DNA microchips:: Technical and practical considerations

The development of high throughput techniques, such as DNA microarrays, engages interest in many biomedical research fields. They are becoming one of the preferred methods for large-scale expression analyses. The power of this technology is that it allows the profiling of thousands of genes in one single experiment. There are two main array-based technologies: cDNA and oligonucleotide arrays. cDNA arrays consist of microscope slides or nylon membranes containing hundreds to thousands of immobilized DNA probes, which are hybridized to fluorescent or radioactive complementary cDNA obtained from a target sample. Oligonucleotide chips differ in that probes are 20-25 mer selected oligonucleotides, which are bound to glass substrates and that the DNA obtained from a target sample can only be fluorescently labeled. In this review, we describe the different types of DNA-chips, the steps involved in the production of microchips, the methodological and technical aspects of microchip utilization, and their potential applications including some practical considerations utilizing clinical material.