Nearly 60 years after Dorothy left gray Kansas for the vibrant land of Oz, wizards of a different sort have concocted a powerful new way to visualize the full set of human chromosomes in a rainbow of colors. The new technique, called "spectral karyotyping," translates computer-gathered light waves into a full-color palette and assigns each chromosome its own distinct hue. With all 23 pairs of human chromosomes identified by a different color, scientists can more easily examine the entire group of chromosomes for changes that could lead to disease, such as missing or extra pieces, or parts from different chromosomes that have swapped places. The technique could prove to be extremely valuable in diagnosis of disease based on chromosome alterations.
"The value of chromosome examination in understanding the changes that take place during disease progression could be greatly enhanced if we could study the entire genome at once, and clearly distinguish genetic material belonging to one chromosome from that of another," said NCHGR scientist Thomas Ried, M.D., who led the group that developed the technique. They report their findings in the July 26 issue of the journal Science*.
The power of the current diagnostic techniques is limited in examining whole chromosome sets, called karyotypes, for changes because the methods rely on chemical stains that reveal only shades of gray. Pieces exchanged from one chromosome to another--a process called "translocation" that is often associated with disease--cannot easily be detected. And in diseased cells containing several badly distorted chromosomes, tracking the multiplication or exchange of genetic material is often impossible with conventional black-and-white banding.
Chromosome banding was first developed in the early 1970s, when it was observed that each human chromosome portrayed a characteristic pattern of bands when exposed to chemical stains. This allowed researchers to identify and sort
Contact: David Brand
University of Washington