Primary ciliary dyskinesia: diagnostic and phenotypic features

Familial risk of chronic rhinosinusitis with and without nasal polyposis: genetics or environment

BACKGROUND

Chronic rhinosinusitis (CRS) is a highly prevalent inflammatory condition, with significant effects on morbidity and quality of life, yet little is known about its pathogenesis. Preliminary evidence suggests there is a heritable component to the multifactorial etiology of CRS; however, our understanding of this genetic susceptibility is limited.

METHODS

Using an extensive genealogical database linked to medical records, the risk of CRS with nasal polyps (CRSwNP) and without polyps (CRSsNP) was calculated for relatives and spouses of adult probands (1638 CRSwNP and 24,200 CRSsNP patients diagnosed between 1996 and 2011) and were compared to random population controls matched 5:1 on sex and birth year from Cox regression models.

RESULTS

First-degree relatives (1stDRs) of CRSwNP patients demonstrated a 4.1-fold increased risk (p < 10(-3) ) of carrying the same diagnosis, whereas second-degree relatives (2ndDRs) demonstrated a 3.3-fold increased risk (p < 0.004), compared to controls. In CRSsNP patients, 1stDRs were at 2.4-fold increased risk (p < 10(-15) ), whereas 2ndDRs were at 1.4-fold increased risk (p < 10(-15) ) of the same diagnosis. Third-degree relatives (3rdDRs) had a slight increased risk at 1.1-fold (p < 10(-7) ). Spouses of CRSsNP patients, who likely share environmental circumstances, exhibited a 2-fold increased risk (p < 10(-15) ). No increased risk was observed in spouses of CRSwNP patients.

CONCLUSION

In the largest population study to date, a significant familial risk is confirmed in CRSwNP and CRSsNP, which may have a shared genetic and environmental component. Further understanding of the genetic basis of CRS and its interplay with environment factors could clarify disease etiology and lead to more effective targeted treatments.

Clinical features of primary ciliary dyskinesia in Cyprus with emphasis on lobectomized patients

BACKGROUND

Despite the manifestations of primary ciliary dyskinesia (PCD) in early life, the diagnosis is often much delayed. Since 1998 in Cyprus, we have established the only national diagnostic and clinical referral center for PCD.

OBJECTIVE

To review the phenotypic features at presentation of PCD patients in Cyprus in relation to age at diagnosis, with emphasis on previously lobectomised patients.

METHODS

The medical records of the diagnosed PCD patients were retrospectively reviewed to obtain clinical data on presentation.

RESULTS

Thirty patients, aged 13.9 years (range 0.1, 58.4 years), were diagnosed with PCD. Twelve of them presented after the age of 18. The most common manifestations were chronic cough (100%), chronic rhinorrhea (96.7%), sputum production (92.9%), laterality defects (63.3%), a history of pneumonia (53.3%) and neonatal respiratory distress (50%). A history of lobectomy in the past was recorded in 16.7% (5 patients). Patients who presented in adulthood had significantly higher frequency of lobectomy (41.7% vs 0%, p-value = 0.006) and had more frequently low FEV1 (58.3% vs 0%, p-value = 0.015) than those who presented before. Serial measurements of FEV1 and FVC indicated significantly lower intercepts in lobectomised compared to the adult non-lobectomised patients both in terms of FEV1 (-4.90 vs -1.80, p-value = 0.022) and FVC (-5.43 vs -1.91, p-value = 0.029) z-score levels. Change in FEV1 and FVC across time was not statistically significant in either group.

CONCLUSIONS

PCD often remains undiagnosed up to adulthood accompanied by appearance of advanced lung disease. Performance of lobectomies seems to be a poor prognostic factor for PCD in adulthood.

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.

Simultaneous sinus and lung infections in patients with primary ciliary dyskinesia

CONCLUSION

The sinuses should be considered as a bacterial reservoir and a target for surgery and antibiotic treatment in patients with primary ciliary dyskinesia (PCD). The observed decrease in serum precipitating antibodies (precipitins) against Pseudomonas aeruginosa may indicate a beneficial effect of combined endoscopic sinus surgery (ESS) and concomitant medical treatment.

OBJECTIVES

The purpose of this research, which is the first study addressing bacteriology in the sinuses of patients with PCD, was to examine the association between sinus and lung infections.

METHODS

We reviewed findings of bacterial pathogens from the sinuses obtained during ESS and the lung infection status in eight PCD patients over a 6 year period. Precipitins against P. aeruginosa were used as a marker of severity of chronic infection and effect of treatment.

RESULTS

Preoperatively, seven of the eight patients (88%) exhibited intermittent or chronic pulmonary infection with P. aeruginosa. Sinus cultures were obtained during ESS in seven patients. The sinuses were colonized with P. aeruginosa in four of seven patients (57%). Bacterial sinusitis was found in five of seven patients (71%) and the same bacterium was found in the sinuses and lungs in all cases. Decreasing precipitins against P. aeruginosa were observed postoperatively in three of four evaluable patients.

The role of molecular genetic analysis in the diagnosis of primary ciliary dyskinesia

RATIONALE

Primary ciliary dyskinesia (PCD) is an autosomal recessive genetic disorder of motile cilia. The diagnosis of PCD has previously relied on ciliary analysis with transmission electron microscopy or video microscopy. However, patients with PCD may have normal ultrastructural appearance, and ciliary analysis has limited accessibility. Alternatively, PCD can be diagnosed by demonstrating biallelic mutations in known PCD genes. Genetic testing is emerging as a diagnostic tool to complement ciliary analysis where interpretation and access may delay diagnosis.

OBJECTIVES

To determine the diagnostic yield of genetic testing of patients with a confirmed or suspected diagnosis of PCD in a multiethnic urban center.

METHODS

Twenty-eight individuals with confirmed PCD on transmission electron microscopy of ciliary ultrastructure and 24 individuals with a probable diagnosis of PCD based on a classical PCD phenotype and low nasal nitric oxide had molecular analysis of 12 genes associated with PCD.

