Diane Barnett-Shapiro, a personal manager with Shapiro/West & Associates for more than 20 years, died Feb. 21 of breast cancer. She was 57.Born and raised in Brooklyn, Barnett-Shapiro worked with clients including Jerry Seinfeld, Carl Reiner, Bill Lawrence, Robert Wuhl and Megyn Price. She was also instrumental in coordinating many of the company’s television and motion picture productions. She is survived by her husband George, her mother, her brother and three stepchildren. Donations may be made to the Jonsson Cancer Center Foundation at UCLA or to the Motion Picture & Television Fund.