Browsing by Subject "Kartagener Syndrome"

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    Accuracy of Nasal Nitric Oxide Measurement as a Diagnostic Test for Primary Ciliary Dyskinesia. A Systematic Review and Meta-analysis
    (ATS, 2017-07) Shapiro, Adam J.; Josephson, Maureen; Rosenfeld, Margaret; Yilmaz, Ozge; Davis, Stephanie D.; Polineni, Deepika; Guadagno, Elena; Leigh, Margaret W.; Lavergne, Valery; Pediatrics, School of Medicine
    Rationale: Primary ciliary dyskinesia (PCD) is a rare disorder causing chronic otosinopulmonary disease, generally diagnosed through evaluation of respiratory ciliary ultrastructure and/or genetic testing. Nasal nitric oxide (nNO) measurement is used as a PCD screening test because patients with PCD have low nNO levels, but its value as a diagnostic test remains unknown. Objectives: To perform a systematic review to assess the utility of nNO measurement (index test) as a diagnostic tool compared with the reference standard of electron microscopy (EM) evaluation of ciliary defects and/or detection of biallelic mutations in PCD genes. Data Sources: Ten databases were searched for reference sources from database inception through July 29, 2016. Data Extraction: Study inclusion was limited to publications with rigorous nNO index testing, reference standard diagnostic testing with EM and/or genetics, and calculable diagnostic accuracy information for cooperative patients (generally >5 yr old) with high suspicion of PCD. Synthesis: Meta-analysis provided a summary estimate for sensitivity and specificity and a hierarchical summary receiver operating characteristic curve. The Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to assess study quality, and Grading of Recommendations Assessment, Development, and Evaluation was used to assess the certainty of evidence. In 12 study populations (1,344 patients comprising 514 with PCD and 830 without PCD), using a reference standard of EM alone or EM and/or genetic testing, summary sensitivity was 97.6% (92.7–99.2) and specificity was 96.0% (87.9–98.7), with a positive likelihood ratio of 24.3 (7.6–76.9), a negative likelihood ratio of 0.03 (0.01–0.08), and a diagnostic odds ratio of 956.8 (141.2–6481.5) for nNO measurements. After studies using EM alone as the reference standard were excluded, the seven studies using an extended reference standard of EM and/or genetic testing showed a summary sensitivity of nNO measurements of 96.3% (88.7–98.9) and specificity of 96.4% (85.1–99.2), with a positive likelihood ratio of 26.5 (5.9–119.1), a negative likelihood ratio of 0.04 (0.01–0.12), and a diagnostic odds ratio of 699.3 (67.4–7256.0). Certainty of the evidence was graded as moderate. Conclusions: nNO is a sensitive and specific test for PCD in cooperative patients (generally >5 yr old) with high clinical suspicion for this disease. With a moderate level of evidence, this meta-analysis confirms that nNO testing using velum closure maneuvers has diagnostic accuracy similar to EM and/or genetic testing for PCD when cystic fibrosis is ruled out. Thus, low nNO values accompanied by an appropriate clinical phenotype could be used as a diagnostic PCD test, though EM and/or genetics will continue to provide confirmatory information.
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    Mutation of Growth Arrest Specific 8 Reveals a Role in Motile Cilia Function and Human Disease
    (Plos, 2016-07-29) Lewis, Wesley R.; Malarkey, Erik B.; Tritschler, Douglas; Bower, Raqual; Pasek, Raymond C.; Porath, Jonathan D.; Birket, Susan E.; Saunier, Sophie; Antignac, Corinne; Knowles, Michael R.; Leigh, Margaret W.; Zariwala, Maimoona A.; Challa, Anil K.; Keterson, Robert A.; Drummond, Iaian A.; Parant, John M.; Rowe, Steven M.; Hildebrandt, Friedhelm; Porter, Mary E.; Yoder, Bradley K.; Berbari, Nicolas F.; Department of Biology, School of Science
    Ciliopathies are genetic disorders arising from dysfunction of microtubule-based cellular appendages called cilia. Different cilia types possess distinct stereotypic microtubule doublet arrangements with non-motile or 'primary' cilia having a 9+0 and motile cilia have a 9+2 array of microtubule doublets. Primary cilia are critical sensory and signaling centers needed for normal mammalian development. Defects in their structure/function result in a spectrum of clinical and developmental pathologies including abnormal neural tube and limb patterning. Altered patterning phenotypes in the limb and neural tube are due to perturbations in the hedgehog (Hh) signaling pathway. Motile cilia are important in fluid movement and defects in motility result in chronic respiratory infections, altered left-right asymmetry, and infertility. These features are the hallmarks of Primary Ciliary Dyskinesia (PCD, OMIM 244400). While mutations in several genes are associated with PCD in patients and animal models, the genetic lesion in many cases is unknown. We assessed the in vivo functions of Growth Arrest Specific 8 (GAS8). GAS8 shares strong sequence similarity with the Chlamydomonas Nexin-Dynein Regulatory Complex (NDRC) protein 4 (DRC4) where it is needed for proper flagella motility. In mammalian cells, the GAS8 protein localizes not only to the microtubule axoneme of motile cilia, but also to the base of non-motile cilia. Gas8 was recently implicated in the Hh signaling pathway as a regulator of Smoothened trafficking into the cilium. Here, we generate the first mouse with a Gas8 mutation and show that it causes severe PCD phenotypes; however, there were no overt Hh pathway phenotypes. In addition, we identified two human patients with missense variants in Gas8. Rescue experiments in Chlamydomonas revealed a subtle defect in swim velocity compared to controls. Further experiments using CRISPR/Cas9 homology driven repair (HDR) to generate one of these human missense variants in mice demonstrated that this allele is likely pathogenic.