DNA mutation breakthrough could help treat TB, cancer

A DNA mutation is any change that occurs in the DNA. These changes can be beneficial to, have some effect on, or be seriously detrimental to an organism. Each cell depends on thousands of proteins to do their jobs in the right places at the right times. Sometimes, mutations prevent one or more of these proteins from working properly. By changing a gene’s instructions for making a protein, a mutation can cause the protein to malfunction or to be missing entirely. When a mutation alters a protein that plays a critical role in the body, it can disrupt normal development or cause a medical condition.

Researchers have developed a new method to that has the capability of looking at a specific segment of DNA and point out a single mutation, which could help diagnose and treat diseases like cancer and tuberculosis.These small changes can be the root of a disease or the reason some infectious diseases resist certain antibiotics.

For example, tuberculosis -- a disease that's known to have drug-resistant strains. Its resistance to antibiotics often is due to a small number of mutations in a specific gene. If a person with tuberculosis isn't responding to treatment, it's likely because there is a mutation.

The new method has improved on previous approaches because their solution doesn`t require any complicated reactions or added enzymes, it just uses DNA. Their method is robust to changes in temperature and other environmental variables, making it well-suited for diagnostic applications in low-resource settings.

Lead author Georg Seelig, a University of Washington assistant professor of electrical engineering and of computer science and engineering along with David Zhang of Rice University and Sherry Chen, a UW doctoral student in electrical engineering, designed probes that can pick out mutations in a single base pair in a target stretch of DNA.

The probes allow researchers to look in much more detail for variations in long sequences - up to 200 base pairs - while current methods can detect mutations in stretches of up to only 20 bp.

In this method, testing probes are designed to bind with a sequence of DNA that is suspected of having a mutation. The researchers do this by creating a complimentary sequence of DNA to the double-helix strand in question. Then, they allow molecules containing both sequences to mix in a test tube in salt water, where they naturally will match up to one another if the base pairs are intact. Unlike previous technologies, the probe molecule checks both strands of the target double helix for mutations rather than just one, which explains the increased specificity.

The probe is engineered to emit a fluorescent glow if there`s a perfect match between it and the target. If it doesn`t illuminate, that means the strands didn`t match and there was in fact a mutation in the target strand of DNA.

The findings have been published online in the journal Nature Chemistry.