In the March 2017 issue, the piece “A protein puzzle: Untangling the mysterious condition of amyloidosis” (Nat. Med. 23, 266–269, 2017) incorrectly stated that the FDA placed Ionis' NEURO-TTR trial on hold. The FDA had placed a related trial called CARDIO-TTR on hold after some patients in the NEURO-TTR trial developed complications. The error has been corrected in the HTML and PDF versions of this article.