An important technique that relies on
hybridisation of complementary nucleic acid sequences is:
Fluorescent In Situ Hybridisation or FISH.
This technique makes use of fluorescent probes to detect and locate
specific DNA sequences in cells and tissues.
In human genetics, FISH is commonly used to analyse the chromosomal
content of cells and to detect mutational changes in chromosomes,
for example, a 22q11 deletion associated with DiGeorge syndrome.
FISH is so sensitive that it can detect single copies of specific
genes in individual cells.