Signed! The Contortionist's Handbook by Craig Clevenger (2002, MacAdam/Cage) 805

The Contortionist's Handbook is the story of John Dolan Vincent, an abnromally gifted child with a prclivity for mathematics beyond his years. However, he also bears a rare deformity—polydactylism—and his genius is counterbalanced by a near absence of social skills and episodes of severe migraines.

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