CRISPR-Cas9 has been hailed as a breakthrough in genetic engineering, however, new research has indicated the technology may cause unwanted mutations.Likened to ‘molecular scissors’, CRISPR has been used in multiple studies attpting to cure some of mankind’s most debilitating afflictions, including cancer, Parkinson’s disease and blindness.However, when using CRISPR to try and correct blindness in laboratory mice, a research team from the Columbia University Medical Center discovered more than 1,500 unintended single-nucleotide mutations as a result of the treatment. This included more than 100 significant mutations which were either genetic deletions or insertions.It had previously been thought that CRISPR may not be absolutely accurate, but until now the extent to which unwanted mutations could occur was unknown. As a result, it’s hoped this study will be able to help researchers to gain a deeper understanding of the probl.In the past, predictive algorithms have been used to identify areas that might be possibly affected beyond the target area, however, when applied to the mice used in the experiment it failed to detect the unintended mutations.Currently, there are two ongoing human trials in China using CRISPR, while another has been scheduled to occur in the US later this year. It was hoped the same predictive algorithm would be able to be used to identify areas that could be affected beyond the targeted area during the trials, but the revelation anating from Columbia has placed some doubt over its efficacy.However, despite the unintended mutations, the mice appeared to be unaffected and CRISPR had successfully corrected the desired gene and restored their vision. But, the consequences of the study means that not withstanding the extensive measures in place, many scientists will still be wary about using CRISPR praturely in humans.