Correction to: Nature Biotechnology https://doi.org/10.1038/s41587-019-0146-7, published online 4 June 2019.

In the version of this article initially published, in reference to Translate Bio’s MRT5201, the sentence “FDA put a clinical hold on this synthetic mRNA drug encoding ornithine transcarbamylase, owing to toxicity and clearance issues” should have read “FDA put a clinical hold on this synthetic mRNA drug encoding ornithine transcarbamylase, pending more toxicology data on clearance times.” The error has been corrected in the HTML and PDF versions of the article.