Aline Tamalet

RPGR is mutated in patients with a complex X linked phenotype combining primary ciliary dyskinesia and retinitis pigmentosa.

Introduction: Primary ciliary dyskinesia (PCD) is a rare disease classically transmitted as an autosomal recessive trait and characterised by recurrent airway infections due to abnormal ciliary structure and function. To date, only two autosomal genes, DNAI1 and DNAH5 encoding axonemal dynein chains, have been shown to cause PCD with defective outer dynein arms. Here, we investigated one non-consanguineous family in which a woman with retinitis pigmentosa (RP) gave birth to two boys with a complex phenotype combining PCD, discovered in early childhood and characterised by partial dynein arm defects, and RP that occurred secondarily. The family history prompted us to search for an X linked gene that could account for both conditions. Results: We found perfect segregation of the disease phenotype with RP3 associated markers (Xp21.1). Analysis of the retinitis pigmentosa GTPase regulator gene (RPGR) located at this locus revealed a mutation (631_IVS6+9del) in the two boys and their mother. As shown by study of RPGR transcripts expressed in nasal epithelial cells, this intragenic deletion, which leads to activation of a cryptic donor splice site, predicts a severely truncated protein. Conclusion: These data provide the first clear demonstration of X linked transmission of PCD. This unusual mode of inheritance of PCD in patients with particular phenotypic features (that is, partial dynein arm defects and association with RP), which should modify the current management of families affected by PCD or RP, unveils the importance of RPGR in the proper development of both respiratory ciliary structures and connecting cilia of photoreceptors.

Loss-of-Function Mutations in LRRC6, a Gene Essential for Proper Axonemal Assembly of Inner and Outer Dynein Arms, Cause Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD) is a group of autosomal-recessive disorders resulting from cilia and sperm-flagella defects, which lead to respiratory infections and male infertility. Most implicated genes encode structural proteins that participate in the composition of axonemal components, such as dynein arms (DAs), that are essential for ciliary and flagellar movements; they explain the pathology in fewer than half of the affected individuals. We undertook this study to further understand the pathogenesis of PCD due to the absence of both DAs. We identified, via homozygosity mapping, an early frameshift in LRRC6, a gene that encodes a leucine-rich-repeat (LRR)-containing protein. Subsequent analyses of this gene mainly expressed in testis and respiratory cells identified biallelic mutations in several independent individuals. The situs inversus observed in two of them supports a key role for LRRC6 in embryonic nodal cilia. Study of native LRRC6 in airway epithelial cells revealed that it localizes to the cytoplasm and within cilia, whereas it is absent from cells with loss-of-function mutations, in which DA protein markers are also missing. These results are consistent with the transmission-electron-microscopy data showing the absence of both DAs in cilia or flagella from individuals with LRRC6 mutations. In spite of structural and functional similarities between LRRC6 and DNAAF1, another LRR-containing protein involved in the same PCD phenotype, the two proteins are not redundant. The evolutionarily conserved LRRC6, therefore, emerges as an additional player in DA assembly, a process that is essential for proper axoneme building and that appears to be much more complex than was previously thought.

Loss-of-Function Mutations in RSPH1 Cause Primary Ciliary Dyskinesia with Central-Complex and Radial-Spoke Defects

Primary ciliary dyskinesia (PCD) is a rare autosomal-recessive respiratory disorder resulting from defects of motile cilia. Various axonemal ultrastructural phenotypes have been observed, including one with so-called central-complex (CC) defects, whose molecular basis remains unexplained in most cases. To identify genes involved in this phenotype, whose diagnosis can be particularly difficult to establish, we combined homozygosity mapping and whole-exome sequencing in a consanguineous individual with CC defects. This identified a nonsense mutation in RSPH1, a gene whose ortholog in Chlamydomonas reinhardtii encodes a radial-spoke (RS)-head protein and is mainly expressed in respiratory and testis cells. Subsequent analyses of RSPH1 identified biallelic mutations in 10 of 48 independent families affected by CC defects. These mutations include splicing defects, as demonstrated by the study of RSPH1 transcripts obtained from airway cells of affected individuals. Wild-type RSPH1 localizes within cilia of airway cells, but we were unable to detect it in an individual with RSPH1 loss-of-function mutations. High-speed-videomicroscopy analyses revealed the coexistence of different ciliary beating patterns-cilia with a normal beat frequency but abnormal motion alongside immotile cilia or cilia with a slowed beat frequency-in each individual. This study shows that this gene is mutated in 20.8% of individuals with CC defects, whose diagnosis could now be improved by molecular screening. RSPH1 mutations thus appear as a major etiology for this PCD phenotype, which in fact includes RS defects, thereby unveiling the importance of RSPH1 in the proper building of CCs and RSs in humans.

