Clinical features and management of children with primary ciliary dyskinesia in England

Objective In England, the National Health Service commissioned a National Management Service for children with primary ciliary dyskinesia (PCD). The aims of this study were to describe the health of children seen in this Service and compare lung function to children with cystic fibrosis (CF). Design Multi-centre service evaluation of the English National Management PCD Service. Setting Four nationally commissioned PCD centres in England. Patients 333 children with PCD reviewed in the Service in 2015; lung function data were also compared to 2970 children with CF. Results Median age at diagnosis for PCD was 2.6 years, significantly lower in children with situs inversus (1.0 vs 6.0 years, p<0.0001). Compared with national data from the CF Registry, mean (SD) %predicted FEV1 76.8% in PCD (n=240) and 85.0% in CF, and FEV1 was lower in children with PCD up to the age of 15 years. Approximately half of children had some hearing impairment, with 26% requiring hearing aids. Children with a lower BMI had lower FEV1 (p<0.001). One third of children had positive respiratory cultures at review, 54% of these grew Haemophilus influenzae. Conclusions We provide evidence that children with PCD in England have worse lung function than those with CF. Nutritional status should be considered in PCD management, as those with a lower BMI have significantly lower FEV1. Hearing impairment is common but seems to improve with age. Well designed and powered randomised controlled trials on management of PCD are needed to inform best clinical practice

Risk factors for situs defects and congenital heart disease in primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is associated with abnormal organ positioning (situs) and congenital heart disease (CHD). This study investigated genotype–phenotype associations in PCD to facilitate risk predictions for cardiac and laterality defects. This retrospective cohort study of 389 UK patients with PCD found 51% had abnormal situs and 25% had CHD and/or laterality defects other than situs inversus totalis. Patients with biallelic mutations in a subset of nine PCD genes had normal situs. Patients with consanguineous parents had higher odds of situs abnormalities than patients with non-consanguineous parents. Patients with abnormal situs had higher odds of CHD and/or laterality defects

Clinical utility of NGS diagnosis and disease stratification in a multiethnic primary ciliary dyskinesia cohort

Background Primary ciliary dyskinesia (PCD), a genetically heterogeneous condition enriched in some consanguineous populations, results from recessive mutations affecting cilia biogenesis and motility. Currently, diagnosis requires multiple expert tests.Methods The diagnostic utility of multigene panel next-generation sequencing (NGS) was evaluated in 161 unrelated families from multiple population ancestries.Results Most (82%) families had affected individuals with biallelic or hemizygous (75%) or single (7%) pathogenic causal alleles in known PCD genes. Loss-of-function alleles dominate (73% frameshift, stop-gain, splice site), most (58%) being homozygous, even in non-consanguineous families. Although 57% (88) of the total 155 diagnostic disease variants were novel, recurrent mutations and mutated genes were detected. These differed markedly between white European (52% of families carry DNAH5 or DNAH11 mutations), Arab (42% of families carry CCDC39 or CCDC40 mutations) and South Asian (single LRRC6 or CCDC103 mutations carried in 36% of families) patients, revealing a striking genetic stratification according to population of origin in PCD. Genetics facilitated successful diagnosis of 81% of families with normal or inconclusive ultrastructure and 67% missing prior ultrastructure results.Conclusions This study shows the added value of high-throughput targeted NGS in expediting PCD diagnosis. Therefore, there is potential significant patient benefit in wider and/or earlier implementation of genetic screening

Effect Of Catecholamines And Inhaled Drugs On The Growth And Virulence Of Bacterial Respiratory Pathogens

Background: Pseudomonas aeruginosa (P. aeruginosa) and Burkholderia cenocepacia (B. cenocepacia), a member of the Burkholderia cepacia complex (Bcc) are common biofilm forming pathogens in Cystic Fibrosis (CF) patients. Bcc contributes to mortality in CF lung transplantees. Drugs such as catecholamines and salbutamol are known to interact with bacteria in general. In CF and post transplanted patients, both these drugs are commonly used and can possibly interact with P. aeruginosa and B. cenocepacia, and enhance their virulence. Aim: 1. To evaluate whether catecholamines affect the growth and virulence of B, cenocepacia. 2. To evaluate whether Salbutamol affects the growth and virulence of B. cenocepacia and P. aeruginosa. 3. To evaluate whether there was any interaction of Burkholderia with the ciliary epithelium and if the drugs catecholmaines and salbutamol affected this. Methods: In vitro methods for growth, attachment and biofilm formation were carried out for B. cenocepacia with drugs, catecholamine and salbutamol, and for P. aeruginosa with salbutamol. To give a clinical context, biofilm formation on endotracheal tubes and ex vivo studies on healthy and CF airway epithelial cultures with and without supplemental drugs were carried out. Results: B. cenocepacia were found to be catecholamine responsive organisms. Catecholamines increased the growth and biofilm formation of B. cenocepacia. Salbutamol did not influence the growth of either B. cenocepacia or P. aeruginosa, but increased the cell to cell aggregation. On endotracheal tubes both drugs enhance the formation of mature biofilms. B. cenocepacia infection on airway cultures did not affect ciliary beat frequency but attached to ciliary tips by five hours and was able to form mature biofilms and this was enhanced in presence of catecholamines and in CF epithelial cultures. Summary: Catecholamines increase the growth, attachment and biofilm forming ability of B. cenocepacia. Salbutamol, a commonly used respiratory drug has an influence on the cell to cell aggregation for bacteria. B. cenocepacia produce biofilm within 5 hours after infection of the airway epithelium especially in CF epithelial cultures and more so with catecholamines. This observation is relevant to CF patients to guide clinical practice and detect mechanism of bacterial infection which may offer a therapeutic target for CF patients

Ciliopathy patient variants reveal organelle-specific functions for TUBB4B in axonemal microtubules

Tubulin, one of the most abundant cytoskeletal building blocks, has numerous isotypes in metazoans encoded by different conserved genes. Whether these distinct isotypes form cell type– and context-specific microtubule structures is poorly understood. Based on a cohort of 12 patients with primary ciliary dyskinesia as well as mouse mutants, we identified and characterized variants in the TUBB4B isotype that specifically perturbed centriole and cilium biogenesis. Distinct TUBB4B variants differentially affected microtubule dynamics and cilia formation in a dominant-negative manner. Structure-function studies revealed that different TUBB4B variants disrupted distinct tubulin interfaces, thereby enabling stratification of patients into three classes of ciliopathic diseases. These findings show that specific tubulin isotypes have distinct and nonredundant subcellular functions and establish a link between tubulinopathies and ciliopathies.</p

Ciliopathy patient variants reveal organelle-specific functions for TUBB4B in axonemal microtubules

Tubulin, one of the most abundant cytoskeletal building blocks, has numerous isotypes in metazoans encoded by different conserved genes. Whether these distinct isotypes form cell type– and context-specific microtubule structures is poorly understood. Based on a cohort of 12 patients with primary ciliary dyskinesia as well as mouse mutants, we identified and characterized variants in the TUBB4B isotype that specifically perturbed centriole and cilium biogenesis. Distinct TUBB4B variants differentially affected microtubule dynamics and cilia formation in a dominant-negative manner. Structure-function studies revealed that different TUBB4B variants disrupted distinct tubulin interfaces, thereby enabling stratification of patients into three classes of ciliopathic diseases. These findings show that specific tubulin isotypes have distinct and nonredundant subcellular functions and establish a link between tubulinopathies and ciliopathies.</p