Should Meredith & Carina Be Worried About DeLuca on 'Grey's Anatomy'? (VIDEO)

DeLuca (Giacomo Gianniotti) is determined to figure out what's wrong with his patient, Suzanne (Sarah Rafferty), but his sister Carina (Stefania Spampinato) is worried about him.

As seen in TV Insider's exclusive sneak peek of Thursday's Grey's Anatomy, she's thinking about the family's history, specifically her father's. (You'll recall that she was the one who noticed signs that their father is bipolar.)

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"I came to Seattle because Andrew is now the same age as our father was when his symptoms started," Carina explains to Meredith (Ellen Pompeo). And it's not just his behavior when it comes to trying to treat Suzanne. "Failing to understand or properly consider the consequences of your actions is a sign of mania," Carina continues.

Watch the clip above to see the examples she lists and Meredith's reaction.

Ellen Pompeo Giacomo Gianniotti Greys Anatomy Season 16 Episode 14

(ABC/Gilles Mingasson)

In "A Diagnosis," DeLuca is irritated when Meredith takes over with Suzanne. Plus, Jackson (Jesse Williams), Owen (Kevin McKidd), and Jo (Camilla Luddington) work on a couple injured in a bear attack, and Levi (Jake Borelli) is hurt when Nico (Alex Landi) doesn't want him to meet his parents.

Grey's Anatomy, Thursdays, 9/8c, ABC