Mutations of DNAH11 in patients with primary ciliary dyskinesia with normal ciliary ultrastructure
ABSTRACT Primary ciliary dyskinesia (PCD) is an autosomal recessive, genetically heterogeneous disorder characterised by oto-sino-pulmonary disease and situs abnormalities (Kartagener syndrome) due to abnormal structure and/or function of cilia. Most patients currently recognised to have PCD have ultrastructural defects of cilia; however, some patients have clinical manifestations of PCD and low levels of nasal nitric oxide, but normal ultrastructure, including a few patients with biallelic mutations in dynein axonemal heavy chain 11 (DNAH11).
To test further for mutant DNAH11 as a cause of PCD, DNAH11 was sequenced in patients with a PCD clinical phenotype, but no known genetic aetiology.
82 exons and intron/exon junctions in DNAH11 were sequenced in 163 unrelated patients with a clinical phenotype of PCD, including those with normal ciliary ultrastructure (n=58), defects in outer and/or inner dynein arms (n=76), radial spoke/central pair defects (n=6), and 23 without definitive ultrastructural results, but who had situs inversus (n=17), or bronchiectasis and/or low nasal nitric oxide (n=6). Additionally, DNAH11 was sequenced in 13 subjects with isolated situs abnormalities to see if mutant DNAH11 could cause situs defects without respiratory disease.
Of the 58 unrelated patients with PCD with normal ultrastructure, 13 (22%) had two (biallelic) mutations in DNAH11; and two patients without ultrastructural analysis had biallelic mutations. All mutations were novel and private. None of the patients with dynein arm or radial spoke/central pair defects, or isolated situs abnormalities, had mutations in DNAH11. Of the 35 identified mutant alleles, 24 (69%) were nonsense, insertion/deletion or loss-of-function splice-site mutations.
Mutations in DNAH11 are a common cause of PCD in patients without ciliary ultrastructural defects; thus, genetic analysis can be used to ascertain the diagnosis of PCD in this challenging group of patients.
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ABSTRACT: Introduction: Primary ciliary dyskinesia (PCD) is a genetically heterogeneous recessive disorder resulting in chronic oto-sino-pulmonary disease. While PCD is estimated to occur in 1 in 20,000 individuals, fewer than 1000 patients in the USA have a well-established diagnosis.Areas covered: We provide an overview of the clinical manifestations of PCD, describe the evolution of diagnostic methods and critique the literature on management of PCD.Expert opinion: Although interest in clinical studies in non-cystic fibrosis bronchiectasis has increased in recent years, some of whom enroll patients with PCD, the literature regarding therapy for PCD as a distinct entity is lacking, as the numbers are small, and there have been no subanalyses published. However, with improved screening and diagnostic methods, the development of clinical and research consortiums, and actively enrolling registries of PCD patients, the environment is conducive to perform longitudinal studies of disease course and therapeutic studies to alter that course.11/2014; 3(1). DOI:10.1517/21678707.2015.989212
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ABSTRACT: Rationale: The relationship between clinical phenotype of childhood primary ciliary dyskinesia (PCD) and ultrastructural defects and genotype is poorly defined. Objectives: To delineate clinical features of childhood PCD and their associations with ultrastructural defects and genotype. Methods and Measurements: 118 participants <19 years old with PCD were evaluated prospectively at 6 centers in North America using standardized procedures for diagnostic testing, spirometry, chest computed tomography, respiratory cultures, and clinical phenotyping. Main Results: Clinical features included neonatal respiratory distress (82%), chronic cough (99%), and chronic nasal congestion (97%). There were no differences in clinical features or respiratory pathogens in subjects with outer dynein arm (ODA) defects (ODA alone, n=54) and ODA plus inner dynein arm (IDA) defects (ODA+IDA; n=18) versus subjects with IDA and central apparatus defects with microtubular disorganization (IDA/CA/MTD; n=40). Median FEV1 was worse in the IDA/CA/MTD group (72% predicted) versus the combined ODA groups (92% predicted; p=0.003). Median BMI was lower in the IDA/CA/MTD group (46th percentile) versus the ODA groups (70th percentile; p=0.003). For all 118 subjects, median number of lobes with bronchiectasis was 3 and alveolar consolidation was 2. However, the 5-11 year old IDA/CA/MTD group had more lobes of bronchiectasis (median= 5, p=0.0008) and consolidation (median=3, p=0.0001) compared to the ODA groups (median=3 and 2, respectively). Similar findings were observed when limited to participants with biallelic mutations. Conclusions: Lung disease was heterogeneous across all ultrastructural and genotype groups, but worse in those with IDA/CA/MTD ultrastructural defects, most of whom had biallelic mutations in CCDC39 or CCDC40.American Journal of Respiratory and Critical Care Medicine 12/2014; DOI:10.1164/rccm.201409-1672OC · 11.99 Impact Factor
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ABSTRACT: Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disorder with defective structure and/or function of motile cilia/flagella, causing chronic upper and lower respiratory tract infections, fertility problems, and disorders of organ laterality. Diagnosing PCD requires a combined approach utilizing characteristic phenotypes and complementary methods for detection of defects of ciliary function and ultrastructure, measurement of nasal nitric oxide and genetic testing. Currently, biallelic mutations in 31 different genes have been linked to PCD allowing a genetic diagnosis in approximately ~ 60% of cases. Management includes surveillance of pulmonary function, imaging, and microbiology of upper and lower airways in addition to daily airway clearance and prompt antibiotic treatment of infections. Early referral to specialized centers that use a multidisciplinary approach is likely to improve outcomes. Currently, evidence-based knowledge on PCD care is missing let alone management guidelines. Research and clinical investigators, supported by European and North American patient support groups, have joined forces under the name of BESTCILIA, a European Commission funded consortium dedicated to improve PCD care and knowledge. Core programs of this network include the establishment of an international PCD registry, the generation of disease specific PCD quality of life questionnaires, and the first randomized controlled trial in PCD.01/2015; 4(1):2. DOI:10.1186/s13630-014-0011-8