Genetic screening using the colour change of a PNA-DNA hybrid-binding cyanine dye

As the relationship between human genes and various malfunctions and diseases becomes revealed at an ever-increasing pace, the need arises for the develop- ment of rapid genetic screening methods for diagnostic purposes. Genetic diseases show great diversity. Some are caused by a few characteristic localised mutations, while others arise from a large number of variations. Hence, it is unlikely that a single, general diagnostic method that applies to all cases will ever exist. Instead, a combination of methods is frequently applied. Here we propose the use of a dramatic colour change that a cyanine dye, 3,3'-diethylthiadicarbocyanine, displays upon binding to DNA-PNA duplexes. This method could become an inexpensive, fast and simple genetic screening test by visual inspection, with no need for compli- cated equipment. Our results demonstrate that this diagnostic method may be sufficiently sensitive to discriminate between even a fully complementary and a single mutation DNA sequence.