Primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an autosomal recessive disorder of cilia structure, function, and biogenesis leading to chronic infections of the respiratory tract, fertility problems, and disorders of organ laterality. The diagnosis can be challenging, using traditional tools such as characteristic clinical features, ciliary function, and ultrastructural defects and newer screening tools such as nasal nitric oxide levels and genetic testing add to the diagnostic algorithm. There are 32 known PCD-causing genes, and in the future, comprehensive genetic testing may screen young infants before developing symptoms, thus improving survival. Therapies include surveillance of pulmonary function and microbiology, in addition to airway clearance, antibiotics, and early referral to bronchiectasis centers. As with cystic fibrosis (CF), standardized care at specialized centers using a multidisciplinary approach likely improves outcomes. In conjunction with the CF foundation, the PCD foundation, with experienced investigators and clinicians, is developing a network of PCD clinical centers to coordinate the effort in North America and Europe. As the network grows, clinical care and knowledge will improve

Investigation of the possible role of a novel gene, DPCD, in primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an autosomal recessive disease caused by mutations that affect the proper function of cilia. Recently, deletion of DNA polymerase λ (Poll) in mice produced a phenotype characteristic of PCD (Kobayashi et al., 2002, Mol. Cell. Biol. 22:2769-2776). Because it is unclear how a mutation in a DNA polymerase would result in a specific defect in axonemes, the targeting construct was examined further. Analysis of the genomic region surrounding the Poll gene revealed an uncharacterized gene, named Dpcd, that is predicted to be transcribed from the opposite strand relative to Poll. The deletion of Poll would also remove the first exon of Dpcd. Because it is possible that the PCD phenotype observed is due to the absence of either gene, the expression of these genes during ciliogenesis of human airway epithelial cells was examined. Northern analysis demonstrated that DPCD expression increases during ciliated cell differentiation; the expression of POLL decreases. To examine directly whether DPCD is mutated in cases of human PCD, the complete coding sequence of DPCD was sequenced from 51 unrelated PCD patients. No disease-causing mutations were confirmed; however, one variant could not be excluded. Therefore, DPCD remains a novel candidate gene for PCD

Effect of aerosolized uridine-5'-triphosphate on airway clearance with cough in patients with primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a genetic disease characterized by abnormal ciliary structure and function and impaired mucociliary clearance. Because patients with PCD use cough clearance as an airway defense mechanism, we tested the hypothesis that aerosolized uridine-5'-triphosphate (UTP) would improve clearance during cough by its actions to stimulate CI secretion and mucin release by goblet cells. We measured clearance during cough in 12 patients with PCD (ages 14 to 71 yr, FEV1 43% to 89% predicted) in a double blind, randomized, crossover study after aerosolization of a single dose of UTP (5 mg/ml, 3.5 ml) or vehicle (0.12% saline, 3.5 ml). Clearance during cough (whole lung) was quantified during and after a series of controlled coughs by measuring the clearance of [99mTc]Fe2O3 particles via gamma camera scanning over 120 min. Safety parameters were recorded during and after drug delivery. Aerosolized UTP improved whole-lung clearance during cough as compared with vehicle (from 0 to 60 min: 0.40 ± 0.07%/min [UTP] versus 0.26 ± 0.04%/min [vehicle] [mean ± SEMI, p = 0.01), and from 0 to 120 min: 0.38 ± 0.05%/min [UTP] versus 0.25 ± 0.04%/min [vehicle], p = 0.02), Aerosolized UTP is safe, with no serious adverse effects. Whole-lung clearance during cough in patients with defective ciliary function is enhanced after inhalation of UTP

