Top 10 Types of RT PCR Tests Buyers Should Know

Type	How It Works	Typical Result	Useful For	Buyer Considerations
1. One-step RT-PCR	Reverse transcription and PCR amplification take place in the same reaction tube.	An amplified target, detected in real time or at the end of the reaction, depending on the assay.	Routine workflows where fewer handling steps and reduced tube transfers are priorities.	Check that the enzyme and reaction chemistry suit the target and sample. The cDNA is generally not available for separate downstream assays.
2. Two-step RT-PCR	RNA is reverse-transcribed in a separate reaction; the resulting cDNA is then used in one or more PCR reactions.	Amplification results from the selected PCR assay or assays.	Studies testing multiple targets from the same cDNA preparation or using cDNA in follow-up work.	Offers flexibility but adds handling steps and potential for contamination. Include the extra preparation time when planning workflow.
3. Probe-based real-time RT-PCR	A target-specific fluorescent probe generates signal during amplification, which an instrument measures cycle by cycle.	A fluorescence amplification curve and, commonly, a Cq/Ct value for a detected target.	Target-specific detection and assays that need to distinguish multiple targets with separate fluorescent channels.	Requires a probe designed for the target. Confirm instrument channel compatibility and that the assay has been validated for the intended use.
4. Dye-based real-time RT-PCR	A fluorescent dye binds double-stranded DNA, and signal is monitored as amplified DNA accumulates.	A fluorescence curve and Cq/Ct value; a melt-curve analysis may be used to assess the amplified product.	Cost-conscious, usually single-target assays where post-amplification melt analysis is appropriate.	The dye can also report nonspecific double-stranded products, so assay specificity and controls are important. It is generally less suited to multiplexing than probe-based detection.
5. Multiplex real-time RT-PCR	Two or more target sequences are amplified in one reaction, typically using distinguishable fluorescent probes.	Separate signals for the included targets and, when designed, an internal control.	Testing several targets in one sample while conserving sample volume and reaction capacity.	Check the instrument’s available channels, target compatibility, and validation data. Multiplex performance can be affected by competition between reactions.
6. Singleplex real-time RT-PCR	One target is measured per reaction using real-time fluorescence detection.	A target-specific amplification curve and Cq/Ct value, if the target is detected within the assay’s validated range.	Focused testing, assay development, or situations where independent target reactions are preferred.	Compare the number of reactions required per sample with a suitable multiplex option. Cq/Ct values alone are not a universal measure of RNA quantity across different assays.
7. Endpoint RT-PCR	After reverse transcription and amplification, the PCR product is assessed at the end of the reaction, often by gel electrophoresis.	A visible product of an expected size or another endpoint signal; standard endpoint results are usually qualitative or semi-quantitative.	Presence-or-absence checks and applications where real-time quantification is not required.	Post-PCR handling can increase contamination risk. Endpoint signal is not equivalent to a validated quantitative RNA measurement.
8. Relative-quantification RT-qPCR	Target Cq/Ct values are compared with a reference gene and a calibrator sample; methods such as ΔΔCq can estimate relative expression.	A relative expression value or fold change, rather than an absolute number of RNA copies.	Comparing gene expression between samples or experimental conditions.	Reference genes must be appropriate and stable for the samples. The calculation also relies on suitable assay performance, including comparable amplification efficiencies for common ΔΔCq use.
9. Standard-curve absolute-quantification RT-qPCR	Sample Cq/Ct values are compared with a dilution series of standards with known concentrations or copy numbers.	An estimated target quantity within the range supported by the standard curve and assay validation.	Applications requiring a concentration or copy-number estimate using a defined standard and calculation method.	Standard quality, dilution accuracy, extraction recovery, and the stated reporting units affect interpretation. Results are not directly comparable across different validated methods without appropriate controls.
10. Reverse-transcription digital PCR (RT-dPCR)	RNA is reverse-transcribed, and the PCR reaction is partitioned into many individual reactions. Target-positive partitions are counted and used to estimate concentration, commonly with Poisson statistics.	An absolute concentration estimate within the assay’s validated range, generally without relying on a standard curve for quantification.	Applications where partition-based counting or absolute quantification is valuable.	Assess instrument and consumable requirements, partition counts, controls, and validated limits. Reverse-transcription efficiency and sample quality still affect RNA measurements.