The mother of a Cumbrian teenager undergoing brain surgery, is asking people to wear purple to raise awareness of his condition.
Daniel Gordon, 13, from Brampton, has the rare condition Chiari, which can affect the brains and spines of around one in 1,200 people.
He's undergoing surgery today, because the bottom of his brain is pressing onto his spinal cord, causing dizziness and nausea.
It's the second time he'll have had an operation because of the condition.
Vikki Gordon, his mum, has set up the Purple Thursday Facebook group to raise awareness: