Primary ciliary dyskinesia-causing mutations in Amish and Mennonite communities.

OBJECTIVE: To determine whether individuals with primary ciliary dyskinesia (PCD) from unrelated Amish and Mennonite families harbor a single and unique founder mutation. STUDY DESIGN: Subjects from Amish and Mennonite communities in several states were enrolled in the study. All subjects were clinically characterized, and nasal nitric oxide levels were measured. Nasal epithelial scrapings were collected from several subjects for ciliary ultrastructural analyses. DNA was isolated from patients with PCD and their unaffected first- and second-degree relatives. Genome-wide homozygosity mapping, linkage analyses, targeted mutation analyses, and exome sequencing were performed. RESULTS: All subjects from Old-Order Amish communities from Pennsylvania were homozygous for a nonsense mutant DNAH5 allele, c.4348C>T (p.Q1450X). Two affected siblings from an unrelated Mennonite family in Arkansas were homozygous for the same nonsense DNAH5 mutation. Children with PCD from an Amish family from Wisconsin had biallelic DNAH5 mutations, c.4348C>T (p.Q1450X) and c.10815delT (p.P3606HfsX23), and mutations in other genes associated with PCD were also identified in this community. CONCLUSION: The Amish and Mennonite subjects from geographically dispersed and socially isolated communities had the same founder DNAH5 mutation, owing to the common heritage of these populations. However, disease-causing mutations in other PCD-associated genes were also found in affected individuals in these communities, illustrating the genetic heterogeneity in this consanguineous population.

Primary ciliary dyskinesia in Amish communities.

Primary ciliary dyskinesia is an autosomal recessive multigenic disease that results in impaired mucociliary clearance. We have diagnosed 9 subjects with primary ciliary dyskinesia from geographically dispersed Amish communities, on the basis of clinical characteristics and ciliary ultrastructural defects. Despite consanguinity, affected individuals had evidence of genetic heterogeneity.

Primary ciliary dyskinesia: recent advances in pathogenesis, diagnosis and treatment.

Primary ciliary dyskinesia is a genetic disorder causing dysfunctional motility of cilia and impaired mucociliary clearance, resulting in a myriad of clinical manifestations including recurrent sinopulmonary disease, laterality defects and infertility. The heterogenous clinical presentation of primary ciliary dyskinesia and the limitations of transmission electron microscopy to assess ultrastructural defects within the cilium often delay diagnosis. Recent advances in the understanding of the basic biology and function of the cilium have led to potential diagnostic alternatives, including ciliary beat analysis and nasal nitric oxide measurements. Moreover, the identification of disease-causing mutations could lead to the development of comprehensive genetic testing that may overcome many of the current diagnostic limitations. Although the clinical manifestations of primary ciliary dyskinesia have been recognised for over a century, there are few studies examining treatments and standards of care have yet to be established. Multicentre collaborative efforts have been established in North America and Europe, which should help to develop standardised approaches to the diagnosis and treatment of primary ciliary dyskinesia.