Production has begun in Los Angeles on Season Four of ABC's Golden Globe-winning series Grey's Anatomy.

Entering their first year as residents, Meredith Grey, Cristina Yang, Izzie Stevens and Alex Karev now have interns of their own to mentor. Among the new interns are George, forced to repeat his internship after failing his exams, and Lexie Grey, Meredith's half-sister.

Actress Chyler Leigh joins the cast as Lexie Grey. Born in Charlotte, North Carolina, Leigh has worked with some of the biggest talents in the business, from Aaron Spelling to David E. Kelley. Her television and film credits also include That '80s Show, Reunion and Not Another Teen Movie.

Grey's Anatomy stars Ellen Pompeo as Meredith Grey, Patrick Dempsey as Derek Shepherd, Sandra Oh as Cristina Yang, Katherine Heigl as Isobel "Izzie" Stevens, T.R. Knight as George O'Malley, Justin Chambers as Alex Karev, Chandra Wilson as Miranda Bailey, James Pickens, Jr. as Richard Webber, Sara Ramirez as Callie Torres, Eric Dane as Mark Sloan and Chyler Leigh as Lexie Grey.

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