Page iv: Cover illustration credits were inadvertently omitted:

Illustration: fetal brain (26 weeks gestational age), courtesy of Barbara J. Crain,M.D., Ph.D., Johns Hopkins University School of Medicine, Baltimore, MD and Hannah C. Kinney,M.D., Childrens Hospital Boston and Harvard Medical School, Boston, MA. Cover design: Sharon N. Blackburn, B.A., Johns Hopkins University School of Medicine, Baltimore, MD.

Page v: Dedication text was inadvertently omitted:

Dedicated to those who live with and care f or children and adults with autism, and those who strive through science to understand and treat them.