This is one of the few novels I have heard about that talks about prosopagnosia. The main character learns about the condition in the process of being diagnosed after a head injury.
Amazon.com: The Echo Maker: A Novel: Books: Richard Powers:
From Publishers Weekly
Starred Review. A truck jackknifes off an 'arrow straight country road' near Kearney, Nebr., in Powers's ninth novel, becoming the catalyst for a painstakingly rendered minuet of self-reckoning. The accident puts the truck's 27-year-old driver, Mark Schluter, into a 14-day coma. When he emerges, he is stricken with Capgras syndrome: he's unable to match his visual and intellectual identifications with his emotional ones. He thinks his sister, Karin, isn't actually his sister—she's an imposter (the same goes for Mark's house). A shattered and worried Karin turns to Gerald Weber, an Oliver Sacks–like figure who writes bestsellers about neurological cases, but Gerald's inability to help Mark, and bad reviews of his latest book, cause him to wonder if he has become a 'neurological opportunist.' Then there are the mysteries of Mark's nurse's aide, Barbara Gillespie, who is secretive about her past and seems to be much more intelligent than she's willing to let on, and the meaning of a cryptic note left on Mark's nightstand the night he was hospitalized. MacArthur fellow Powers (Gold Bug Variations, etc.) masterfully charts the shifting dynamics of Karin's and Mark's relationship, and his prose—powerful,"