single DNA probe

Alternatively, a single DNA probe corresponding to a
specific locus can be used. Hybridisation reveals fluorescent
spots on each chromatid of the relative chromosome.
This method is used to detect the presence or absence of
specific DNA sequences and is useful in the diagnosis of
syndromes caused by sub-microscopic deletions, such as
William syndrome, or in identifying carriers of single gene
defects due to large deletions, such as Duchenne muscular
dystrophy.