Smaller, more cost efficient system points way to practical DNA analysis platform and individualized treatment regimes

Tokyo -- Toshiba Corporation today announced that it has developed an electrochemical DNA chip that employs an original current detection method to support development of individual treatment regimes for patients infected with hepatitis C. Toshiba holds fundamental patents on an electrochemical detection method for DNA chips, one of the few basic bio-electronic technologies generated in Japan, and is working on a standard platform for DNA-based diagnostic systems.

The hepatitis C virus infects two million people in Japan and over 170 million people around the world. The virus attacks the liver and in chronic cases can result in degenerative diseases, including cirrhosis. Interferon has been identified and promoted as a means to flush hepatitis C viruses from the liver, but the effectiveness of this approach depends on a number of factors, including the type and copy number of infecting viruses and individual patient characteristics. In some patients, the therapy does not work and other treatment is indicated.

Toshiba's electrochemical DNA chip builds on research work conducted at Toshiba Hospital that established a relationship between the therapeutic effect of interferon and the single nucleotide polymorphisms (SNPs) of the host genes. Investigations of 158 chronic type C hepatitis patients confirmed two protein genes as related to interferon receptivity: MxA, which inactivates viruses in cells, and MBL, which binds viruses and inactivates them^*. Osaka University has also reported this relationship.

Toshiba has developed a DNA chip able to carry out SNP typing, working in collaboration with the GeneCare Research Institute Co., Ltd., headed by Dr. Yasuhiro Furuichi. The development project combined GeneCare's DNA analysis technology with Toshiba's state-of-the-art semiconductor and IT-related technologies.

The results of analyses by the DNA chip indicate whether or not interferon will help the patient. In cases where it will prove ineffective, this allows identification of more beneficial treatment regimes. The DNA chip also indicates progressive doses of interferon for patients who will benefit from interferon therapy.

DNA chips have not become a widely used diagnostic tool as they require large equipment and time-consuming detection of genes labeled with expensive fluorescent dyes. The current-detection method, for which Toshiba holds fundamental patents, enjoys significant advantages that include the ability to miniaturize the system and ease of chip mass production.

The company's first target is mass production of the SNP detection chip, with commercialization targeted for fiscal year 2002. Once this is achieved, the next step is a standardized platform for DNA analysis that supports individualized therapy regimes.