Target amplification systems in nucleic acid-based diagnostic approaches.

Currently, PCR is the standard method for target amplification because it is the oldest and most developed procedure. However, several new alternative approaches for target amplification have recently been developed. Although these new methods are at a relatively early stage of development, each has some advantages over PCR, such as greater amplification per cycle (TAS, 3SR, Q beta), isothermal reaction (3SR), or coupled amplification-mutation detection (LAR/LAS). As a result, each may eventually gain widespread use after further development.