RESULTS

Of 49 subjects who underwent ciliary biopsy, 28 (57%) were diagnosed with PCD through an ultrastructural defect. Of the 52 individuals who underwent molecular genetic analysis, 22 (42%) individuals had two mutations in known PCD genes. Twenty-four previously unreported mutations in known PCD genes were observed. Combining both diagnostic modalities of biopsy and molecular genetics, the diagnostic yield increased to 69% compared with 57% based on biopsy alone.

CONCLUSIONS

The diagnosis of PCD is challenging and has traditionally relied on ciliary biopsy, which is unreliable as the sole criterion for a definitive diagnosis. Molecular genetic analysis can be used as a complementary test to increase the diagnostic yield.

Multicenter analysis of body mass index, lung function, and sputum microbiology in primary ciliary dyskinesia

BACKGROUND

No studies longitudinally, simultaneously assessed body mass index (BMI) and spirometry in primary ciliary dyskinesia (PCD).

METHODS

We determined BMI and spirometry in 158 PCD children and adolescents from London, UK (n = 75), Naples, Italy (n = 23) and Copenhagen, Denmark (n = 60) at first presentation and during follow-up. Annual BMI and spirometry were prospectively collected and analyzed over blocks of 2, 4, and 6 consecutive years. Sputum pathogens were recorded.

RESULTS

Age at first spirometry was 8.7 years (range, 4.2-17.4). Mean Z scores of first measured BMI, FEV1, FVC, and FEF(25-75) were 0.01, -1.37, -0.84, and -1.68, respectively. First spirometry was not more frequently impaired in patients referred at age ≥6 years than in those referred at preschool age (P = 0.13). There were no differences in slopes for BMI, FEV1, FVC, or FEF(25-75) over any time block. H. influenzae was the most common pathogen, isolated at least once in 65% of patients. P. aeruginosa was found in 58 subjects (37%) of whom 8 (5%) were chronically infected. Neither pathogens was associated with spirometry changes.

CONCLUSIONS

Preschool referral to a PCD center was not associated with better spirometry or BMI. PCD children and adolescents receiving centralized care show steady BMI and spirometry during medium term follow-up. There was a high prevalence of Pseudomonas aeruginosa infection, but the evolution of spirometry or BMI was not affected by this microorganism in medium term. Despite our longitudinal analysis showed no differences between the three centers, the assessment of spirometry and BMI over time represents a quality improvement tool. Future studies are needed to highlight the role of spirometry and BMI in long term PCD management and identify subgroups of patients with a higher risk of early lung failure or nutritional problems.

Primary ciliary dyskinesia: overlooked and undertreated in children

Primary ciliary dyskinesia (PCD) is a multi-organ disorder associated with chronic oto-sino-pulmonary disease, neonatal respiratory distress, situs abnormalities and reduced fertility. Repeated respiratory tract infections leads to the almost universal development of bronchiectasis. These clinical manifestations are a consequence of poorly functioning motile cilia. However, confirming the diagnosis is quite difficult and is often delayed, so the true incidence of PCD may be significantly higher than current estimates. Nasal nitric oxide has been earmarked as a useful screening tool for identifying patients, but its use is limited in pre-school-aged children. Due to the rarity of PCD, the evidence base for management is somewhat limited, and treatment regimens are extrapolated from other suppurative lung disorders, like cystic fibrosis.

Primary ciliary dyskinesia and neonatal respiratory distress

BACKGROUND AND OBJECTIVE

Primary ciliary dyskinesia (PCD) is a rare inherited disease affecting motile cilia lining the respiratory tract. Despite neonatal respiratory distress as an early feature, diagnosis is typically delayed until late childhood. Our objective was to identify characteristics that differentiate PCD from common causes of term neonatal respiratory distress.

METHODS

This was a case-control study. Patients with PCD born after 1994 attending a regional PCD clinic who had a history of neonatal respiratory distress (n = 46) were included. Controls (n = 46), term neonates with respiratory distress requiring a chest radiograph, were randomly selected from hospital birth records and matched on gender, birth month/year, and mode of delivery. Multiple logistic regression was used to determine the association between neonatal characteristics and PCD diagnosis. The diagnostic performance of the best predictive variables was estimated by calculating sensitivity and specificity.

RESULTS

PCD cases required more oxygen therapy (39 cases, 29 controls, P = .01), longer duration of oxygen therapy (PCD mean = 15.2 days, control mean = 0.80 days, P < .01), had later onset of neonatal respiratory distress (PCD median = 12 hours, control median = 1 hour, P < .001), and higher frequency of lobar collapse and situs inversus (PCD = 70% and 48% respectively, control = 0% for both, P < .001). Situs inversus, lobar collapse, or oxygen need for >2 days had 87% (95% confidence interval: 74-94) sensitivity and 96% (95% confidence interval: 85-99) specificity for PCD.

CONCLUSIONS

When encountering term neonates with unexplained respiratory distress, clinicians should consider PCD in those with lobar collapse, situs inversus, and/or prolonged oxygen therapy (>2 days).

Genetics, diagnosis, and future treatment strategies for primary ciliary dyskinesia

INTRODUCTION

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous recessive disorder resulting in chronic oto-sino-pulmonary disease. While PCD is estimated to occur in 1 in 20,000 individuals, fewer than 1,000 patients in the US have a well-established diagnosis.

AREAS COVERED

We provide an overview of the clinical manifestations of PCD, describe the evolution of diagnostic methods, and critique the literature on management of PCD.

EXPERT OPINION

Although interest in clinical studies in non-CF bronchiectasis has increased in recent years, some of whom enroll patients with PCD, the literature regarding therapy for PCD as a distinct entity is lacking, as the numbers are small, and there have been no sub-analyses published. However, with improved screening and diagnostic methods, the development of clinical and research consortiums, and actively enrolling registries of PCD patients, the environment is conducive to perform longitudinal studies of disease course and therapeutic studies to alter that course.

