Gaten Matarazzo was born with cleidocranial dysplasia (CCD), a rare genetic condition that affects bone and dental development. This fact is confirmed by reputable sources including his biography and public interviews.

Cleidocranial dysplasia often affects the development of collarbones and teeth, and is caused by a mutation in a gene related to bone formation. People with CCD may have delayed or missing adult teeth, extra teeth, and underdeveloped collarbones, though the severity of symptoms varies widely.

Gaten has shared publicly that he has a mild case of CCD. In interviews, he has explained that his condition has given him both challenges and opportunities. He has said that because of CCD, he needed dental procedures and surgeries as a child, and that finding dentists familiar with the condition was sometimes difficult.

In one published interview, Gaten described his experience with CCD as “pretty good” and noted that it has not led to bullying or prevented him from doing normal activities. He has said that having a mild form of the condition allowed him to live like many other kids, and that his CCD ultimately helped open doors in his acting career.

The creators of Stranger Things incorporated CCD into his character Dustin Henderson’s storyline after learning about Gaten’s real-life condition. This has brought rare clinical visibility to CCD on mainstream television and helped educate a global audience about the condition.

Gaten has also spoken about how CCD influenced how others saw his lisp and dental development as a child. In one recounting with a dental school dean, he shared that as a young teen he had trouble finding specialists who understood his needs, and that his dental work included removing extra or delayed teeth as part of his care over the years.

Rather than hide his condition, Gaten has chosen to speak about it publicly. He has said that using his platform to raise awareness and advocate for understanding CCD is important, in part because many other people with the condition face more severe challenges.