Ligase Chain Reaction

Ligase Chain Reaction (LCR)

Summary

Ligase chain reaction (LCR) is the method which detects a specific nucleotide sequence with some similarities to polymerase chain reaction. It is similar to polymerase chain reaction (PCR) as it uses DNA polymerase and specific primers designed to bind to the target. However, it is unlike to PCR as the primers are not used to amplify the DNA sequence between the primers. In the presence of target sequences, both primers will hybridize in such a way that one primer will lie directly to the second primer of the pair. In the presence of DNA ligase, these two primers are joined to form a single strand and the target sequence will have been effectively duplicated. In the presence of a mutation or if the target sequence is not present, the primers will not bind and ligation will not occur. As the cycle is repeated, only the target sequence (if it is present) is amplified. LCR exploits four primers to obtain only two types of information: (1) presence of adjacent target sequences, and (2) presence of perfect complementarity to the primers at the junction of these sequences. LCR amplification derives the specificity from the initial hybridization of primer to target DNA. This specificity is enhanced by the use of oligonucleotides and temperatures near the oligonucleotide Tm. In LCR there are two important factors which are the design of primers and LCR conditions.
LCR assays have been developed for the detection of genetic diseases as well as for the detection of bacteria and viruses. In many of these applications, LCR is preceded by an initial PCR step to achieve a greater sensitivity of the respective assays.

Ligase Chain Reaction (LCR)

Introduction

A method of detecting a specific nucleotide sequence with some similarities to polymerase chain reaction. Like PCR, it uses DNA polymerase and specific primers designed to bind to the target. However, unlike PCR, the primers are not used to amplify the DNA sequence between...