In the December 2015 issue, the piece “Drugs that made headlines in 2015” (Nat. Med. 21, 1382, 2015) did not specify that the different doses of aducanumab were compared with placebo, and that they were all conducted as part of the same study. The error has been corrected in the HTML and PDF versions of this article.

In the December 2015 issue, the piece “Bias against genetic case reports might compromise medicine” (Nat. Med. 21, 1378, 2015) incorrectly described the relationship between ClinVar and ClinGen. ClinVar is maintained by staff at the US National Center for Biotechnology Information (NCBI) at the National Institutes of Health (NIH) and is supported with intramural funding. In contrast, ClinGen comprises many groups and is funded by grants from the National Human Genome Research Institute. The error has been corrected in the HTML and PDF versions of this article.