What can be measured by gene chips?
Gene chip technology can be used for three main applications: 1. Gene expression profiling: RNA extracted from a biological sample is applied to the microarray. The result reveals the level of expression of tens of thousands of genes, effectively all the genes in the genome, in that sample. This result is known as a gene expression profile or signature. 2. Genotyping: DNA, extracted from a biological sample, is amplified by the polymerase chain reaction and applied to the microarray. The genotype for hundreds or thousands of genetic markers across the genome can be determined in a single experiment. This approach has considerable potential in risk assessment, both in research and clinical practice. 3. DNA sequencing: DNA extracted from a biological sample is amplified and applied to specific sequencing microarrays. Thousands of base pairs of DNA can be screened on a single microarray for mutations in specific genes whose normal sequence is already known. This greatly increases the scop
