Transgenomic discovers novel BLOCker-Sequencing technology

Transgenomic, Inc. (OTC Bulletin Board: TBIO) today announced that it has discovered a novel sequencing technology, which the company has termed BLOCker-Sequencing (BLocking Oligonucleotides in Cycle sequencing), which enhances the limit of detection of standard Sanger Sequencing, enriches for direct sequencing of mutated DNA over wild-type (unmutated DNA) and can be run on standard Sanger Sequencing equipment.  

BLOCker-Sequencing is an approach which selectively blocks the sequencing of wild-type DNA and allows samples with lower concentrations of mutant DNA to be sequenced for any mutation using standard Sanger Sequencing techniques.  BLOCker-Sequencing can be easily used with any PCR amplified nucleic acid fragment with minimal modifications to the standard cycle sequencing protocols.

BLOCker-Sequencing incorporates two additional steps prior to annealing of the sequencing primer in the standard Sanger sequencing protocol, a hybridization of a blocking oligonucleotide which is complementary to the wild-type DNA sequence and then a denaturing step at a critical temperature at which the BLOCker-oligo remains annealed to the wild-type sequence but not the mutant sequence.  The sequencing primer will then preferentially anneal and sequence the mutant but not the wild-type DNA.  

Dr. Katherine Richardson, Transgenomic's Vice President of Research and Development, said, "Standard Sanger Sequencing is considered by many to be the gold standard in mutation detection and identification.  However, it has limitations in finding low level DNA mutations such as those found in many cancers.   If you have a tumor with a mutant to wild-type ratio of 1:10 or lower, you will most likely not detect the mutation using standard sequencing techniques.  By adding BLOCker-Sequencing to the Sanger Sequencing protocol, we have shown we can identify mutations in samples with a mutant to wild-type ratio of 1:100.  We have also shown that BLOCker-Sequencing can discriminate different viral strains which co-elute using DHPLC.  The studies we have performed to date prove that BLOCker-Sequencing is a pivotal methodology for enhancing the mutation detection capabilities of Sanger Sequencing to levels equal to or better than commercially available allele-specific, pyrosequencing and next generation sequencing methods."

Craig Tuttle, Chief Executive Officer and President of Transgenomic commented, "BLOCker-Sequencing is a very exciting discovery.   Our studies have shown that BLOCker-Sequencing will provide a key enhancement to standard Sanger Sequencing.  It extends the utility of using Sanger Sequencing to easily and sensitively measure somatic mutations in cancer similar to how it is used in other areas of diagnostic medicine to measure germ line mutations.  In addition, BLOCker-Sequencing can be combined with our COLD-PCR technologies to provide ultra-sensitive DNA mutation detection allowing us to look for DNA mutations in a patient's blood sample rather than requiring a tumor sample.  Offering a BLOCker-Sequencing and COLD-PCR kit will extend the ability of labs to employ our combined technology for ultra-sensitive mutation detection using equipment and techniques they already have and are widely accepted by regulatory agencies worldwide as the gold standard for mutation detection.  We believe BLOCker-Sequencing coupled with COLD-PCR could revolutionize mutation detection assay technology."

A provisional patent for this new discovery has been filed in the United States.