Health Repair with gene scissors can lead to new genetic defects

Under certain circumstances, the targeted correction of faulty sections in the genome can trigger new genetic defects. This was reported by a team from the University of Zurich (UZH) in the case of the rare hereditary disease chronic granulomatosis.

This affects around one in 120,000 people, the University of Zurich announced on Wednesday. The disease impairs the immune system and makes those affected susceptible to serious and life-threatening illnesses. Two letters are missing in the DNA sequence of a gene, which means that an enzyme complex that plays an important role in the defense against bacteria and molds is not produced.

In an experiment on a cell culture of immune cells with the same defects as humans, the researchers succeeded in inserting the missing letters at the correct position in the gene using the CRISPR system. However, entire sections of the chromosome in which the repair took place were missing, as the UZH wrote.

The gene scissors occasionally cut the DNA strand in several places on the chromosome. When these cuts are rejoined, entire sections may be incorrectly arranged or missing. This could have unforeseeable medical consequences and, in the worst case, could also contribute to the development of blood cancer.

The research team tested a number of alternative approaches, but was unable to completely prevent the undesirable side effects with any of these measures.

SDA