Pathogenesis and risk factors for nontuberculous mycobacterial lung disease

Nontuberculous mycobacteria (NTM) infections are broadly classified as skin and soft tissue infections, isolated lung disease, and visceral or disseminated disease. The degree of underlying immune abnormalities varies between each classification. Skin and soft tissue infections are usually the result of iatrogenic or accidental inoculation of NTM in otherwise normal hosts. Visceral and disseminated NTM disease invariably occurs in individuals with more severe immunosuppression. Although the focus of this article is to discuss the pathogenesis of NTM lung disease, the risk factors of visceral/disseminated NTM disease are also summarized, as they provide insights into host-defense mechanisms against these organisms.

Recent advances in primary ciliary dyskinesia genetics

Primary ciliary dyskinesia (PCD) is a rare genetically heterogeneous disorder caused by the abnormal structure and/or function of motile cilia. The PCD diagnosis is challenging and requires a well-described clinical phenotype combined with the identification of abnormalities in ciliary ultrastructure and/or beating pattern as well as the recognition of genetic cause of the disease. Regarding the pace of identification of PCD-related genes, a rapid acceleration during the last 2-3 years is notable. This is the result of new technologies, such as whole-exome sequencing, that have been recently applied in genetic research. To date, PCD-causative mutations in 29 genes are known and the number of causative genes is bound to rise. Even though the genetic causes of approximately one-third of PCD cases still remain to be found, the current knowledge can already be used to create new, accurate genetic tests for PCD that can accelerate the correct diagnosis and reduce the proportion of unexplained cases. This review aims to present the latest data on the relations between ciliary structure aberrations and their genetic basis.

Recent advances in primary ciliary dyskinesia genetics

Primary ciliary dyskinesia (PCD) is a rare genetically heterogeneous disorder caused by the abnormal structure and/or function of motile cilia. The PCD diagnosis is challenging and requires a well-described clinical phenotype combined with the identification of abnormalities in ciliary ultrastructure and/or beating pattern as well as the recognition of genetic cause of the disease. Regarding the pace of identification of PCD-related genes, a rapid acceleration during the last 2–3 years is notable. This is the result of new technologies, such as whole-exome sequencing, that have been recently applied in genetic research. To date, PCD-causative mutations in 29 genes are known and the number of causative genes is bound to rise. Even though the genetic causes of approximately one-third of PCD cases still remain to be found, the current knowledge can already be used to create new, accurate genetic tests for PCD that can accelerate the correct diagnosis and reduce the proportion of unexplained cases. This review aims to present the latest data on the relations between ciliary structure aberrations and their genetic basis.

Nasal nitric oxide screening for primary ciliary dyskinesia: systematic review and meta-analysis

Nasal nitric oxide (nNO) concentrations are low in patients with primary ciliary dyskinesia (PCD) providing a noninvasive screening test.

We conducted a systematic review of the literature to examine the utility of nNO in screening for PCD, in particular 1) different respiratory manoeuvres during sampling (velum closure, tidal breathing, etc.), 2) accuracy in screening young/uncooperative children, 3) stationary versus portable analysers, and 4) nNO in “atypical” PCD.

96 papers were assessed according to modified PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria and 22 were included in this review.

Meta-analysis of 11 studies comparing nNO during a velum closure breath hold gave a mean±sd nNO of 19.4±18.6 nL·min-1 in PCD (n = 478) and 265.0±118.9 nL·min-1 in healthy controls (n = 338). Weighted mean difference for PCD versus healthy controls was 231.1 nL·min-1 (95% CI 193.3–268.9; n = 338) and 114.1 nL·min-1 (95% CI 101.5–126.8; n = 415) for PCD versus cystic fibrosis. Five studies of nNO measurement during tidal breathing demonstrated that this is an acceptable manoeuvre in young children where velum closure is not possible, but the discriminatory value was reduced. Four small studies of portable NO analysers suggest these are reliable tools for screening for PCD. However, nNO must be interpreted alongside clinical suspicion. Future studies should focus on standardising sampling techniques and reporting.

Mycobacterium abscessus Lung Disease in a Patient with Kartagener Syndrome

Primary ciliary dyskinesia (PCD) is characterized by the congenital impairment of mucociliary clearance. When accompanied by situs inversus, chronic sinusitis and bronchiectasis, PCD is known as Kartagener syndrome. The main consequence of impaired ciliary function is a reduced mucus clearance from the lungs, and susceptibility to chronic respiratory infections due to opportunistic pathogens, including nontuberculous mycobacteria (NTM). There has been no report of NTM lung disease combined with Kartagener syndrome in Korea. Here, we report an adult patient with Kartagener syndrome complicated with Mycobacterium abscessus lung disease. A 37-year-old female presented to our hospital with chronic cough and sputum. She was ultimately diagnosed with M. abscessus lung disease and Kartagener syndrome. M. abscessus was repeatedly isolated from sputum specimens collected from the patient, despite prolonged antibiotic treatment. The patient's condition improved and negative sputum culture conversion was achieved after sequential bilateral pulmonary resection.

Nontuberculous mycobacteria in diffuse panbronchiolitis

BACKGROUND AND OBJECTIVE

Nontuberculous mycobacterial (NTM) lung disease secondary to cystic fibrosis (CF) has been reported, but there is limited data about NTM prevalence in non-CF bronchiectasis. We retrospectively investigated the prevalence of NTM associated with diffuse panbronchiolitis (DPB), a disorder also characterized by reduced mucociliary clearance with bronchiectasis.

METHODS

We reviewed mycobacterial cultures, patient characteristics and computed tomography findings of 33 patients with DPB between January 2000 and December 2012. Prevalence was based on at least one positive NTM culture.

RESULTS

Mean patient age was 51.5 years. During a mean 162.8-month follow-up, the prevalence of NTM in sputum was 21.2% (seven patients). Of the seven positive patients, six had Mycobacterium avium complex, one had M. kansasii and M. chelonae co-cultured with M. avium complex. Three patients were positive twice, and two had positive smears. The mean time from DPB diagnosis to the first positive result was 194.6 months. NTM-positive patients tended to have lower forced expiratory volume in 1 s (% predicted) than NTM-negative patients (50.0% vs 77.3%, P = 0.03), but there were no radiological or clinical differences between the two groups.

