Friends and colleagues were caught off-guard by the announcement, but said it made sense.
"What scientist do you know who got a major research project - the human genome project - and a major piece of legislation passed?" said Tim Leshan, the genome institute's policy chief from 2001 to 2006.
Karen H. Rothenberg, dean of the University of Maryland School of Law, who often collaborates with Collins, said it wasn't easy to run a government science institute.
"It's a lot to ask anybody to be in such a political position and serve so many heads of NIH and politicians for so long," she said.
Nonetheless, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said Collins gave him the impression during a talk on Tuesday night that the high stress of leading an institute wasn't a factor in the decision to leave.
"He's accomplished an incredible amount. He did what he set out to do. And I think he wants to look forward to different challenges," Fauci said.
In an e-mail to friends and colleagues, Collins said he had been weighing his departure for a while. He told reporters that the passage of the Genetic Information Nondiscrimination Act was a key factor, and said Dr. Elias A. Zerhouni, the NIH director, tried to talk him out of stepping down.
Collins may have given the best explanation for his decision in a commencement address early this month. He advised new graduates of the University of Maryland, Baltimore, to "nurture the four food groups of a balanced life," which he said were work, faith, love and fun. To further describe fun, he took out a guitar, joked that "I always wanted to play the 1st Mariner Arena" and began strumming his own version of "My Way."
"With me, I hope you'll see the double helix is a highway," he sang.
jonathan.rockoff@baltsun.com
