Burdine reasoned that zebrafish embryos with the mutated version of the gene also should possess some sort of defect in the cilia themselves. However, views of the cilia in zebrafish embryos through normal lab microscopes showed nothing beyond the ordinary.
For a closer look, Burdine employed a special transmission electron microscope. She examined the microscopic cilia in the zebrafish with the mutation in CCDC40 and compared those images with zebrafish with the normal gene. The cilia in the zebrafish with the mutations "were disrupted in their structure in a way I had never seen before," Burdine said.
She sent the images to Omran, who was treating people with a disorder known as primary ciliary dyskinesia or PCD. These patients suffer from a defect in the action of the cilia lining the respiratory tract. Normally, cilia beat rhythmically, moving mucus toward the throat. If cilia are impaired, however, they cannot reduce or remove mucus from the lungs, leaving people with the disorder susceptible to chronic recurrent respiratory infections, including bronchitis and pneumonia. Since motile cilia also are required for proper left-right patterning, these patients also often have defects in organ positioning.
Of the 26 patients with similar cilia structural defects tested by Omran, some 17 were found to have mutated versions of the gene CCDC40. In addition to the respiratory ciliary disorder, the patients also suffered from congenital heart defects. This finding provided evidence of a link between the cilia-induced respiratory disorder and the heart problems.
By knowing the gene and the properties conferred by its mutated version, scientists may be able to better treat those with the mutant gene and its accompanying respiratory disorders. Researc
|Contact: Kitta MacPherson|