CONCLUSIONS

Our observations suggest that NTM is found more often in DPB. Defects of mucociliary clearance may predispose individuals to NTM infection.

Standardizing nasal nitric oxide measurement as a test for primary ciliary dyskinesia

RATIONALE

Several studies suggest that nasal nitric oxide (nNO) measurement could be a test for primary ciliary dyskinesia (PCD), but the procedure and interpretation have not been standardized.

OBJECTIVES

To use a standard protocol for measuring nNO to establish a disease-specific cutoff value at one site, and then validate at six other sites.

METHODS

At the lead site, nNO was prospectively measured in individuals later confirmed to have PCD by ciliary ultrastructural defects (n = 143) or DNAH11 mutations (n = 6); and in 78 healthy and 146 disease control subjects, including individuals with asthma (n = 37), cystic fibrosis (n = 77), and chronic obstructive pulmonary disease (n = 32). A disease-specific cutoff value was determined, using generalized estimating equations (GEEs). Six other sites prospectively measured nNO in 155 consecutive individuals enrolled for evaluation for possible PCD.

MEASUREMENTS AND MAIN RESULTS

At the lead site, nNO values in PCD (mean ± standard deviation, 20.7 ± 24.1 nl/min; range, 1.5-207.3 nl/min) only rarely overlapped with the nNO values of healthy control subjects (304.6 ± 118.8; 125.5-867.0 nl/min), asthma (267.8 ± 103.2; 125.0-589.7 nl/min), or chronic obstructive pulmonary disease (223.7 ± 87.1; 109.7-449.1 nl/min); however, there was overlap with cystic fibrosis (134.0 ± 73.5; 15.6-386.1 nl/min). The disease-specific nNO cutoff value was defined at 77 nl/minute (sensitivity, 0.98; specificity, >0.999). At six other sites, this cutoff identified 70 of the 71 (98.6%) participants with confirmed PCD.

CONCLUSIONS

Using a standardized protocol in multicenter studies, nNO measurement accurately identifies individuals with PCD, and supports its usefulness as a test to support the clinical diagnosis of PCD.

Primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an autosomal recessive disorder of cilia structure and function, leading to chronic infections of the respiratory tract, fertility problems and disorders of organ laterality. Making a definitive diagnosis is challenging, utilizing characteristic phenotypes, ciliary functional and ultra-structural defects in addition to newer screening tools such as nasal nitric oxide and genetic testing. There are 21 known PCD causing genes and in the future, comprehensive genetic testing may help diagnosis young infants prior to developing symptoms thus improving survival. Therapy includes surveillance of pulmonary function and microbiology in addition to, airway clearance, antibiotics and early referral to bronchiectasis centers. Standardized care at specialized centers using a multidisciplinary approach is likely to improve outcomes. In conjunction with the PCD foundation and lead investigators and clinicians are developing a network of PCD clinical centers to coordinate the effort in North America and Europe. As the network grows, care and knowledge will undoubtedly improve.

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.

A new tool improves diagnostic test performance for transmission em evaluation of axonemal dynein arms

Abstract Diagnosis of primary ciliary dyskinesia (PCD) by identification of dynein arm loss in transmission electron microscopy (TEM) images can be confounded by high background noise due to random electron-dense material within the ciliary matrix, leading to diagnostic uncertainty even for experienced morphologists. The authors developed a novel image analysis tool to average the axonemal peripheral microtubular doublets, thereby increasing microtubular signal and reducing random background noise. In a randomized, double-blinded study that compared two experienced morphologists and three different diagnostic approaches, they found that use of this tool led to improvement in diagnostic TEM test performance.

Follicular bronchiolitis in primary ciliary dyskinesia

Ciliary dysfunction in primary ciliary dyskinesia (PCD) may be associated with bronchiolitis. Diffuse bronchiolitis has been reported in a subset of PCD patients who have Kartagener's syndrome in Japan. We report a case of follicular bronchiolitis (FB) in a case of PCD presenting with recurrent episodes of cough, dyspnea, and bronchiectasis. This may motivate researchers to study rarer variants and presentations in 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.

Primary Ciliary Dyskinesia: An Update on New Diagnostic Modalities and Review of the Literature

Primary ciliary dyskinesia (PCD) is a genetic condition affecting approximately 1 in 15,000-20,000 individuals, and the majority of cases exhibit an autosomal recessive inheritance pattern. However, genetic heterogenicity is seen in PCD and reflects the complexity of ciliary structure and biogenesis. There have been many recent advances in the diagnosis and management of PCD in the last few years, including advanced genetic sequencing, nasal nitric oxide assay, and ciliary motility tests. This article focuses on the ultrastructure and pathophysiology of ciliary dyskinesias, along with a review of clinical features, screening, and diagnostic tests. It also reflects upon the diagnostic challenge caused by the diverse clinical presentation, which will be of great value to pediatricians for considering PCD in their differential list, henceforth leading to early recognition and management, along with awareness of the recent advances in the field of genetics and other techniques for diagnosis of this condition.

Comparison of conventional pulmonary rehabilitation and high-frequency chest wall oscillation in primary ciliary dyskinesia

BACKGROUND

Enhancement of mucociliary clearance by pulmonary rehabilitation (PR) is advocated in primary ciliary dyskinesia (PCD). Our primary aim was to compare the efficacy and safety of postural drainage, percussion and vibration [conventional PR (CPR)], and high frequency chest wall oscillation (HFCWO) by studying change in pulmonary function. Our secondary aim was to evaluate patient preferences regarding the two methods.

METHODS

This was a controlled randomized crossover study. PCD patients between the ages of 7 and 18 years were assigned to two groups, first group performed airway clearance with CPR at hospital for 5 days and after a 2-day washout period HFCWO was applied to the same group at home. HFCWO was applied first to the other group and then these patients were hospitalized for CPR. The primary outcome measure of the study was pulmonary function test (PFT). The secondary outcomes were pulse arterial oxygen saturation (SpO2 ) and the perceived efficiency and comfort level.

