Kartagener syndrome Health Article

Definition

Kartagener (pronounced KART-agayner) syndrome refers to a condition that involves difficulty with clearing mucus secretions from the respiratory tract, male infertility, and situs inversus. The defining characteristic of this syndrome is the situs inversus, which is a reversal of abdominal and thoracic organs.

Description

This syndrome is named after Kartagener, a physician from Switzerland. In the 1930's, Kartagener and a colleague described a familial form of bronchiectasis with situs inversus and nasal polyps. This came to be known as Kartagener syndrome. Kartagener syndrome is also known as the Siewert syndrome, after another physician, Siewert, who described the syndrome in the early 1900's.

Individuals who have Kartagener syndrome form a subset of the disorder called primary ciliary dyskinesia. Originally, primary ciliary dyskinesia was known as immotile cilia syndrome. The name, immotile cilia syndrome, is no longer used since the discovery that the cilia are actually not immotile, but rather, abnormal in movement. Individuals who have Kartagener syndrome, basically have primary ciliary dyskinesia, plus partial or complete situs inversus. The situs inversus is what sets Kartagener syndrome apart from primary ciliary dyskinesia.

Kartagener syndrome is caused by abnormalities of the cilia that line the respiratory tract and also form the flagella of sperm. Cilia are tiny hair-like structures that contain a bundle of small parallel tubes that form a central core. This core is called the axoneme. Ciliary movement is accomplished by the bending of the axoneme. One of the most important associated structures that enable ciliary movement to occur are sets of tiny arms that project from each tubule. These tiny arms are called dynein arms.

Cilia line the cells of the lungs, nose and sinuses. Before reaching the lungs, air travels through the airway where it is moistened and filtered. The nasal passages and airway are lined with mucus membranes. The mucus covering the mucus membrane traps dirt and other foreign particles that have been breathed in. The cilia, lining the membranes, beat in a wavelike manner moving the layer of mucus and carrying away the dirt and debris that has been trapped. This mucus can then be coughed out or swallowed into the stomach.

In Kartagener syndrome, the cilia do not move, move very little, or move abnormally. Because the cilia do not function properly, the mucus is not cleared from the respiratory tract, which leads to sinus infection (sinusitis) and chronic changes of the lung (bronchiectasis), which make it difficult to exhale. Mucus clearance from the middle ear can also be affected and over time can lead to hearing loss.

The male infertility in Kartagener syndrome is also caused by abnormal cilia movement. One spermatozoon consists of a head, midpiece, and a tail or flagellum. The tail of a spermatozoon is a long flagellum consisting of a central axoneme. This axoneme enables the movement of the flagellum so that the spermatozoon can propel its way to the fallopian tube and burrow through the egg coat to fertilize the egg. In Kartagener syndrome, these cilia are either immotile, or are not able to move normally to complete the journey to the fallopian tubes, nor may they be able to burrow through the egg coat. This results in male infertility.

As stated above, situs inversus is what sets Kartagener syndrome apart from primary ciliary dyskinesia. Complete situs inversus involves reversal of both the abdominal and thoracic organs so that they form a mirror image of normal. In partial situs inversus, the thoracic organs may be reversed, while the abdominal organs are normally positioned, or vice versa. Approximately one in 10,000 adults have situs inversus. Only about 20% of individuals who have complete situs inversus are diagnosed to have Kartagener syndrome. Of those with complete situs inversus who are diagnosed to have Kartagener syndrome, there is only a small risk for associated cardiac defects. Partial situs inversus may occur in individuals who have Kartagener syndrome as well. Partial situs inversus has a higher association with other abnormalities, including polysplenia or asplenia (extra or absent spleen) and cardiac defects.

One theory behind the association of situs inversus with the underlying cause of Kartagener syndrome is that the lack of ciliary movement in the developing embryo may result in incorrect organ rotation in approximately 50% of affected individuals. In fact, 50% of patients with PCD will have situs inversus and thus be diagnosed to have Kartagener syndrome. However, this is a theory supported only by some researchers.