New DNAH11 mutations in primary ciliary dyskinesia with normal axonemal ultrastructure

Abstract

To the Editors: In primary ciliary dyskinesia (PCD; Mendelian Inheritance in Man database #242650), a rare genetic disorder, the dysfunctional motility of cilia and impaired mucociliary clearance result in a myriad of clinical manifestations including recurrent infections of the respiratory tract, eventually causing lung damage, such as bronchiectasis, laterality defects and male infertility 1. The heterogeneous clinical presentation of PCD and the limitations of transmission electron microscopy (TEM) to assess ultrastructural defects within the cilium may delay the diagnosis 2. Ciliary beat frequency and pattern analyses and nasal nitric oxide (nNO) measurements are helpful 1, 3, 4, but only ciliogenesis in cultured cells has been reported as decisive for the diagnosis of the atypical PCD phenotype with normal axonemal ultrastructure 1, 5. Under these conditions, the identification of disease-causing mutations could overcome the current diagnostic limitations of TEM and improve our understanding of the biology and function of the cilium 2, 6, 7. For these reasons, we have assessed whether an analysis of the DNAH11 gene, in which some nonsense mutations have been reported to be associated with a normal axonemal ultrastructure but with an abnormal nonflexible beating pattern, reduced cilium bending capacity and a hyperkinetic beat 7, could be used to identify new mutations in three atypical PCD patients and thus be used in the diagnostic work-up of these most difficult cases. We observed three patients (A and B, sister and brother; and C, male), at the ages of 15 yrs and 5 months, 9 yrs and 4 months, and 8 yrs, respectively. The two siblings presented situs inversus. Both patients had chronic respiratory symptoms which required repeated treatment with antibiotics. Patient A also had neonatal purulent rhinitis with frequent relapses, chronic rhinosinusitis and otitis …