Carcinoid and mucoepidermoid bronchial tumours in children

The aim of the study was to determine the characteristic features and outcome of carcinoid or mucoepidermoid tumours in children. A retrospective analysis of all patients treated for a carcinoid or mucoepidermoid tumour in France between 1984 and 2001 was performed. There were 11 cases of carcinoid tumour and 6 cases of mucoepidermoid tumour. The mean age of the patients was 10.5±3.0 years, with a range of 5 to 15 years. Twelve and 6 patients presented with evidence of bronchial obstruction and haemoptysis, respectively. Fibre optic bronchoscopy confirmed the presence of a bronchial tumour in all cases and endobronchial biopsies were diagnostic in 11 of 12 cases. A chest CT scan revealed the presence of a hypervascular tumour in 8 of 12 patients. The distribution of the location of the tumours was equal between the right and the left lung, and, in 9 cases, the airways were totally occluded by the tumour. Complete surgical resection (lobectomy in 15 patients and pneumonectomy in 2 patients) was performed in all cases without pre-operative chemotherapy or radiotherapy. The mean duration of follow-up was 4.0±3.0 years. In 2 patients, auscultation assymetry and an episode of haemoptysis revealed the recurrence of a mucoepidermoid tumour, successfully cured by removal of the tumour and chemotherapy and radiotherapy in one child. No death was observed. Conclusion:Pulmonary carcinoid and mucoepidermoid tumours are rare in children. Bronchoscopic removal should not be performed. With aggressive surgical therapy, the prognosis is excellent. Fibre optic bronchoscopy confirms the presence of an endobronchial mass. A biopsy is needed for diagnosis and complete surgical removal is the treatment of choice. Long-term results are excellent but a clinical follow-up is recommended.

Otologic features in children with primary ciliary dyskinesia.

OBJECTIVES To analyze otologic features in patients with primary ciliary dyskinesia (PCD) aged 0 to 18 years and to evaluate the correlation between ultrastructural defects and severity of otologic features. DESIGN Retrospective study. SETTING Pediatric referral center. PATIENTS Fifty-eight patients with PCD were evaluated in the following 4 age intervals: group 1, preschool (≤ 5 years [n = 47]); group 2, school (6-11 years [n = 50]); group 3, teenagers (12-17 years [n = 34]); and group 4, young adults (≥ 18 years; 27 years for the oldest [n = 10]). Follow-up was 2 to 6 years in each age group; 26 patients had total follow-up of more than 12 years. Ultrastructural defects occurred in the outer dynein arm (n = 33), the inner dynein arm (n = 13), and the central complex (n = 11). One patient had typical Kartagener syndrome with typical PCD features but normal ciliary ultrastructure. MAIN OUTCOME MEASURES Frequency of acute otitis media, otitis media with effusion, otorrhea, chronic otitis media, hearing loss, and middle ear surgery and type of antibiotic regimen according to age and type of defect. RESULTS Recurrent acute otitis media decreased from group 1 (32 of 47 [68%]) to group 4 (0 of 10 [0%]) (P < .001). Otitis media with effusion was more severe in groups 1 through 3 than in group 4 (P = .02). Otorrhea decreased in group 4: 30% vs 80% (3 of 10 vs 36 of 41) in the other groups (P < .001). Half of the patients with tympanostomy tubes eventually had tympanic perforation. Hearing loss was moderate in groups 1 through 3 and mild in group 4. Continuous antibiotic therapy could be slightly reduced only in group 4. Central complex defect was a significant marker of severity for all these criteria. CONCLUSIONS Despite continuous antibiotic therapy, the middle ear condition in PCD remained severe throughout childhood, with improvement only after age 18 years. Armstrong grommet placement did not improve the middle ear condition. Central complex defect is a marker of severity.

