labelled target DNA

Alternatively, the probes may be immobilised to the
membrane and hybridised with the labelled target DNA, that is
free in solution (the reverse dot-blot approach). It is this basic
principle that has been developed into the so-called “gene
chip” technology. In this technique, literally thousands of short
DNA probe molecules are first attached to silica-based support
materials. The DNA under investigation is then fluorescently
labelled and hybridised to the probe matrix. The large number
of probes used enables the pattern of hybridisation to be
translated into sequence information. At present, however, the
high cost of this approach means that it is of limited value for
the analysis of rare disease genes in a diagnostic setting.