Melas (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) syndrome is a form of mitochondrial disease.
Mitochondrial disease is where a person is born with a genetic fault causing an inability to produce enough energy from the mitochondria present in cells.
A spokesperson from the Lily Foundation charity said mitochondrial disease affects about one in 4,300 people.
Melas is usually passed down through families, but not everyone will develop symptoms, and those with them can have symptoms varied in type and severity.
“There aren’t enough words to put it into play,” George told the BBC. “It’s horrible, horrific.
Something you never, ever expect as a 16/17 year old boy – losing that sort of family instantly.”
After years of suffering with seizures and stroke-like episodes, George’s eldest brother, Mark, died in 2015 from what they later found out was Melas syndrome.
George’s mother soon faced the same prognosis. About eight months later, she died.
Six years later, George returned from a family holiday to find out that his brother, Liam, had also died from Melas syndrome.