Oligonucleotide ligation assay (OLA)

In the OLA reaction, two oligonucleotide probes are hybridised
to a DNA sample so that the 3 terminus of the upstream oligo
is adjacent to the 5 terminus of the downstream oligo. If the 3
terminus of the first primer is perfectly matched to its target
sequence, then the probes can be joined together with a DNA
ligase. In contrast no ligation can occur if there is a mismatch
at the 3 terminus of the first oligo. This approach has been
successfully applied to the detection of 31 common mutations
in cystic fibrosis with a commercial kit, and for the detection of
19 common mutations in the LDL receptor gene in
hypercholesterolaemia.