Germline mutations in an intermediate chain dynein cause primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous, autosomal recessive disorder caused by abnormal ciliary ultrastructure and function, characterized clinically by otosino-pulmonary disease. Mutations in an intermediate chain dynein (DNAI1: IC78) have recently been described in PCD patients, with outer dynein arm (ODA) defects. The aims of the current study were to test for novel DNAI1 mutations in 13 PCD patients with ODA defects (from 7 unrelated families) and to assess genotype/phenotype correlations in patients and family members. A previously reported mutation (219+3insT) was detected in three PCD patients from two families. The opposite allele had the novel missense mutation G1874C (W568S) in both affected individuals from one family, and a nonsense mutation G1875A (W568X) in an affected individual from another family. The tryptophan at position 568 is a highly conserved residue in the WD-repeat region, and a mutation is predicted to lead to abnormal folding of the protein and loss of function. None of these mutations were found in 32 other PCD patients with miscellaneous ciliary defects. Mutations in DNAI1 are causative for PCD with ODA defects, and are likely the genetic origin of clinical disease in some PCD patients with ultrastructural defects in the ODA

DNAH5 mutations are a common cause of primary ciliary dyskinesia with outer dynein arm defects

Rationale: Primary ciliary dyskinesia (PCD) is characterized by recurrent airway infections and randomization of left-right body asymmetry. To date, autosomal recessive mutations have only been identified in a small number of patients involving DNAI1 and DNAH5, which encode outer dynein arm components. Methods: We screened 109 white PCD families originating from Europe and North America for presence of DNAH5 mutations by haplotype analyses and/or sequencing. Results: Haplotype analyses excluded linkage in 26 families. In 30 PCD families, we identified 33 novel (12 nonsense, 8 frameshift, 5 splicing, and 8 missense mutations) and two known DNAH5 mutations. Weobserved clustering of mutationswithin five exons harboring 27 mutant alleles (52%) of the 52 detected mutant alleles. Interestingly, 6 (32%) of 19 PCD families with DNAH5 mutations from North America carry the novel founder mutation 10815delT. Electron microscopic analyses in 22 patients with PCD with mutations invariably detected outer dynein arm ciliary defects. High-resolution immunofluorescence imaging of respiratory epithelial cells from eight patients with DNAH5 mutations showed mislocalization of mutant DNAH5 and accumulation at the microtubule organizing centers. Mutant DNAH5 was absent throughout the ciliary axoneme in seven patients and remained detectable in the proximal ciliary axoneme in one patient carrying compound heterozygous splicing mutations at the 3′-end (IVS75-2A>T, IVS76+5G>A). In a preselected subpopulation with documented outer dynein arm defects (n = 47), DNAH5 mutations were identified in 53% of patients. Conclusions: DNAH5 is frequently mutated in patients with PCD exhibiting outer dynein arm defects and mutations cluster in five exons

Mutations in RSPH1 cause primary ciliary dyskinesia with a unique clinical and ciliary phenotype

Rationale: Primary ciliary dyskinesia (PCD) is a genetically heterogeneous recessive disorder of motile cilia, but the genetic cause is not defined for all patients with PCD. Objectives: To identify disease-causingmutations in novel genes, we performed exome sequencing, follow-up characterization, mutation scanning, and genotype-phenotype studies in patients with PCD. Methods: Whole-exome sequencing was performed using NimbleGen capture and Illumina HiSeq sequencing. Sanger-based sequencing was used for mutation scanning, validation, and segregation analysis. Measurements and Main Results: We performed exome sequencing on an affected sib-pair with normal ultrastructure in more than 85% of cilia. A homozygous splice-site mutation was detected in RSPH1 in both siblings; parents were carriers. Screening RSPH1 in 413 unrelated probands, including 325 with PCD and 88 with idiopathic bronchiectasis, revealed biallelic loss-of-function mutations in nine additional probands. Five affected siblings of probands in RSPH1 families harbored the familial mutations. The 16 individuals with RSPH1 mutations had some features of PCD; however, nasal nitric oxide levels were higher than in patients with PCD with other gene mutations (98.3 vs. 20.7 nl/min; P , 0.0003). Additionally, individuals with RSPH1 mutations had a lower prevalence (8 of 16) of neonatal respiratory distress, and later onset of daily wet cough than typical for PCD, and better lung function (FEV1), compared with 75 age- and sex-matched PCD cases (73.0 vs. 61.8, FEV1 % predicted; P = 0.043). Cilia from individuals with RSPH1 mutations had normal beat frequency (6.16Hz at 258C), but an abnormal, circular beat pattern. Conclusions: The milder clinical disease and higher nasal nitric oxide in individuals with biallelic mutations in RSPH1 provides evidence of a unique genotype-phenotype relationship in PCD, and suggests that mutations in RSPH1 may be associated with residual ciliary function

