidium iodide were performed on 44 men with complete asthenospermia for primary ciliary dyskinesia (PCD) screening, and seven were identified with PCD by electron microscopy of ultrastructural ciliary defects. Six PCD patients underwent eight intracytoplasmic sperm injection therapy cycles using ejaculated sperm or testicular sperm, obtaining a mean fertilization rate of 46.6%, with three healthy babies born and one in utero at the time of writing.

Tubulin tyrosine ligase-like 1 deficiency results in chronic rhinosinusitis and abnormal development of spermatid flagella in mice

Tubulin tyrosine ligase-like 1 (TTLL1) protein is a member of the tubulin tyrosine ligase superfamily of proteins that are involved in the posttranslational polyglutamylation of tubulin in axonemal microtubules within cilia and flagella. To investigate the physiological role of TTLL1, the authors generated mice with a gene trap mutation in the Ttll1 gene that provide confirmation in a mammalian model that polyglutamylation plays an important role in some ciliary and flagellar functions. For the first time, mice homozygous for the Ttll1 mutation exhibited accumulations of exudates in the nasal passages and sinuses, rhinosinusitis, otitis media, and male infertility. In homozygous mutant male mice, abnormal sperm morphology and function were characterized by shortened or absent flagella and immotility. Although homozygous mutant males were infertile, the females were fertile. These findings are consistent with a diagnosis of primary ciliary dyskinesia (PCD) resulting from ciliary dysfunction. They indicate that Ttll1 is essential for normal motility of respiratory cilia and the biogenesis and function of sperm flagella but that the defect does not result in the hydrocephalus or laterality defects often seen in other forms of PCD. The absence of early-onset lethal hydrocephalus in Ttll1-mutant mice may enable studies to evaluate the long-term effects of PCD in the respiratory system of mice. Although no mutations in the orthologous gene have been linked with PCD in humans, investigating the role of TTLL1 and polyglutamylation of tubulin in cilia and flagella should advance an understanding of the biogenesis and function of these organelles in mammals and have potential diagnostic and therapeutic applications.