Fluorescent in situ hybridization (FISH)

A laboratory technique that helps diagnose Williams syndrome among other disorders (and also various forms of mosaicism).  A DNA probe for the elastin gene is made with a fluorescent label, and mixed with a sample of the patient’s DNA.  If the elastin DNA is present, the probe will be attached (hybridise).  This allows a determination of whether there are one or two copies of the elastin gene present. 

See DNA (deoxyribonucleic acid), Elastin (gene), Mosaicism, Williams syndrome