Mutations can be detected directly in an active gene

The green spots represent the normal variant of the gene and the red the mutated variant that causes cancer and commonly occurs in our most prevalent tumor diseases.

The new method is used directly in cell preparations and tissue sections and makes it possible to study the effect of genetic variation in patient samples in general and in cancer sample in particular.

“The method enables the study of biological processes in individual cells instead of reading an average condition for many cells,” says Mats Nilsson, professor of molecular diagnostics at the Department of Genetics and Pathology.

The method is an elaboration of an earlier technology, where probes, or “padlock molecules,” are used to identify individual molecules in individual cells. These probes are known for their capacity to distinguish between similar sequences and are therefore very well suited for mutation analysis, for instance. By reinforcing the signal of the probes, the researchers were able to use them in microscopic preparations, and the researchers can now see, for the first time, the occurrence of different gene variants at the mRNA level, that is, in the molecules that are produced by active genes.

This means that processes in cells that there are only very few of in a sample can be identified with the signal being “drowned out” by the signals generated by the cells that are in the majority. This is of interest in studying tumor material, for instance, where cancer cells occur in the midst of healthy cells.

“This quite simply makes it possible to find a needle in a haystack. For the patient this means a considerably more sensitive and more specific diagnosis, and the possibility of implementing the right treatment is enhanced,” says Mats Nilsson.

The method will also be of use in studying whether a gene variant impacts different types of cells or tissues in different ways, which is difficult with techniques that study material prepared from many cells in a tissue.

The scientists in the project, which is part of the Science for Life Laboratory (SciLifeLab) collaboration, are no continuing to refine the method for parallel identification of several different molecules at the same time and for analyses of biobank material.

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Molecular tools

Science for Life Laboratory Uppsala (SciLifeLab)