Many exciting advances are being made in the field of microarray technology, but there continue to be several major hurdles for the technology to evolve fully.
1. Regulatory: As demonstrated by the Roche launch of the AmpliChip, there are many FDA regulatory problems that need to be resolved. These include not only the designation as an IVD vs. ASR, but also how to standardize the sample preparation, and the interpretation of results. What would happen to isolated failures? Would failure of one gene or one section of the array invalidate the entire assay? What controls would be required? Many other similar questions would need to be resolved.
2. Quality control: Other FDA issues include quality control in both the design and the manufacturing process of the array itself. One can hope for improvements in microfabrication to minimize defects (and to reduce costs).
3. Cost: The cost per datapoint and cost per assay will need to be comparable to current assays, and in the context of increasing overall medical costs, the array data will likely need to be even more cost-efficient than current tests in order to be competitive.
4. Standardization: Currently genomic expression data is reported in many different ways in the literature. SuperArray (Frederick, MD). is developing a method of reporting expression levels in "copies per microgram of total RNA per cell." This would help to allow researchers in different labs to compare data; however, it does not address the role of alternate splicing of mRNA. This lab-to-lab and platform-to-platform standardization is a major hurdle to widespread routine use of DNA microarrays. The creation of the Genetic Analysis Technology Consortium (GATC), initiated by Affymetrix and Molecular Dynamics, is working to standardize array-based genetic analysis.
5. Sensitivity: Improvements in detection level of RNA to identify rare transcripts is critical to array technology.
6. Ease of use: For DNA microarrays to become universally useful, especially in a large clinical diagnostics lab, the integration of sample preparation with detection and analysis in one machine is fundamental to moving into the diagnostics area.
7. Reimbursement: The problem of who will pay for the adoption of DNA microarray technologies in the clinical setting has yet to be tested. But the ability of microarrays to generate diagnoses in hours rather than days may help to push insurers to cover the cost of the new technologies.
Now that the Human Genome Project is completed, researchers have a nearly complete catalog of all human genes. Because the practice of genomics relies on large-scale, comprehensive analyses of genes, the ability to parallel process expression information using DNA microarrays has become invaluable in genomics research. Advances in our understanding of genomewide expression patterns will foster many uses for microarray technology including: determining the potential for disease, predicting drug response, disease diagnosis and monitoring, bioterrorism surveillance, identifying infectious disease outbreaks, as well as forensic and paternity identification.
Furthermore, the U.S. government has indicated its inclination toward acceptance of genomic data in clinical settings. In 2003, the NIH issued a vision statement describing how genomics can contribute to the future of the practice of medicine and the FDA issued draft guidelines for the submission of genomic data in drug applications [23,24]. In September 2003, J. Craig Venter announced at the 15th Annual Genome Sequencing and Analysis Conference that his Science Foundation would establish a $500,000 cash prize to the person(s) who can develop a whole human genome sequencing technique at a cost of $1,000 per genome. The use of microarrays for DNA sequencing holds great promise for reaching Dr. Venter's goal. The recent increases in funding sources, the creation of new corporate partnerships, the launch of new commercial products and the tantalizing potential for wide-use applications combine to make the future of DNA microarray technology very bright.
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