Last year, a study published in the journal Nature Methods caused controversy in the scientific community after claiming to find over 100 unintended large genetic deletions or insertions related to the CRISPR gene-editing process. Now the journal has officially retracted the paper after a thorough review found the main claims in the study were not sufficiently backed up by data.

With several human clinical trials involving the CRISPR gene-editing process moving forward, the original study resulted in a flurry of criticism from many scientists in the field. Geneticists argued the study was fundamentally flawed, with a low sample size and conclusions that could not be reasonably attributed to the data gathered.

Gaetan Burgio, a geneticist from Australia National University, was one of the researchers ardently critical of the study, directing a degree of concern at the journal for publishing such as dubious paper in the first place.

"This is a terrible paper and as a reviewer I would have dissmiss (sic) it from the first round of review," Burgio wrote. "This is a worrying trend from 'high impact' journals to promote the hype over good science. The publication of this paper is clearly a failure in the peer review process."

Now the journal Nature Methods has finally responded to the controversy, publishing several critiques of the original study and officially retracting the paper after a review by four independent referees. An accompanying editorial from the journal concluded that the paper's conclusions were not sufficiently supported by the data. The journal also notes its peer review process for this particular paper was not suitably rigorous.

"The original paper was peer reviewed, but we should have sought at least one additional referee with expertise in the genetics of inbred mouse strains. We regret this omission," the editors of the journal write in a recently released statement. "While ensuring appropriate referee expertise is a task we have always taken seriously, and is a central part of the editorial process, we have now put in place further processes to reduce the likelihood that such an error will happen again."

Last week, the scientists behind the original study also published a pre-print article outlining follow-up research that suggested the original results could not be replicated. Further whole-genomic study of mice that had undergone CRISPR gene-editing were found to have no excess, off-target mutations. The new article, yet to be peer-reviewed or published, concludes, "Taken together, these whole-genome-sequencing-level results support the idea that in specific cases, CRISPR-Cas9 editing can precisely edit the genome at the organismal level and may not introduce numerous, unintended, off-target mutations."

The response from Nature Methods concludes by outlining several other whole-genome studies that have been published suggesting CRISPR gene-editing does not result in significant off-target effects. But, it also notes that there are limitations in the current literature and relatively little published data on the effects of the CRISPR process in vivo.

Although this particular study has now officially been retracted it doesn't mean that CRISPR is 100 percent safe. While many geneticists are undoubtedly breathing a sigh of relief and continuing their research, there still is much more work to be done to understand the broader genomic effects of this revolutionary technique.