Mutations ofDNAH11in patients with primary ciliary dyskinesia with normal ciliary ultrastructure

Abstract

Rationale Primary ciliary dyskinesia (PCD) is an autosomal recessive, genetically heterogeneous disorder characterized by oto-sino-pulmonary disease and situs abnormalities (Kartagener syndrome) due to abnormal structure and/or function of cilia. Most patients currently recognized 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 DNAH11. Objectives In order to test further for mutant DNAH11 as a cause of PCD, we sequenced DNAH11 in patients with a PCD clinical phenotype, but no known genetic etiology. Methods We sequenced 82 exons and intron/exon junctions in DNAH11 in 163 unrelated patients with a clinical phenotype of PCD, including those with normal ciliary ultrastructure (n=58), defects in outer ± 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, we sequenced DNAH11 in 13 patients with isolated situs abnormalities to see if mutant DNAH11 could cause situs defects without respiratory disease. Results Of the 58 unrelated PCD patients with normal ultrastructure, 13 (22%) had two (biallelic) mutations in DNAH11; plus, 2 PCD 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 Ioss-of-function splice-site mutations. Conclusions 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.

Standardizing Nasal Nitric Oxide Measurement as a Test for Primary Ciliary Dyskinesia

“…For nNO validation studies at six (non-UNC) sites, PCD was confirmed by PCD-specific ciliary EM defects and, by the presence of biallelic mutations in PCD genes (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31). Informed consent was obtained at the University of North Carolina at Chapel Hill and collaborating institutions under the auspices of Committees on the Protection of the Rights of Human Subjects.…”

“…An isolated IDA defect was not diagnostic, as this can be nonspecific (19). PCD was confirmed by identification of biallelic DNAH11 mutations in patients with normal ultrastructure (20). Data were entered in a web-based Data Management Coordinating Center (Director, J. Krischer), including laterality defects and clinical features.…”

Diagnostic Methods in Primary Ciliary Dyskinesia

“…For example, defects of nexin link components [63], central pair components [64], ciliary biogenesis defects [14] and defects caused by DNAH11 [65,66], usually cannot be visualized by classic TEM. Thus, normal ultrastructure cannot rule out PCD.…”

“…Mutations in these genes cause structural and functional ODA defects and consequently ciliary immotility [47,48]. However, in DNAH11, TEM is normal and thus not informative [65,66,75].…”

Clinical care for primary ciliary dyskinesia: current challenges and future directions

“…TEM was once the "gold standard" for PCD diagnosis. However, it is now known that 15-20% of PCD cases have disease-causative mutations but normal ultrastructure by TEM [30,39,[41][42][43]. A quantitative approach to cilia evaluation is recommended, but there is no agreement on the minimal number of cilia scored or on the terminology used for ultrastructural defects.…”