Airway mucus hyperconcentration in non–cystic fibrosis bronchiectasis

Rationale: Non–cystic fibrosis bronchiectasis is characterized by airway mucus accumulation and sputum production, but the role of mucus concentration in the pathogenesis of these abnormalities has not been characterized. Objectives: This study was designed to: 1) measure mucus concentration and biophysical properties of bronchiectasis mucus; 2) identify the secreted mucins contained in bronchiectasis mucus; 3) relate mucus properties to airway epithelial mucin RNA/protein expression; and 4) explore relationships between mucus hyperconcentration and disease severity. Methods: Sputum samples were collected from subjects with bronchiectasis, with and without chronic erythromycin administration, and healthy control subjects. Sputum percent solid concentrations, total and individual mucin concentrations, osmotic pressures, rheological properties, and inflammatory mediators were measured. Intracellular mucins were measured in endobronchial biopsies by immunohistochemistry and gene expression. MUC5B (mucin 5B) polymorphisms were identified by quantitative PCR. In a replication bronchiectasis cohort, spontaneously expectorated and hypertonic saline-induced sputa were collected, and mucus/mucin concentrations were measured. Measurements and Main Results: Bronchiectasis sputum exhibited increased percent solids, total and individual (MUC5B and MUC5AC) mucin concentrations, osmotic pressure, and elastic and viscous moduli compared with healthy sputum. Within subjects with bronchiectasis, sputum percent solids correlated inversely with FEV1 and positively with bronchiectasis extent, as measured by high-resolution computed tomography, and inflammatory mediators. No difference was detected in MUC5B rs35705950 SNP allele frequency between bronchiectasis and healthy individuals. Hypertonic saline inhalation acutely reduced non–cystic fibrosis bronchiectasis mucus concentration by 5%. Conclusions: Hyperconcentrated airway mucus is characteristic of subjects with bronchiectasis, likely contributes to disease pathophysiology, and may be a target for pharmacotherapy

Ability to Transmit Sugarcane Mosaic Virus and Seasonal Phenology of Some Aphid Species (Hemiptera: Aphididae) in the Isis and Bundaberg Districts of Queensland

Rhopalosiphum maidis (Fitch), Aphis gossypii Glover and Myzus persicae (Sultzer) transmitted the Australian sugarcane strain of sugarcane mosaic virus (SCMV‐SC) in a non‐persistent manner, whereas Melanaphis sacchari (Zehntner), Hysteroneura setariae (Thomas), Hyperomyzus lactucae (L.) and Aphis nerii Boyer de Fonscolombe did not transmit the virus. Calculated transmission rate per aphid was higher (12–16%) when sweetcorn was the source of SCMV‐SC than when sugarcane was the source (2–5%). M. sacchari (a non‐vector) and A. gossypii (a vector) were the most prevalent aphids caught on sticky yellow traps in the Isis and Bundaberg districts in 1989–91. Three vector species, A craccivora Koch, A. gossypii and R. maidis, were trapped mainly in spring, summer and autumn, and a fourth vector species, R. padi (L.) was trapped only in winter. Since vector species were active during all seasons, there is always potential for transmission of SCMV‐SC if host, virus and environmental factors are favourable. Copyrigh