Gaten Matarazzo was born with heartbreaking condition that's been written into entire Stranger Things series

As the final instalment of Stranger Things hits screens as we enter 2026, the rare condition one of its lead stars was born with has been explored in and out of the show.

Back in July 2016, fans were first introduced to the Netflix cast, and they began to fall in love with the lovable character of Dustin Henderson, who is played by Gaten Matarazzo.

While in the show it was commonly mentioned that Dustin didn’t have teeth, despite his co-stars all having their gnashers out at their young ages, it was quickly revealed that the cause was due to a rare genetic condition.

Matarazzo has a condition called 'cleidocranial dysplasia', which impacts around one person in one million people, per Johns Hopkins Medicine’s website.

Gaten Matarazzo was born with a genetic condition (Netflix)

Essentially, it’s a disorder that affects a person's bone and tooth development.

The 23-year-old actor, who shared a terrifying warning ahead of the show's final episode, has been open about living with cleidocranial dysplasia, and even revealed in the past that it was the reason he was able to get into acting.

Matarazzo told Health Insight: “Pretty much every part I’ve booked is because of the condition. In some way, it affects me — whether it be my height or my teeth or making me look younger.”

However, he went on to say that he didn’t want it to define his career moves, adding: “Hopefully, I can evolve from that and not just get roles because of the condition, I can play parts that don’t have physical disabilities or anything like that. I can play someone who isn’t associated with the condition.”

But when it came to Stranger Things, Matarazzo admitted that creators Matt and Ross Duffer ‘helped a lot’ when they ‘incorporated’ the condition into the show.

The star revealed it wasn’t the initial plan, ‘but when I told them about it they liked the idea of having a character with a disability to give him more of a unique twist and make him more relatable in a way’.

In an interview on The Doctors, Matarazzo also revealed that they checked with him first about some themes in Stranger Things.

The actor said: “They asked me if it was okay if the kids in the show had bullied me because of it. I said it’s totally cool. It’s realistic.”

The actor said he wants to bring awareness to the condition (Netflix)

He also once explained that cleidocranial dysplasia means he was 'born without collarbones'.

During an appearance on The Jonathan Ross Show in 2016, Matarazzo shared: “It's a condition where you are born without your collarbones; I don't have any. It affects your facial growth, your skull growth, it affects your teeth. That's why I don't have any - these are fake - I have teeth but they're all baby teeth.

“I just want to raise awareness for it and let people know that it's not something that you should be afraid of showing.”

Stranger Things Season 5 Volumes 1 and 2 are now streaming on Netflix. The finale lands at 1am on 1 January 2026.