Gaten Matarazzo is undergoing a fourth surgery for a rare genetic disorder.
The 17-year-old Stranger Things star took to Instagram this week, sharing a pic of himself in the hospital.
"Surgery number 4! This is a big one!" he captioned it. "To learn more about Cleidocranial Dysplasia and how you can help those with the condition you can go to ccdsmiles.org."
Matarazzo received plenty of love from his fans and celebrity friends on social media, including Stranger Things co-star Millie Bobby Brown. "Good luck love!!!" she wrote. "Sending my love gate."
According to National Institutes of Health (NIH), Cleidocranial Dysplasia is a condition that primarily affects the development of the bones and teeth. Matarazzo opened up about the disorder during his appearance on The Doctors in January 2018, and explained how it was written into the popular Netflix series.
"I think what The Duffer Brothers, the directors of the show, really wanted to do, they wanted to make sure each character in the show was unique, and they had something that was realistic and personal," he shared. "They didn't want cookie-cutter; they wanted unique characters that were relatable and were different."
"So when they heard I had the condition, I told them ... when I was just stretching in the audition room," he continued, adding that casting directors noticed his shoulders were touching. "I was like, 'Yeah, I was born without collarbones.' I started explaining what it was, and how I had a condition from birth. And that it affects my teeth and everything, and that's why I was missing teeth the first season."
Matarazzo said that once he got the part of Dustin Henderson, the Duffer Brothers then told him they were going to incorporate Cleidocranial Dysplasia into his character's storyline.
"They used it in a realistic way," he recalled. "They asked me if it was OK if the kids in the show had bullied me because of it. And I said, 'That's totally cool. It's realistic."
Hear more in the video below.