This case was presented at Neurology Grand Rounds.

Dr. Louis reports receiving consulting fees from United States Diagnostic Standards and payment for expert testimony in cases involving genetic analyses as evidence of brain-tumor causation on behalf of Rohm and Haas. No other potential conflict of interest relevant to this article was reported.

Disclosure forms provided by the authors are available with the full text of this article at NEJM.org.

This article was updated on May 15, 2014, at NEJM.org.

We thank Dr. Thomas Byrne for help with organizing the conference.