RESULTS

PFT values of patients increased significantly after both PR methods (before/after): CPR: FVC: 77.0 ± 14.1/81.8 ± 13.0 (P = 0.002); FEV1 : 72.9 ± 14.8/78.7 ± 13.5 (P = 0.001); PEF: 73.8 ± 14.5/82.5 ± 14.5 (P = 0.001); FEF25-75 : 68.6 ± 27.6/74.9 ± 29.3 (P = 0.007).

HFCWO FVC

75.1 ± 15.3/80.3 ± 13.9 (P = 0.002); FEV1 : 71.4 ± 16/77.4 ± 14.6 (P = 0.001); PEF: 70.9 ± 18.0/78.3 ± 17.7 (P = 0.002); FEF25-75 : 70.5 ± 23.4/76.4 ± 25.6 (P = 0.006). There were no significant differences in % predicted FVC, FEV1 , PEF, and FEF25-75 increased values with CPR and HFCWO. HFCWO was found more comfortable (P = 0.04). Two PR methods were found efficient and no desaturation occurred during PR.

CONCLUSIONS

PFTs were significantly increased after both PR methods. There were no differences in PFTs and SpO2 between the CPR and HFCWO groups. Both PR methods were found efficient. HFCWO was found more comfortable. HFCWO may be an option in patients with chronic pulmonary disease and low adherence to PR.

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.

Generation of multiciliated cells in functional airway epithelia from human induced pluripotent stem cells

Despite therapeutic advancement, pulmonary disease still remains a major cause of morbidity and mortality around the world. Opportunities to study human lung disease either in vivo or in vitro are currently limited. Using induced pluripotent stem cells (iPSCs), we generated mature multiciliated cells in a functional airway epithelium. Robust multiciliogenesis occurred when notch signaling was inhibited and was confirmed by (i) the assembly of multiple pericentrin-stained centrioles at the apical surface, (ii) expression of transcription factor forkhead box protein J1, and (iii) presence of multiple acetylated tubulin-labeled cilia projections in individual cells. Clara, goblet, and basal cells were all present, confirming the generation of a complete polarized epithelial-cell layer. Additionally, cAMP-activated and cystic fibrosis transmembrane regulator inhibitor 172-sensitive cystic fibrosis transmembrane regulator currents were recorded in isolated epithelial cells. Our report demonstrating the generation of mature multiciliated cells in respiratory epithelium from iPSCs is a significant advance toward modeling a number of human respiratory diseases in vitro.

Sleep disordered breathing and airway disease in primary ciliary dyskinesia

BACKGROUND AND OBJECTIVE

Sleep-disordered breathing (SDB) may develop in primary ciliary dyskinesia (PCD), leading to these diseases worsening one another.

METHODS

Sixteen stable PCD patients (4.9-17.2 years) and 42 controls underwent overnight respiratory polysomnography (rPSG) and Sleep Disturbances Scale for Children (SDSC). In PCD we assessed nasal endoscopy, pulmonary function tests and chest high-resolution computed tomography (HRCT).

RESULTS

Compared with controls, PCD had higher obstructive apnoea (4.7 vs 0.2, P < 0.001), central apnoea (0.8 vs 0.2, P < 0.001), hypopnoea (1.8 vs 0.2, P < 0.001), apnoea-hypopnoea (7.8 vs 0.6, P < 0.001), oxygen desaturation indexes (ODI; 0.7 vs 0.2, P = 0.002), and mean oxygen desaturation (4% vs 1%, P < 0.001), while mean and nadir oxygen saturation (97.1% vs 98.1, P < 0.001) (93% vs 97.2%, P < 0.001) were lower, respectively. In PCD, SDSC was unrelated to rPSG (P > 0.05), with total score and subscores of disorders in initiating and maintaining sleep, and sleep-wake transition lower than controls. PCD patients had chronic rhinosinusitis (100%) and adenoidal hypertrophy (50%). Total HRCT score was 7 (range 0-14). ODI correlated with functional residual capacity (r = 0.8, P = 0.02), total HRCT (r = 0.6, P = 0.03) and peribronchial thickening scores (r = 0.7, P = 0.02). Oxygen saturation was associated with bronchiectasis severity score (r = -0.6, P = 0.02).

CONCLUSIONS

PCD's parents may underestimate SDB. As nocturnal desaturation is associated with lung function and structure abnormalities, SDB may significantly contribute to pulmonary morbidity.

Gene mutations in primary ciliary dyskinesia related to otitis media

Otitis media with effusion (OME) is the most common cause of conductive hearing loss in children and is strongly associated with primary ciliary dyskinesia (PCD). Approximately half of the children with PCD require otolaryngology care, posing a major problem in this population. Early diagnosis of PCD is critical in these patients to minimise the collateral damage related to OME. The current gold standard for PCD diagnosis requires determining ciliary structure defects by transmission electron microscopy (TEM) or clearly documenting ciliary dysfunction via digital high-speed video microscopy (DHSV). Although both techniques are useful for PCD diagnosis, they have limitations and need to be supported by new methodologies, including genetic analysis of genes related to PCD. In this article, we review classical and recently associated mutations related to ciliary alterations leading to PCD, which can be useful for early diagnosis of the disease and subsequent early management of OME.

Pulmonary function testing in children and infants

Pulmonary function testing is performed in children and infants with the aim of documenting lung development with age and making diagnoses of lung diseases. In children and infants with an established lung disease, pulmonary function is tested to assess the disease progression and the efficacy of therapy. It is difficult to carry out the measurements in this age group without disturbances, so obtaining results of good quality and reproducibility is challenging. Young children are often uncooperative during the examinations. This is partly related to their young age but also due to the long testing duration and the unpopular equipment. We address a variety of examination techniques for lung function assessment in children and infants in this review. We describe the measuring principles, examination procedures, clinical findings and their interpretation, as well as advantages and limitations of these methods. The comparability between devices and centres as well as the availability of reference values are still considered a challenge in many of these techniques. In recent years, new technologies have emerged allowing the assessment of lung function not only on the global level but also on the regional level. This opens new possibilities for detecting regional lung function heterogeneity that might lead to a better understanding of respiratory pathophysiology in children.

