Reykjavik, ICELAND, December 13, 2002 — deCODE genetics (Nasdaq/Nasdaq Europe:DCGN) announced today that team of deCODE scientists has mapped to a small segment of chromosome 16 a gene contributing to psoriatic arthritis. This represents the first genetic factor outside the major histocompatibility complex (MHC) region on chromosome 6 with significant linkage to any psoriasis-related phenotype. An article describing these findings will appear in the January 2003 edition of the American Journal of Human Genetics and is now accessible in online edition of the journal at www.ajhg.org.

“Our breakthrough findings in psoriasis underscore the unique power of our population approach for tackling the genetics of just about any common condition, and we hope to push this program forward to identify the gene involved as well as targets for the development of new therapies,” said Dr. Kari Stefansson, CEO of deCODE genetics.

Psoriatic arthritis (PsA) is a condition that affects approximately 10% of those who suffer from psoriasis. Like other forms of arthritis, it involves swelling and deterioration of the cartilage in the joints, causing stiffness, pain and disability. Current therapies are focused principally on symptomatic relief, due in part to a lack of understanding of the basic biology of the disease. deCODE’s genetic research is aimed at identifying the genetic factors involved, as a means of identifying new drug and diagnostic targets that can target the underlying cause of disease and point the way towards more effective treatment and prevention strategies.

To map the gene, the deCODE scientists and collaborating doctors from the National University Hospital in Reykjavik identified 178 patients diagnosed with PsA from the nearly 1000 patients participating in the company’s program in psoriasis. Using deCODE’s national genealogy database, 100 of these patients were found to fall into 39 families, and a genome-wide scan was conducted with 1000 microsatellite markers. A suggestive locus on chromosome 16 was then genotyped with a denser marker set, yielding a LOD score of 2.17 for the group as a whole, but a LOD score of 4.19 for those related through their paternal lineage. This is far above the standard criteria for genome-wide significance, and represents the first such genetic factor outside the MHC ever mapped in a psoriatic condition. This locus also overlaps with a significant locus deCODE has identified in osteoarthritis, suggesting that the gene in question may influence the susceptibility of the joints in general, interacting with other genetic or environmental factors that determine the particular type of arthritis that develops. This is a particularly exciting prospect, as it could point the way towards drug targets and the development of broadly applicable new therapeutics that could work to counteract inherited weaknesses in the joints.

About deCODE

deCODE is using population genetics to create a new paradigm for healthcare. With its uniquely comprehensive population data, deCODE is turning research on the genetic causes of common diseases into a growing range of products and services — in gene and drug discovery, DNA-based diagnostics, pharmacogenomics, bioinformatics, and clinical trials. deCODE’s pharmaceuticals group, based in Chicago, and deCODE’s biostructures group, based in Seattle, conduct downstream development work on targets derived from deCODE’s proprietary research in human genetics as well as contract service work for pharmaceutical and biotechnology companies. deCODE is delivering on the promise of the new genetics.SM Visit us on the web at www.decode.com.

Any statements contained in this presentation that relate to future plans, events or performance are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements are subject to a number of risks and uncertainties that could cause actual results to differ materially from those described in the forward-looking statements. These risks and uncertainties include, among others, those relating to technology and product development, integration of acquired businesses, market acceptance, government regulation and regulatory approval processes, intellectual property rights and litigation, dependence on collaborative relationships, ability to obtain financing, competitive products, industry trends and other risks identified in deCODE’s filings with the Securities and Exchange Commission. deCODE undertakes no obligation to update or alter these forward-looking statements as a result of new information, future events or otherwise.