Immotile cilia syndrome (ICS), also known as Primary Ciliary Dyskinesia, is a genetic disorder which is generally inherited in an autosomal recessive fashion. The incidence appears to be about 1/30,000. ICS affects ciliary movement, ranging from dysmotility or even complete immotility of spermatozoa as well as cilia in ciliated epithelia. This primary defect in ciliary function leads to recurrent pulmonary and upper respiratory tract infections, resulting often in bronchiectasis. Hearing problems, situs inversus and male infertility are associated symptoms. Most clinical manifestations begin in early childhood. Diagnostic tests, based on clinical symptoms, mucociliary clearance and ultrastructure, do not always give clear and satisfactory results. Treatment, which is currently purely symptomatic, involves dealing with complications in the upper and lower respiratory tracts. None of the gene(s) involved has been identified, although genetic heterogeneity is suspected on the basis of the complex architecture of cilia.

Given the rarity of familial cases of ICS, a multinational collaboration is clearly necessary, since only this will allow the identification of a sufficiently large group of patients to overcome the problems associated with the genetic heterogeneity likely to be present. Furthermore, only the envisaged type of project will bring clinicians and scientists with complementary fields of expertise together. The partners of this project are convinced that improvement of diagnosis and eventually treatment of the disorder are crucially dependent on progress in identifying the genetic defects responsible. Finally, the proposed research is not only likely to be of value to patients and their families, but will also shed light on the large number of ciliary gene products and their involvement in determining spatial relationships among cells and organs in early human embryological development.