Coexistence of two rare genetic disorders: Kartagener syndrome and familial Mediterranean fever

Primary ciliary dyskinesia (PCD) is a rare disease, predominantly inherited as an autosomal recessive, with ciliary dysfunction leading to impaired mucociliary clearance, chronic airway infection and inflammation. Situs inversus totalis occurs in ~50 % of PCD patients and it is known as Kartagener syndome. Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent attacks of fever and peritonitis, pleuritis, arthritis, or erysipelas-like skin disease. FMF is caused by mutations in the MEFV gene which is located on chromosome 16p13.3. p.M680I, p.M694 V, p.M694I, p.V726A on exon 10 and p.E148Q on exon 2 are the most common mutations among FMF patients and these constitute 85 % of all. Homozygosity of R202Q polymorphism is strongly associated with FMF. We would like to present a case of Kartagener syndrome accompanied by FMF with R202Q polymorphism. Our case is the first in the literature indicating the accidental coexistence of FMF and Kartagener syndrome.

Auditory processing disorders associated with a case of Kartagner's syndrome

Kartagner's syndrome is a rare autosomal recessive disorder characterized by sinusitis, bronchiectasis and situs inversus. Otitis media is seen in 95% of the individuals with this syndrome due to recurrent respiratory infections and dysfunctional cilia in the middle ear. Earlier research reported the presence of structural and functional deficits in the auditory brainstem following long standing otitis media. However, no such findings have been reported in individuals with this syndrome. Thus, the present case report highlights the results of various audiological tests with special emphasis on investigating the auditory processing abilities in a known case of Kartagner's syndrome. In order to accomplish the aim, the audiological test battery was carried out on a 42 year old male patient diagnosed as having Kartagner's syndrome. The basic audiological tests, including immittance audiometry, pure tone audiometry, otoacoustic emission and auditory brainstem response (using click stimulus) results indicated the presence of mild to moderate mixed hearing loss in both ears. However, results of the auditory brainstem response (using speech stimulus) pointed toward abnormal speech processing skills. Thus, the behavioral test battery approach (including speech perception in noise test, gap detection test, temporal modulation transfer function test and duration pattern test) was followed and the findings suggested presence of auditory closure and temporal processing deficit. The outcome of the case study recommends that a complete test battery approach involving psychoacoustic tests should be used to assess such cases and auditory rehabilitation should be suggested accordingly.

Primary ciliary dyskinesia: critical evaluation of clinical symptoms and diagnosis in patients with normal and abnormal ultrastructure

Background

Primary ciliary dyskinesia (PCD) is a rare disorder with variable disease progression. To date, mutations in more than 20 different genes have been found. At present, PCD subtypes are described according to the ultrastructural defect on transmission electron microscopy (TEM) of the motile cilia. PCD with normal ultrastructure (NU) is rarely reported because it requires additional testing. Biallelic mutations in DNAH11 have been described as one cause of PCD with NU.

The aim of our study was to describe the clinical characteristics of a large population of patients with PCD, in relation to the ultrastructural defect. Additionally, we aimed to demonstrate the need for biopsy and cell culture to reliably diagnose PCD, especially the NU subtype.

Methods

We retrospectively analyzed data from 206 patients with PCD. We compared the clinical characteristics, lung function, microbiology and imaging results of 68 patients with PCD and NU to those of 90 patients with dynein deficiencies and 41 patients with central pair abnormalities. In addition, we aimed to demonstrate the robustness of the diagnosis of the NU subtype in cell culture by data from genetic analysis.

Results

PCD with NU comprised 33% (68/206) of all patients with PCD. Compared to other subtypes, patients with PCD and NU had a similar frequency of upper and lower respiratory tract problems, as well as similar lung function and imaging. With the currently widely applied approach, without cell culture, the diagnosis would have been missed in 16% (11/68) of patients with NU. Genetic analysis was performed in 29/68 patients with PCD and NU, and biallelic mutations were found in 79% (23/29) of tested patients.

Conclusions

We reported on the clinical characteristics of a large population of patients with PCD and NU. We have shown that systematic performance of biopsy and cell culture increases sensitivity to detect PCD, especially the subtype with NU.

PCD with NU has similar clinical characteristics as other PCD types and requires biopsy plus ciliogenesis in culture for optimal diagnostic yield.

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 (&lt; 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.

Chromothripsis: Basis of a Concurrent Unusual Association between Myelodysplastic Syndrome and Primary Ciliary Dyskinesia

A 20 year old male was initially diagnosed suffering from Primary ciliary dyskinesia with symptoms of bronchiectasis, severe frontal, maxillary and ethmoid sinus disease. At the age of 20, the patient was also diagnosed with Myelodysplastic syndrome requiring Bone marrow transplant due to the advanced stage at time of presentation. Primary ciliary dyskinesia and Myelodsyplastic syndrome are both rare clinical conditions found in the general population, especially in young adults. This rare combination of disorders has never been reported in literature to the best of the author's knowledge. The presence of an advanced cancer and a genetic abnormality due to two deletions occurring in two arms of the same chromosome can be explained on the base of chromothripsis. A number of evidences have been published in the literature, about multiple deletions in chromosome 5 and advanced stages of MDS being associated with chromothripsis however this is the first case report on two deletions in chromosome 7 giving rise to two different clinical entities requiring multiple modes of management.

Enhanced response to pulmonary Streptococcus pneumoniae infection is associated with primary ciliary dyskinesia in mice lacking Pcdp1 and Spef2

Background

Lower airway abnormalities are common in patients with primary ciliary dyskinesia (PCD), a pediatric syndrome that results from structural or functional defects in motile cilia. Patients can suffer from recurrent bacterial infection in the lung, bronchiectasis, and respiratory distress in addition to chronic sinusitis, otitis media, infertility, and laterality defects. However, surprisingly little is known about the pulmonary phenotype of mouse models of this disorder.

