Research update for articles published in EJCI in 2011

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.

Clinical application of nasal nitric oxide measurement in pediatric airway diseases

Nitric oxide plays an important role in several physiological and pathophysiological processes in the respiratory tract. Different ways to measure nasal nitric oxide levels in children are currently available. The possibility of obtaining nasal nitric oxide measurement from relatively young children, combined with the availability of portable devices that can be used even in the office setting, opens new perspectives for nasal nitric oxide analysis in the pediatric daily practice. This review presents a synopsis about the current clinical applications of nasal nitric oxide measurement in the pediatric clinical practice. A total of 3,775 articles on the topic were identified, of which 883 duplicates were removed, and 2,803 were excluded based on review of titles and abstracts. Eighty-nine full text articles were assessed for eligibility and 32 additional articles were obtained from the reference lists of the retrieved studies. Since very low nasal nitric oxide levels are found in the majority of patients with primary ciliary dyskinesia, most publications support a central role for nasal nitric oxide to screen the disease, and indicate that it is a very helpful first-line tool in the real-life work-up in all age groups. Decreased nasal nitric oxide concentration is also typical of cystic fibrosis, even though nasal nitric oxide is not as low as in primary ciliary dyskinesia. In other upper airway disorders such as allergic rhinitis, rhinosinusitis, nasal polyposis, and adenoidal hypertrophy, clinical utility of nasal nitric oxide is still critically questioned and remains to be established. Since nNO determination is flow dependent, a general consensus from the major investigators in this area is highly desirable so that future studies will be performed with the same flow rate. A shared nNO methodology will enable to overcome the challenges that lie ahead in incorporating nNO measurement into the mainstream clinical setting of pediatric airway diseases.