Term of the Week - FISH Analysis

Do you ever wonder how scientists think up names for things - for example, FISH testing. If someone were to ask you what "FISH testing" is, your first thought would probably not be that it is a way to diagnose Down syndrome.

But it is.

FISH actually stands for fluorescent in situ hybridization which is a specialized technique developed by cytogeneticists to diagnose certain chromosome abnormalities. A regular karyotype or chromosome analysis gives you a full picture of the structure of each chromosome as well as the number of chromosomes present in each cell. However, it can take anywhere from 1-2 weeks to get the results of a karyotype. FISH analysis doesn't give you a picture of each chromosome but it does tell you how many copies of a certain chromosome are present in each cell. For example, a FISH test can tell you how many copies of a number 21 chromosome are present in a particular cell. If there are three copies of the number 21 chromosome, rather than two, the individual will have Down syndrome. The main advantage to FISH analysis is that the results only take 2-3 days.

MORE about FISH testing

Which is more important to you - a fast diagnosis, or a more thorough look at all of the chromosomes?