SAN DIEGO, CALIFORNIA, June 7, 2005 -- Illumina, Inc. (NASDAQ: ILMN) announced today the commercial availability of two single nucleotide polymorphism (SNP) - based assay panels designed to study genetic variation and function in the MHC region (see Note) of the human genome. The MHC is rich in gene content and genetic diversity, and the region is believed to contribute to the majority of common autoimmune and inflammatory disorders including multiple sclerosis (MS), Type-1 diabetes and rheumatoid arthritis.

Illumina's new panels represent the industry's first-ever MHC-focused SNP panels for high-throughput, array-based analysis. By conducting high-resolution analysis of the MHC across many samples, life science researchers may be able to determine some of the key genes and genetic variants that lead to disease susceptibility. The MHC Exon-Centric Panel consists of 1228 SNPs in or within 10kb of protein-coding regions (exons), while a companion MHC Mapping Panel includes 1,293 SNPs evenly distributed across the entire region.

Illumina has optimized its MHC SNP sequences for the Company's GoldenGate™ genotyping protocol, a high-performance assay method validated by hundreds of millions of genotypes. The MHC panels are used in conjunction with the Company's universal arrays, which are available in two bead-based, multi-sample platforms: the Sentrix Universal-96 Array Matrix and the Sentrix Universal-16 BeadChip, both of which can be imaged on Illumina's BeadArray Reader.

"The MHC is one of the most difficult regions to study due to the high degree of genomic variation," explains Sarah Shaw Murray, Ph.D., Staff Genotyping Science Manager. "Our fine-mapping SNP panels have the potential to provide answers and/or important clues to many unresolved biological mysteries residing in the MHC."

The new MHC panels can be purchased as a standard product --separately or as a set -- by research facilities which have installed Illumina's BeadStation or BeadLab genotyping systems. The panels may also be ordered as part of Illumina's fast-track genotyping service. Depending on study size, running costs per sample (array and reagents) can be less than $100. More information about the MHC panels can be found at: http://10.10.3.242/products/snp/mhc_panelset.ilmn.

"Our new MHC panels represent a powerful new tool for geneticists," stated Jay Flatley, Illumina President and CEO. "For the first time, we're enabling highly focused MHC studies and giving researchers experimental flexibility by making the SNP panels available on two different Sentrix platforms which can accommodate a range of sample throughputs with very attractive per-sample price points. We plan to add at least two more focused genotyping offerings before the end of the year."

Illumina's genotyping product portfolio includes custom and standard products, with focused and whole-genome content, deployed on two different array platforms: the 96-sample Sentrix Array Matrix and the Sentrix BeadChip.

Illumina (www.illumina.com) is developing next-generation tools that permit large-scale analysis of genetic variation and function. The Company's proprietary BeadArray technology -- now used in leading genome centers around the world -- provides the throughput, cost effectiveness and flexibility to enable researchers in the life sciences and pharmaceutical industries to perform the billions of tests necessary to extract medically valuable information from advances in genomics and proteomics. This information will help pave the way to personalized medicine.

"Safe Harbor" Statement under the Private Securities Litigation Reform Act of 1995: this release may contain forward-looking statements that involve risks and uncertainties. Among the important factors that could cause actual results to differ materially from those in any forward-looking statements are the costs and outcome of Illumina's litigation with Affymetrix, market acceptance of Illumina's BeadArray-based products, Illumina's ability to fully develop and commercialize its BeadArray technologies, the Company's ability to successfully commercialize its integrated BeadLab and BeadStation systems for high-throughput genetic analysis, to continue to attract and retain customers in its services and oligonucleotide synthesis operations, to fully develop its BeadArray technologies, to develop and deploy new gene expression profiling and proteomics applications for its platform technology, to manufacture robust Sentrix® arrays and Oligator® oligonucleotides, and other factors detailed in the Company's filings with the Securities and Exchange Commission including its recent filings on Forms 10-K and 10-Q or in information disclosed in public conference calls, the date and time of which are released beforehand. Illumina disclaims any intent or obligation to update these forward-looking statements beyond the date of this release.

MHC Note

Located on the short arm (p) of chromosome 6, the human MHC spans a region of approximately 5 million base pairs (Mb). Within this short length reside over 150 genes, many of which are associated with autoimmune and inflammatory disorders. Over 40% of the genes encode proteins involved in the immune system, including the human leukocyte antigen (HLA) membrane proteins that mediate T-lymphocyte signaling. Linkage disequilibrium (non-random allele pairing) occurs at an unexpectedly high rate in the MHC, influenced principally by low recombination rates and often involving extended haplotypes.

Illumina MHC panel SNP markers exhibit >99.5% concordance with loci mapped by the International HapMap Project and a mean minor allele frequency >20% for all HapMap populations.

Contacts:

Jay Flatley
President & CEO
1.858.202.4501
jflatley@illumina.com

William Craumer
Director, Corporate Communications
1.858.202.4667
bcraumer@illumina.com