'Stranger Things' star Gaten Matarazzo to have fourth surgery for rare condition

Fellow cast members and other actors are offering their support to "Stranger Things" star Gaten Matarazzo, who said Wednesday he was having his fourth surgery for a rare genetic condition.

"Surgery number 4! This is a big one!" wrote Matarazzo, 17, on Instagram, alongside a photo of himself in a hospital bed, with a serious look on his face but giving a thumbs-up. "To learn more about Cleidocranial Dysplasia and how you can help those with the condition you can go to ccdsmiles.org," he continued. Cleidocranial dysplasia, or CCD, is a congenital disorder in which the collarbone is underdeveloped or absent, generally accompanied by dental abnormalities.

"Good luck love!!! sending my love gate," commented Millie Bobby Brown, a fellow star of the Netflix drama series about a group of teens in the 1980s facing supernatural forces. "Sending you supernova good vibes. Love you," wrote cast member Cara Buono. Matthew Modine, who played evil scientist Martin Brenner early in the series, told Matarazzo: "Be well brother," adding an emoji of hands clasped in prayer.

Other well-wishers included recurring supporting stars Randy Havens, Andrey Ivchenko, Chester Rushing and Matty Cardarople, as well as former "The Walking Dead" star Michael Cudlitz.

Matarazzo has been an advocate for CCD awareness for years, and his father helped found the nonprofit CCD Smiles, which offers support and resources for afflicted individuals, their families and health care professionals, and works toward passage of a federal bill to ensure that dental surgery for the disorder is covered by health care plans.

In 2016, while appearing with two co-stars on the UK's "The Jonathan Ross Show," Matarazzo explained that CCD "affects your facial growth, your skull growth, it affects your teeth — so that's why I don't have any, these are fake right here. I have teeth, but I mean they're all baby teeth. But I need a lot of surgery. And I have a really mild case and a lot of people have it much worse than I do. And I feel like putting it into the show is really raising awareness for it," he said, referring to his character Dustin Henderson, who also has CCD.

Matarazzo in October 2017 had posted a similar hospital photo as Wednesday's, writing, "Yo dudes! A little pre-op pic before my oral surgery today. One step closer to having my own real teeth eventually." Last March, he uploaded another such image and wrote, "Surgery number three......yippee."

Cleidocranial dysplasia, also known as dento-osseous dysplasia and Marie-Sainton syndrome, usually is caused by a genetic mutation and affects approximately one in every million individuals worldwide, according to the National Institutes of Health.