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'Grey's Anatomy': 15 Most Memorable Cases

15. IZZIE'S DAUGHTER
Season 3, ''Time After Time''

What a small world it is when the child Izzie (Katherine Heigl) gave up as a teen reemerges at Seattle Grace in need of a bone marrow transplant. Of course the do-gooder suffers through the painful test, even though the adoptive parents won't let Izzie visit her toe-headed doppelgänger.