Sarah Chalke's Grey's Gig Inspired by Son's Deadly Disease

She immediately contacted Grey's creator Shonda Rhimes, who jumped on the idea. Fast-forward to tonight's episode—Chalke plays a single mom of a 4-year-old boy fighting for his life when he develops Kawasaki disease.

Chalke admits she was nervous going into the shoot, especially about seeing a little boy made to look like he had the horrible illness.

But then she got a sign that everything was happening for a reason. One of the three triplets cast to play her son had Kawasaki disease a year ago. "Casting didn't know this, and his mother didn't know the storyline until after she accepted the part and read the script the night before the shoot," Chalke said. "What are the chances of that happening? Zero! It made me feel like, OK, this was all meant to be."

To learn more about Kawasaki disease, go to KDFoundation.org.

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