A GeneChip® apparatus was donated IIR by the Danish Rheumatism Association in 1999.

• Doublestranded cDNA is synthesized from total mRNA purified from the tissue under investigation.
• cRNA, tagged with biotin, are transcribed from the double-stranded cDNA.
• Tagged cRNA molecules are hybridized with the oligonucleotide probes (with known sequences) on the GeneChip.
• Unhybridized cRNA is washed away, and the hybridized, biotin-tagged cRNA reacts with streptavidin-phycoerythrin conjugate.
• A laserscanner read-out shows which of the chip-oligonucleotide probes that have hybridized to the cRNA molecules.

The perspectives of the microchip technology for development of new therapies are considerable. It is now possible in a few hours to investigate the genome of an individual, including which of approximately 50% of his/hers 35,000 genes that are active. It is likely that many diseases can be defined on the basis of their gene expression patterns, or mutations, for example by investigating a blood sample or a tissue specimen from a diseased area. The technique also enables investigations of genetic risk factors for example underlying vascular diseases, cancer, and acute and chronic inflammatory diseases, including infections. In the latter case, the genomes of infectious organisms can be investigated as well, thus giving information not only on the infectious organism causing a disease but also how each individual responds to this particular microbe.