My Sister's Keeper

My Sister's Keeper is a 2004 novel written by Jodi Picoult. Set in Rhode Island, it tells the story of a 13-year-old girl named Anna Fitzgerald, a "savior sibling", who sues her parents so that they can no longer legally control her medical decisions once she learns she is expected to donate a kidney to her older sister Kate, who is dying from leukemia, cancer of the blood and bone marrow. It is written in first person, from the perspectives of several main characters. In 2008, the book was adapted into a movie.
Plot summary.
Anna Fitzgerald's older sister, Kate, suffers from acute promyelocytic leukemia, a cancer of the blood and bone marrow. When Anna's parents learn about Kate's diagnosis, they decide to conceive Anna through artificial selection and in vitro fertilization because nobody in the family is a genetic match to donate organs to Kate. Once Anna is born, her umbilical chord blood was used in treatments for Kate to save her life. Although the treatment was initially successful, Kate relapsed (became sick again). Since then, Anna had been used as a donor for any other bodily substance needed to treat Kate, who continues to swing between remission and relapse as she grows up.