How to Measure Gene Activity Using Competitive PCR Kits
A laboratory method and kit for accurately measuring how much a specific gene is being used by cells by comparing it against a known internal standard.
Original patent title: “Method for quantitative measurement of gene expression using multiplex competitive reverse transcriptase-polymerase chain reaction”
A laboratory method and kit for accurately measuring how much a specific gene is being used by cells by comparing it against a known internal standard. Granted to University of Rochester in 1997 with 7 claims and 151 forward citations.
Key facts
Coverage
What does this patent actually cover?
This patent describes a kit used to quantify gene expression in small biological samples. It works by performing a multiplex reaction, meaning it amplifies both a target gene and a 'housekeeping' gene (a gene that is always active) at the same time. The kit includes competitive templates for both genes, which are nearly identical to the natural genes but contain a small point mutation. By adding these templates, researchers can compare the amount of product from the natural gene against the known amount of the competitive template, allowing for a precise calculation of how much of the target gene was originally present.
The gap
What does this patent NOT cover?
- Does not cover non-competitive PCR methods where no internal standard template is used.
- Does not cover gene expression measurement techniques that rely on sequencing or hybridization arrays.
- Does not cover the use of competitive templates that differ from the target by more than a point mutation.
- Does not cover methods that amplify the target and housekeeping genes in separate, non-multiplexed reactions.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
By using a competitive template that is nearly identical to the target gene, the method ensures that both the target and the competitor compete equally for the same primers and enzymes, effectively canceling out variations in reaction efficiency.
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Oncology research for measuring tumor gene expression
Molecular diagnostic assays
Gene expression profiling in clinical biopsies
Why it matters
The bigger picture
Before this method, quantifying gene expression in tiny tissue samples was notoriously difficult and prone to error. This approach provided a standardized way to normalize data using housekeeping genes, which became a staple technique in molecular biology research for studying diseases like cancer.
Filed
January 28, 1994
Granted
June 17, 1997
Market context
Who's building on this
Companies in this space
This technology laid the groundwork for modern quantitative PCR (qPCR) workflows. Companies like Thermo Fisher Scientific, Bio-Rad, and Roche have built extensive product lines around the principles of multiplexing and internal controls for gene expression analysis.
Market impact
The standardization of competitive PCR helped transition gene expression studies from qualitative observations to rigorous quantitative science. It enabled more reliable comparisons across different labs and experiments, becoming a foundational tool in the development of molecular diagnostics.
Claim 1 — Plain English
What this patent covers
This patent describes a kit used to quantify gene expression in small biological samples. It works by performing a multiplex reaction, meaning it amplifies both a target gene and a 'housekeeping' gene (a gene that is always active) at the same time. The kit includes competitive templates for both genes, which are nearly identical to the natural genes but contain a small point mutation. By adding these templates, researchers can compare the amount of product from the natural gene against the known amount of the competitive template, allowing for a precise calculation of how much of the target gene was originally present.
The clever bit
By using a competitive template that is nearly identical to the target gene, the method ensures that both the target and the competitor compete equally for the same primers and enzymes, effectively canceling out variations in reaction efficiency.
What it does not cover
- Does not cover non-competitive PCR methods where no internal standard template is used.
- Does not cover gene expression measurement techniques that rely on sequencing or hybridization arrays.
- Does not cover the use of competitive templates that differ from the target by more than a point mutation.
- Does not cover methods that amplify the target and housekeeping genes in separate, non-multiplexed reactions.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
PatentBrief Score
Impact Score
Strong
Citation count
40/40
Highly cited
Claim breadth
5/20
Moderate scope
Recency
0/20
Older than 20 years
Assignee scale
20/20
Major company or institution
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$135K – $432K
Midpoint $270K · expired or expiring · industry ×3.0
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
The original legal language
Original claims
7 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Willey, J. C. (1997). How to Measure Gene Activity Using Competitive PCR Kits (U.S. Patent No. 5,639,606). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/5639606/quantitative-pcr
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How to Measure Gene Activity Using Competitive PCR Kits cover?
A laboratory method and kit for accurately measuring how much a specific gene is being used by cells by comparing it against a known internal standard.
Who owns patent US 5639606?
University of Rochester owns this patent, granted in 1997.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 5639606 cited by?
This patent has been cited by 151 later patents that build on its ideas.
What problem does this patent solve?
Before this method, quantifying gene expression in tiny tissue samples was notoriously difficult and prone to error. This approach provided a standardized way to normalize data using housekeeping genes, which became a staple technique in molecular biology research for studying diseases like cancer.
What does this patent NOT cover?
Does not cover non-competitive PCR methods where no internal standard template is used.
Patent monitoring