Kartagener syndrome is an autosomal recessive condition. This means that in order to have the condition, an individual needs to inherit two copies of the gene for the condition, one from each parent. Individuals who carry only one gene for an autosomal recessive syndrome are called heterozygotes. Heterozygotes for Kartagener syndrome have normal ciliary function and do not have any clinical features of the condition. If two carriers of Kartagener syndrome have children, there is a 25% chance, with each pregnancy, for having a child with Kartagener syndrome.
The components that form the cilium contain several hundred different proteins. Each is coded for by different DNA sequences, potentially on different chromosomes. A defect in any of these codes could produce an abnormal or missing protein that is a building block for the cilium and thus could cause abnormal ciliary structure and movement, resulting in Kartagener syndrome.
When the same condition can be caused by different genetic abnormalities, this is known as genetic heterogeneity. In fact, several different defects in cilia have been seen in association with Kartagener syndrome, including; overly long cilia, overly short cilia, absent cilia and randomly oriented cilia, suggesting genetic heterogeneity. Studies have suggested that the most common defect of cilia in Kartagener syndrome is the lack of dynein arms. There have been rare cases in which individuals have Kartagener syndrome, yet have no detectable abnormality of the cilia, even though the ciliary function is abnormal. Results of one study involving a genome-wide linkage search performed on 31 families, with multiple individuals affected with either PCD or Kartagener syndrome, strongly suggested extensive heterogeneity. Potential regions involving genes responsible for PCD or Kartagener syndrome were localized on chromosomes 3, 4, 5, 7, 8, 10, 11, 13, 15, 16, 17 and 19.
Renee A. Laux MS, Thomson Gale, Gale, Detroit,