Results

The pulmonary phenotype of two mouse models of PCD, nm1054 and bgh, which lack Pcdp1 and Spef2, respectively, was investigated by histological and immunohistochemical analysis. In addition, both models were challenged with Streptococcus pneumoniae, a common respiratory pathogen found in the lungs of PCD patients. Histopathological analyses reveal no detectable cellular, developmental, or inflammatory abnormalities in the lower airway of either PCD model. However, exposure to S. pneumoniae results in a markedly enhanced inflammatory response in both models. Based on analysis of inflammatory cells in bronchoalveolar lavage fluid and flow cytometric analysis of cytokines in the lung, the bgh model shows a particularly dramatic lymphocytic response by 3 days post-infection compared to the nm1054 model or wild type animals.

Conclusions

Defects in ciliary motility result in a severe response to pulmonary infection. The PCD models nm1054 and bgh are distinct and clinically relevant models for future studies investigating the role of mucociliary clearance in host defense.

Lung clearance index and high-resolution computed tomography scores in primary ciliary dyskinesia

RATIONALE

Lung clearance index (LCI) is a more sensitive measure of lung function than spirometry in cystic fibrosis (CF) and correlates well with abnormalities in high-resolution computed tomography (HRCT) scanning. We hypothesized LCI would be equally sensitive to lung disease in primary ciliary dyskinesia (PCD).

OBJECTIVES

To test the relationships between LCI, spirometry, and HRCT in PCD and to compare them to the established relationships in CF.

METHODS

Cross-sectional study of 127 patients with CF and 33 patients with PCD, all of whom had spirometry and LCI, of which a subset of 21 of each had HRCT performed. HRCT was scored for individual features and these features compared with physiological parameters.

MEASUREMENTS AND MAIN RESULTS

Unlike in CF, and contrary to our hypothesis, there was no correlation between spirometry and LCI in PCD and no correlation between HRCT features and LCI or spirometry in PCD.

CONCLUSIONS

We show for the first time that HRCT, spirometry, and LCI have different relationships in different airway diseases and that LCI does not appear to be a sensitive test of airway disease in advanced PCD. We hypothesize that this results from dissimilarities between the components of large and small airway disease in CF and PCD. These differences may in part lead to the different prognosis in these two neutrophilic airway diseases.

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.

Treatment and outcomes of chronic rhinosinusitis in children with primary ciliary dyskinesia: where is the evidence? A qualitative systematic review

BACKGROUND

Consensus on treatment of chronic rhinosinusitis (CRS) in children with primary ciliary dyskinesia (PCD) is limited. We sought to synthesize the best available evidence pertaining to treatment and outcomes of CRS in children with PCD.

METHODS

This work is a systematic review of PubMed and EMBASE for studies pertaining to treatment and outcomes of CRS in children with PCD in a 20-year period. Two reviewers independently extracted information on study design, setting, medical or surgical therapy for CRS, and treatment outcomes.

RESULTS

Twelve studies from 8 countries were included for analysis: (3 retrospective cohorts, 2 prospective cohorts, 2 cross-sectional, 1 case series, and 4 case reports). The number of patients with PCD ranged from 1 to 78. Medical treatment included oral antibiotics, intranasal steroids, and oral steroids. Surgical treatment was mentioned in 8 studies, with endoscopic sinus surgery (ESS) described in 3 of 8. Outcome measures were rarely defined but included the 20-item Sino-Nasal Outcome Test (SNOT-20) questionnaire (1/12), symptom questionnaire (1/12), decreased recurrent pneumonia (1/12), and subjective report of CRS symptoms. No randomized, controlled, or long-term prospective cohort studies were identified, and no study employed a disease-specific, pediatric-validated instrument to measure outcomes of therapy.

CONCLUSION

There is a paucity of evidence pertaining to CRS treatment or outcomes in children with PCD. Given the rare prevalence of PCD and the insufficient evidence pertaining to treatment effectiveness for CRS, we propose an international, multicenter database to prospectively track data pertaining to diagnosis, treatment, and outcomes of CRS for children with PCD. This effort would encourage implementation of validated and standardized outcome measures.

Zebrafish Ciliopathy Screen Plus Human Mutational Analysis Identifies C21orf59 and CCDC65 Defects as Causing Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD) is caused when defects of motile cilia lead to chronic airway infections, male infertility, and situs abnormalities. Multiple causative PCD mutations account for only 65% of cases, suggesting that many genes essential for cilia function remain to be discovered. By using zebrafish morpholino knockdown of PCD candidate genes as an in vivo screening platform, we identified c21orf59, ccdc65, and c15orf26 as critical for cilia motility. c21orf59 and c15orf26 knockdown in zebrafish and planaria blocked outer dynein arm assembly, and ccdc65 knockdown altered cilia beat pattern. Biochemical analysis in Chlamydomonas revealed that the C21orf59 ortholog FBB18 is a flagellar matrix protein that accumulates specifically when cilia motility is impaired. The Chlamydomonas ida6 mutant identifies CCDC65/FAP250 as an essential component of the nexin-dynein regulatory complex. Analysis of 295 individuals with PCD identified recessive truncating mutations of C21orf59 in four families and CCDC65 in two families. Similar to findings in zebrafish and planaria, mutations in C21orf59 caused loss of both outer and inner dynein arm components. Our results characterize two genes associated with PCD-causing mutations and elucidate two distinct mechanisms critical for motile cilia function: dynein arm assembly for C21orf59 and assembly of the nexin-dynein regulatory complex for CCDC65.

