Primary ciliary dyskinesia (PCD), also known as immotile ciliary syndrome, is a rare autosomal recessive genetic disorder caused by a defect in the action of cilia lining the respiratory tract. Specifically, it is a defect in a gene coding for left-right dynein (lrd), a key structural protein in cilia.Chodhari R, Mitchison HM, Meeks M. Cilia, primary ciliary dyskinesia and molecular genetics. Paediatr Respir Rev. 2004 Mar;5(1):69-76. When accompanied by the triad of situs inversus, chronic sinusitis, and bronchiectasis, it is known as Kartagener syndrome. Use of immotile ciliary syndrome is no longer favoured, as sperm in affected men often have some motility - the term was coined in the mistaken belief that they had none.

The dysfunction of the cilia begins during the embryologic phase of development. Since the cilia aid in the movement of growth factors resulting in the normal rotation of the internal organs during early embryological development, 50% of these individuals will develop situs inversus, as the laterality of the viscera is determined by chance.

The main consequence of impaired ciliary function is reduced or absent mucus clearance in the lungs, and susceptibility to chronic, recurrent respiratory infections, including sinusitis, bronchitis, pneumonia, and otitis media. The disease typically affects children up to 18 years of age, but the defect associated with it has a variable clinical impact on disease progression in adults as well. Many patients experience hearing loss and a poor sense of smell, and infertility is common. Clinical progression of the disease is variable with lung transplantation required in severe cases. For most patients, aggressive measures to enhance clearance of mucus, prevent respiratory infections, and treat bacterial superinfections are recommended. Although the true incidence of the disease is unknown, it is estimated to be 1 in 32,000 or higherCeccaldi PF, Carre-Pigeon F, Youinou Y, Delepine B, Bryckaert PE, Harika G, Quereux C, Gaillard D. syndrome and infertility: observation, diagnosis and treatment J Gynecol Obstet Biol Reprod (Paris). 2004 May;33(3):192-4..

The classical triad was first described by A. K. Zivert in 1904 while Kartagener published his first report in 1933.

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