**8.5 HPE-PCR**

*Genetic Engineering - A Glimpse of Techniques and Applications*

Some of the important variants of PCR are described below:

the PCR detection more convenient and fast [57, 58].

mutations that cause beta thalassemia [62], etc.

**8. Variants of PCR**

**8.1 Extreme PCR**

**8.2 Photonic PCR**

**8.3 COLD-PCR**

**8.4 Nanoparticle-PCR**

and bioterrorism pathogens [56].

study gene expression [7, 52, 53]. A variant of the RTP, called differential-display reverse transcription-PCR or RNA arbitrarily primed PCR (RAP-PCR), is used to study and compare the gene expression of organism grown under different conditions. The variant employs the use of short and random 10-mer or 11-mer radio-labeled primers that are annealed at low stringency conditions to promote the extension of random sequences during the first PCR cycle. This is followed by high-stringency cycles to extend the products of first cycle. The resulting products are analyzed using standard sequencing gels, and RAP-PCR fingerprints are visualized by autoradiography. The technique is extremely useful in studying tissue-specific and condition-specific gene expressions [54, 55].

In addition to the above mentioned techniques, numerous other variants of PCR are in use to serve a wide variety of research, diagnostic, and industrial needs, e.g., after exponential PCR, allele specific PCR, asymmetric PCR, arbitrary PCR, core sample PCR, degenerate PCR, dial-out PCR, digital PCR, high-fidelity PCR, hot start PCR, in silico PCR, inter-sequence PCR, ligation-mediated PCR, mini primer PCR, nanoparticle-PCR, overlap-extension PCR, solid-phase PCR, splicing by overlap/overhang extension PCR, suicide PCR, thermal asymmetric interlaced PCR, etc.

In extreme PCR the concentration of primers and polymerase is increased 10–20 times; the amplification rate of instrument reaches about 0.4–2.0 s/. When the primers' concentration is more than 10 mol/L, the polymerase concentration is 1 mol/L, and the extreme PCR is suitable for rapid detection of virulent infectious

It is achieved by fast heating and based on energy conversion, thus shortening the PCR time. The specific process is carried out by using electronic resonance light emitting diode. The energy conversion process is more rapid than the conventional cooling process, causing amplification of target DNA within 5 min and thus making

It is a low denatured temperature-PCR for enriching mutant genes by reducing the reactive temperature of PCR. The basic principle is founded on the base mismatch in any strand of DNA affecting the denaturation temperature. Therefore, the denaturation temperature of the mutant DNA is often lower than that of wild type DNA. The assay is often used for viral gene mutation [59] detection, cancer associated gene mutations (p53) [60, 61], EGFR, KRAS, etc.), beta globulin (HBB)

Gold nanoparticles have superior electrical, optical, thermal, and catalytic activities and have the same properties as single-stranded binding proteins (ssb), which bind to single-stranded DNA and do not interact with double-stranded DNA. Therefore, the

**22**

It is an amplification technique for templates with long DNA chains and large numbers of CTG repeats involving the increase in the denaturation temperature of PCR to solve the problem of high content of DNA (G+C) [64].