Mutations in SPAG1 cause primary ciliary dyskinesia associated with defective outer and inner dynein arms

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous, autosomal-recessive disorder, characterized by oto-sino-pulmonary disease and situs abnormalities. PCD-causing mutations have been identified in 20 genes, but collectively they account for only ∼65% of all PCDs. To identify mutations in additional genes that cause PCD, we performed exome sequencing on three unrelated probands with ciliary outer and inner dynein arm (ODA+IDA) defects. Mutations in SPAG1 were identified in one family with three affected siblings. Further screening of SPAG1 in 98 unrelated affected individuals (62 with ODA+IDA defects, 35 with ODA defects, 1 without available ciliary ultrastructure) revealed biallelic loss-of-function mutations in 11 additional individuals (including one sib-pair). All 14 affected individuals with SPAG1 mutations had a characteristic PCD phenotype, including 8 with situs abnormalities. Additionally, all individuals with mutations who had defined ciliary ultrastructure had ODA+IDA defects. SPAG1 was present in human airway epithelial cell lysates but was not present in isolated axonemes, and immunofluorescence staining showed an absence of ODA and IDA proteins in cilia from an affected individual, thus indicating that SPAG1 probably plays a role in the cytoplasmic assembly and/or trafficking of the axonemal dynein arms. Zebrafish morpholino studies of spag1 produced cilia-related phenotypes previously reported for PCD-causing mutations in genes encoding cytoplasmic proteins. Together, these results demonstrate that mutations in SPAG1 cause PCD with ciliary ODA+IDA defects and that exome sequencing is useful to identify genetic causes of heterogeneous recessive disorders.

Founder mutation in RSPH4A identified in patients of Hispanic descent with primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a rare, autosomal recessive, genetically heterogeneous disorder characterized by ciliary dysfunction resulting in chronic oto-sino-pulmonary disease, respiratory distress in term neonates, laterality (situs) defects, and bronchiectasis. Diagnosis has traditionally relied on ciliary ultrastructural abnormalities seen by electron microscopy. Mutations in radial spoke head proteins occur in PCD patients with central apparatus defects. Advances in genetic testing have been crucial in addressing the diagnostic challenge. Here, we describe a novel splice-site mutation (c.921+3_6delAAGT) in RSPH4A, which leads to a premature translation termination signal in nine subjects with PCD (seven families). Loss-of-function was confirmed with quantitative ciliary ultrastructural analysis, measurement of ciliary beat frequency and waveform, and transcript analysis. All nine individuals carrying c.921+3_6delAAGT splice-site mutation in RSPH4A were Hispanic with ancestry tracing to Puerto Rico. This mutation is a founder mutation and a common cause of PCD without situs abnormalities in patients of Puerto Rican descent.

Complexity, temporal stability, and clinical correlates of airway bacterial community composition in primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a genetic disease characterized by abnormalities in ciliary function, leading to compromised airway clearance and chronic bacterial infection of the upper and lower airways. The compositions of these infections and the relationships between their characteristics and disease presentation are poorly defined. We describe here the first systematic culture-independent evaluation of lower airway bacteriology in PCD. Thirty-three airway samples (26 from sputum, 7 from bronchoalveolar lavage [BAL] fluid) were collected from 24 PCD patients aged 4 to 73 years. 16S rRNA quantitative PCR and pyrosequencing were used to determine the bacterial loads and community compositions of the samples. Bacterial loads, which ranged from 1.3 × 10(4) to 5.2 × 10(9) CFU/ml, were positively correlated with age (P = 0.002) but not lung function. An analysis of ∼7,000 16S rRNA sequences per sample identified bacterial species belonging to 128 genera. The concurrently collected paired samples showed high bacterial community similarity. The mean relative abundance of the dominant genera was 64.5% (standard deviation [SD], 24.5), including taxa reported through standard diagnostic microbiology (members of the genera Pseudomonas, Haemophilus, and Streptococcus) and those requiring specific ex vivo growth conditions (members of the genera Prevotella and Porphyromonas). The significant correlations observed included a positive relationship between Pseudomonas aeruginosa relative abundance and age and a negative relationship between P. aeruginosa relative abundance and lung function. Members of the genus Ralstonia were also found to contribute substantially to the bacterial communities in a number of patients. Follow-up samples from a subset of patients revealed high levels of bacterial community temporal stability. The detailed microbiological characterization presented here provides a basis for the reassessment of the clinical management of PCD airway infections.

CCDC65 mutation causes primary ciliary dyskinesia with normal ultrastructure and hyperkinetic cilia

BACKGROUND

Primary ciliary dyskinesia (PCD) is a genetic disorder characterized by impaired ciliary function, leading to chronic sinopulmonary disease. The genetic causes of PCD are still evolving, while the diagnosis is often dependent on finding a ciliary ultrastructural abnormality and immotile cilia. Here we report a novel gene associated with PCD but without ciliary ultrastructural abnormalities evident by transmission electron microscopy, but with dyskinetic cilia beating.

METHODS

Genetic linkage analysis was performed in a family with a PCD subject. Gene expression was studied in Chlamydomonas reinhardtii and human airway epithelial cells, using RNA assays and immunostaining. The phenotypic effects of candidate gene mutations were determined in primary culture human tracheobronchial epithelial cells transduced with gene targeted shRNA sequences. Video-microscopy was used to evaluate cilia motion.

RESULTS

A single novel mutation in CCDC65, which created a termination codon at position 293, was identified in a subject with typical clinical features of PCD. CCDC65, an orthologue of the Chlamydomonas nexin-dynein regulatory complex protein DRC2, was localized to the cilia of normal nasal epithelial cells but was absent in those from the proband. CCDC65 expression was up-regulated during ciliogenesis in cultured airway epithelial cells, as was DRC2 in C. reinhardtii following deflagellation. Nasal epithelial cells from the affected individual and CCDC65-specific shRNA transduced normal airway epithelial cells had stiff and dyskinetic cilia beating patterns compared to control cells. Moreover, Gas8, a nexin-dynein regulatory complex component previously identified to associate with CCDC65, was absent in airway cells from the PCD subject and CCDC65-silenced cells.

CONCLUSION

Mutation in CCDC65, a nexin-dynein regulatory complex member, resulted in a frameshift mutation and PCD. The affected individual had altered cilia beating patterns, and no detectable ultrastructural defects of the ciliary axoneme, emphasizing the role of the nexin-dynein regulatory complex and the limitations of certain methods for PCD diagnosis.