Hayley Okines, teen with premature aging disease Progeria, dies at 17

Hayley Okines, a teenage girl who became an inspiring advocate for those suffering from the rare, premature aging disease Progeria, has died at the age of 17.

"The world is waking up to the loss of our beautiful Hayley," her mother posted on Facebook, and tributes quickly began to pour in.

The Progeria Research Foundation wrote, "The entire Progeria family mourns together with many as we say goodbye to Hayley Okines, our smart, beautiful and spirited English Rose."

Hayley's impact stretched a long way from the town in East Sussex, England, where she was born with the fatal genetic condition. Progeria appears to cause accelerated aging in children, and those born with it rarely live beyond their mid-teens. The disease is so rare, experts say there are only about 200 cases in the world.

The most serious complication of Progeria is that children develop premature, progressive heart disease at a very young age. Progeria researchers hope that a better understanding of this rare condition could also prove useful for the millions of people worldwide who suffer heart disease later in life, as part of the normal aging process.

Hayley memorably told her story in her 2011 book, "Old Before My Time," and a recently published memoir, "Young at Heart."