Teenager Hayley Okines, born with Hutchinson-Gilford progeria syndrome (HGPS), was told she would never live past the age of 13 after being diagnosed with the disease but lived four years longer before breathing her last yesterday.
"My baby girl has gone somewhere better. She took her last breath in my arms at 9.39pm," her mother Kerry Okines wrote on her Facebook page.
"The entire Progeria family mourns together with many as we say goodbye to Hayley Okines, our smart, beautiful and spirited English Rose, who passed away today at age 17," The Progeria Research Foundation said.
She had begun pioneering drug treatment in the US to halt the ageing process but had been in hospital with pneumonia and passed away at home, The Telegraph reported.
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Hayley and her family had also raised funds for her medical treatment and sought to improve public understanding of the condition.
Progeria disorder, which makes children age up to 10 times faster than normal, is undetectable at birth and with time results in baldness, aged-looking skin, dwarfism and a small face.
There are only about 50 known cases of the disease in the world.