Nature Reviews Disease Primers 6, Article number: 22 (2020) https://doi.org/10.1038/s41572-020-0156-2 Published online 02 April 2020

In the originally published article, errors in the affiliations have now been corrected in both the HTML and PDF versions of the article, to state: IBD Center, Department of Gastroenterology, Humanitas Clinical and Research Center – IRCCS –, Rozzano, Italy, and Department of Biomedical Sciences, Humanitas University, Pieve Emanuele, Italy. An error in the Acknowledgements incorrectly attributing funding for Arthur Kaser to Silvio Danese has also been corrected.