Implications for the ligase chain reaction in gastroenterology

The ligase chain reaction (LCR) is a new DNA detection method that uses thermostable ligase to discriminate exquisitely and amplify single base changes in genes of medical interest. This enzyme specifically links two adjacent oligonucleotides when hybridized to a complementary target only when the nucleotides are perfectly base-paired at the junction. Oligonucleotide products are exponentially amplified by thermal cycling of the ligation reaction in the presence of a second set of adjacent oligonucleotides, complementary to the first set and the target. A single-base mismatch prevents ligation and amplification, thus distinguishing a single base mutation from the normal allele. The use of a thermostable ligase allows the enzyme to survive thermal cycling in a fashion analogous to Taq polymerase in the polymerase chain reaction. The assay is compatible with nonradioactive detection and has the potential for automation. Although still in its early stages of development, LCR is expected to find many uses in the field of gastroenterology and in medicine in general. In this review we briefly describe how LCR works and discuss potential areas of application in gastroenterology.