PRNewswire - December 18, 2001

Resistance testing is generally considered to require viral loads of at least 1,000 copies/ml. In one of these two studies addressing the issue, 52% of plasma samples with viral loads below 50 copies/ml were successfully genotyped. A specialized extraction technique was used to obtain sufficient genetic material for the analysis with the TRUGENE test. In the second study, ultracentrifugation was used and samples from all 38 patients with viral loads below 400 copies/ml were successfully genotyped using TRUGENE. Resistance mutations were detected in the majority (30 or 79%) of the patients, suggesting that resistance testing may have utility in early treatment failures.

"The aim of HIV therapy is to reduce viral load to undetectable levels and keep it there", commented Dr. Brendan Larder, Chief Scientific Officer of Visible Genetics. "Once the virus rebounds to any detectable level patients and their physicians would rather not wait until the viral load has increased to levels substantially above 1,000 copies/ml before conducting a resistance test to help select a replacement combination of drugs. The combination of the TRUGENE test and these other specialized techniques could help avoid this wait and associated anxiety."

Results of a third study presented this week indicate that HIV drug resistance testing may be of clinical value before treatment is started. A group in Boston found that 18% of 88 chronically infected patients who had never received antiretroviral therapy were infected with drug resistant virus. A cost-effectiveness analysis of genotypic resistance testing was published earlier this year (Weinstein et al) and included data from clinical trials using the TRUGENE test. Applying the results to these latest data indicates that the cost per quality-adjusted life-year-saved of applying genotypic resistance testing to all chronically-infected patients would be around $20,000. This compares favorably with other widely accepted and reimbursed medical interventions.

Guidelines developed in the past by the International AIDS Society, the US Department of Health and Social Services, the EuroGuidelines group and others recommend resistance testing when treatments fail but suggest that testing before starting therapy should only be 'considered.' This was based on the lack of data about the proportion of patients with detectable drug-resistant virus prior to initiation of therapy.

"These data add to the evidence that large numbers of people are being infected with, and continue to live with, drug resistant virus. Running a resistance test before starting treatment might make a great deal of sense clinically and may be cost-effective," commented Dr. Richard D'Aquila, lead investigator on the Boston Study and now Professor of Medicine at the Vanderbilt University in Nashville, USA.

About the Company

Visible Genetics Inc. is an international leader in the emerging field of pharmacogenomics, which uses genetic information in the identification and analysis of genes to improve patient care and reduce healthcare costs. VGI develops, manufactures and markets high performance automated DNA sequencing systems and complete kits for the analysis of genes linked to disease. The Company's OpenGene(TM) system employs patented CLIP technology -- a single-step, bi-directional sequencing method that significantly reduces the time and cost involved in identifying clinically relevant genetic information. Visible Genetics' TRUGENE(TM) HIV-1 Genotyping Test and OpenGene(TM) System were cleared for sale in September 2001 by U.S. Food and Drug Administration (FDA).

Visible Genetics has its corporate headquarters in Toronto, Canada; its main production facility in Atlanta, USA; its European headquarters in High Wycombe, UK, its research base in Cambridge, UK, operating companies in France, Spain, Italy, Germany, Portugal, Switzerland, Israel and Australia, and is represented in 10 additional countries around the world. The company employs approximately 350 people worldwide.

This press release contains forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. These forward-looking statements are subject to risks, uncertainties and other factors which may cause the Company's results to differ materially from expectations. These include risks relating to our ability to obtain market acceptance of genotyping and the Company's products, delays in, or the refusal of, insurance companies and other third-party payors to reimburse us for our products, delays in product development, our ability to acquire and protect intellectual property important to our business through patents, licenses or other arrangements, claims that our intellectual property may interfere with the rights of others, ability to obtain regulatory approvals, delays in making the new Atlanta manufacturing facility operational, and other risks as detailed from time to time in the Company's SEC filings, including its most recent Annual Report on Form 20-F. These forward-looking statements speak only as of the date hereof. VGI disclaims any intent or obligation to update these forward-looking statements

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