- Model May Accelerate Development of New Therapeutics
For Neurological Disease of Ashkenazi Jews -

THE WOODLANDS, Texas, May 31 /PRNewswire/ -- Lexicon Genetics Incorporated (Nasdaq: LEXG) announced today the application of the Company's proprietary knockout mouse technology to create a model for Canavan disease, a devastating inherited neurological disorder most commonly affecting children in the Jewish population. The knockout mice were developed through a research collaboration between Lexicon and scientists at University of Texas Medical Branch at Galveston. With the high degree of genetic similarity between mice and humans, knockout mouse models have become the gold standard for genome-based drug discovery efforts focused on important human diseases. Details of this important model system were published in the current issue of The Journal of Gene Medicine.

"This is an important advance in the quest to develop new therapeutics for rare or poorly understood genetic diseases such as Canavan disease," stated Dr. Arthur T. Sands, President and Chief Executive Officer of Lexicon. "We are rapidly expanding our portfolio of knockout validated drug targets and mammalian models of human diseases for the discovery of new genomics-based therapies."

"The advantage of this newly developed knockout mouse is that the feasibility of gene therapy can be tried prior to human experimentation in children suffering from this devastating disease," said Dr. Reuben Matalon, Professor of Pediatrics and Human Genetics at Children's Hospital, UTMB, at Galveston and leader of the research team. "This mouse model should provide urgently needed answers to many questions surrounding potential gene therapy treatments for central nervous system conditions." Dr. Matalon intends to make the knockout mice available to the research community through a collaborative network of scientists who are working on Canavan disease as well as other neurological disorders.

Canavan disease is the result of an inherited gene defect causing childhood onset of brain degeneration, mental retardation, reduced muscle tone, and early death. Among the Jewish population of Eastern and Central European descent (Ashkenazi), there is a high carrier frequency of the mutant gene, approximately 1 individual in 40. Approximately 90 percent of the six million Jews in the United States are Ashkenazi Jews. The severity of the disease, poor prognosis, and lack of any conventional medical treatment has led researchers to seek genetic approaches for new therapies. In addition, the American College of Obstetricians and Gynecologists has issued a recommendation to screen Jewish couples to determine whether they are carriers of Canavan disease.

"Attempts to develop effective treatments have been hindered by the lack of any animal model of Canavan disease," said Dr. Ken Platt, Director of Homologous Recombination at Lexicon Genetics and co-author on the publication. "We are very pleased that our knockout mouse technology may accelerate the development of new therapeutic approaches to this disease."

Lexicon Genetics Incorporated is a leader in defining the functions of genes for drug discovery using large-scale knockout mouse technology. Lexicon has invented high-throughput gene trapping technology to discover thousands of genes and expand its OmniBank(R) library of tens of thousands of knockout mouse clones. The Company uses an integrated platform of functional genomic technologies to accelerate large-scale analysis of mammalian gene function for drug discovery. Lexicon's Internet exchange, Lexgen.com(TM), enables researchers worldwide to access the OmniBank library and form collaborations with Lexicon to discover pharmaceutical products based on genes and knowledge of their functions. Lexicon has established functional genomics and OmniBank alliances with many pharmaceutical and biotechnology companies including American Home Products, The R.W. Johnson Pharmaceutical Research Institute, G.D. Searle & Co., Boehringer Ingelheim Pharmaceuticals, N.V. Organon, ZymoGenetics/ Novo Nordisk, DuPont Pharmaceuticals and Millennium Pharmaceuticals, Inc. Additional Company information is available at www.lexicon-genetics.com.

Statements in this press release that are not strictly historical are "forward-looking" statements as defined in the Private Securities Litigation Reform Act of 1995. The actual results may differ materially from those projected in the forward-looking statements due to the risks and uncertainties that exist in Lexicon's filings with the Securities and Exchange Commission. The Company disclaims any obligations to update the statements in this press release.