Chronic interstitial lung disease in children: Response to high-dose intravenous methylprednisolone pulses

The prognosis for children with chronic interstitial lung disease is poor and the mortality rate is high, especially in infants. This explains the many therapeutical protocols which have been proposed and investigated by several authors. In the present work, we evaluated the response of three infants with idiopathic pulmonary fibrosis to high‐dose intravenous prednisolone pulses. The patients were referred to the department at the age of 4, 17, and 3 months, respectively. The diagnosis was confirmed by open lung biopsy and intravenous pulse methyl prednisolone therapy was started with the following protocol: 300 mg/m2 methylprednisolone daily for 3 days, repeated every 4 to 6 weeks. Because of the extreme severity of the respiratory distress at the time of diagnosis, the intravenous pulse treatments were initially complemented by oral prednisone. Clinical improvement was noticed within 6 months with progressive correction of hypoxemia. After follow‐up for 3.5 to 4 years, with a total number of pulses of 37, 26, and 32, respectively, the children are symptom‐free and do not require oxygen supplementation. During this period, no side effects and no adrenal insufficiency could be documented. Based on current knowledge of steroid action, it can be speculated that the response to intermittent high‐dose intravenous methylprednisolone may explain the ability of this mode of hormone administration to maintain an adequate level of glucocorticoid receptor expression. More information and trials through multicenter collaborations are needed to assess therapeutical protocols of repeated high‐dose intravenous steroid treatment. Pediatr Pulmonol. 1998; 26:332–338.

Longitudinal lung function and structural changes in children with primary ciliary dyskinesia.

Functional and structural lung evaluations are part of the follow‐up of patients with primary ciliary dyskinesia (PCD). We aimed to evaluate transversal and longitudinal relationships between lung function test (LFT) and chest computed tomography (CT) in children with PCD, in stable clinical condition.

RSPH3 Mutations Cause Primary Ciliary Dyskinesia with Central-Complex Defects and a Near Absence of Radial Spokes

Primary ciliary dyskinesia (PCD) is a rare autosomal-recessive condition resulting from structural and/or functional defects of the axoneme in motile cilia and sperm flagella. The great majority of mutations identified so far involve genes whose defects result in dynein-arm anomalies. By contrast, PCD due to CC/RS defects (those in the central complex [CC] and radial spokes [RSs]), which might be difficult to diagnose, remains mostly unexplained. We identified non-ambiguous RSPH3 mutations in 5 of 48 independent families affected by CC/RS defects. RSPH3, whose ortholog in the flagellated alga Chlamydomonas reinhardtii encodes a RS-stalk protein, is mainly expressed in respiratory and testicular cells. Its protein product, which localizes within the cilia of respiratory epithelial cells, was undetectable in airway cells from an individual with RSPH3 mutations and in whom RSPH23 (a RS-neck protein) and RSPH1 and RSPH4A (RS-head proteins) were found to be still present within cilia. In the case of RSPH3 mutations, high-speed-videomicroscopy analyses revealed the coexistence of immotile cilia and motile cilia with movements of reduced amplitude. A striking feature of the ultrastructural phenotype associated with RSPH3 mutations is the near absence of detectable RSs in all cilia in combination with a variable proportion of cilia with CC defects. Overall, this study shows that RSPH3 mutations contribute to disease in more than 10% of PCD-affected individuals with CC/RS defects, thereby allowing an accurate diagnosis to be made in such cases. It also unveils the key role of RSPH3 in the proper building of RSs and the CC in humans.

Longitudinal lung function and structural changes in children with primary ciliary dyskinesia

Methods Data from children followed in the French National Center were retrospectively collected. Inclusion criteria were (i) definitive diagnosis of PCD, (ii) age less than 15 years at the beginning of follow-up, (iii) at least 8 years of followup and (iv) at least 2 couples of concurrent CT and LFT performed in stable clinical condition. Twenty children (median age 4.6 years, median follow-up 15.4 years) were included. Concurrent LFT (blood gas and spirometry) and CT (score) results were recorded.

Mucoviscidose: les stratégies thérapeutiques se multiplient

Resume Depuis la decouverte du gene defectueux dans la mucoviscidose, des progres tres rapides ont ete accomplis dans la comprehension des fonctions cellulaires de la proteine CFTR ( cystic fibrosis transmembrane conductance regulator ) et des mecanismes regulant son expression. A partir de la caracterisation des processus impliques dans la progression de la maladie au niveau pulmonaire, des projets therapeutiques varies ont ete developpes, fondes sur la therapie genique et sur l’utilisation de differents agents pharmacologiques. Certains de ces agents ont pour role de retablir une fonction CFTR adequate; d’autres agiraient en court-circuitant la proteine CFTR par induction de l’expression de proteines proches. Dans la presente mise au point, les strategies therapeutiques actuellement en cours d’investigation sont discutees