Ciliary dysmorphology and dysfunction - primary or acquired?

Article Abstract:

Around the turn of the century A. Siewert observed that bronchiectasis was common among patients with situs inversus, a condition in which the normal left-right pattern of the internal organs is reversed. Bronchiectasis is a condition of dilated bronchi causing fetid breath and coughing up of purulent mucus. Only many years later was it observed that patients with situs inversus also have abnormal movement of the cilia. Since cilia are responsible for constantly removing dust, fine particles, and bacteria out of the respiratory tract, any abnormality in their movement is likely to result in recurrent respiratory disease. Why patients with inverted internal organs should also have abnormal cilia is uncertain, but it has been suggested that cilia help to move the organs into their proper orientation during embryonic development. If this were true, then we might expect that without functioning cilia, the orientation of the internal organs would be random, reversed about half the time and correct about half the time among patients with immotile cilia. Indeed, this is exactly what is observed; about half of all patients with defects of ciliary motion have situs inversus. The syndrome associated with defective ciliary motion is now referred to as primary ciliary dyskinesia. This condition, which is genetic, ranks among the 'big three' of inherited respiratory disease, along with cystic fibrosis and alpha-1-antitrypsin deficiency (which causes emphysema in many patients). In the December 13, 1990 issue of The New England Journal of Medicine, researchers report a novel case that they believe to be an example of a new form of primary ciliary dyskinesia. In this case, the cilia of a boy showed normal motility. However, the cilia seemed to be oriented randomly, rather than uniformly, as is the case with most cilia. The disorganization of the cilia, each one of which is beating properly on its own, was believed to be the source of the respiratory symptoms of the patient. However, before this case may be considered an example of primary ciliary dyskinesia, alternative hypotheses must be ruled out. Environmental conditions or a history of respiratory disease should be explored as possible causes for the disruption of the normal pattern of cilia before a patient's condition can be considered genetic. (Consumer Summary produced by Reliance Medical Information, Inc.)

Physiological aspects, editorial

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Random ciliary orientation: a cause of respiratory tract disease

Article Abstract:

In the normal lining of the airways, countless numbers of microscopically small hair-like cilia beat rhythmically to remove dust, microorganisms, and other tiny particles. In the 1970s, researchers found that some patients with frequent respiratory tract infections and disease suffer from a defect in the movement of these cilia. Investigation using the electron microscope revealed a defect in the protein structure within the cilia that serves as the molecular motor providing normal motion. These observations led to the adoption of the term 'primary ciliary dyskinesia' to describe the syndrome. The ciliary beat frequency may be determined by the microscopic examination of a small piece of living nasal tissue. The normal function of the cilia may be observed by placing a tiny crystal of saccharin on the mucosal lining deep within the nose. In a healthy person, the motion of the cilia will bring saccharin molecules into the mouth, and the subject will be able to identify a strong, sweet taste in about 30 minutes. Recently, an 11-year-old boy with a history of respiratory problems suggestive of primary ciliary dyskinesia was examined. Testing revealed that the patient had an almost normal beat frequency, but clearance of saccharin from the nasal mucosa was abnormally slow. This unusual combination led to further investigation of the cilia in this patient. Careful examination of electron micrographs showed that, although the cilia were normal in number, they were oriented randomly, in marked contrast to the uniform orientation seen among normal cilia. The individual cilia were apparently beating normally, but were not functioning in unison. This observation provides identification of another type of defect that can inhibit the normal function of cilia and cause primary ciliary dyskinesia. (Consumer Summary produced by Reliance Medical Information, Inc.)

Causes of

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X-linked Wiskott-Aldrich syndrome in a girl

Article Abstract:

The case of an eight-year-old girl illustrates how an X-linked genetic disorder can affect girls. Normally, X-linked disorders only affect boys because girls have two X chromosomes whereas boys only have one. The girl was hospitalized at the age of two months because her blood platelet counts were low. She experienced repeated infections and bleeding due to low platelet counts. Her symptoms led to a diagnosis of Wiskott-Aldrich syndrome, a type of immunodeficiency that normally affects boys.

Diseases, Wiskott-Aldrich syndrome, Girls

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