Two English scientists have unlocked the secret to a rare premature ageing disease called Progeria.
Progeria affects one in four million people worldwide
Researchers at Brunel University, west London, found how a mutated gene responsible for the condition works.
It is hoped the discovery will help treatment for age-related conditions such as stroke and heart disease.
The research will be published in Experimental Gerontology. Progeria affects about one in four million people. There are 40 known cases.
The average life expectancy for someone with the condition is about 13 to 14 years old.
Symptoms include baldness, aged-looking skin, dwarfism, and a small face and jaw relative to head size.
Dr Ian Kill, at Brunel, told BBC News Online: "We study Progeria to understand the biological basis of normal ageing.
"People with Progeria die from disease that old people suffer, primarily heart disease and stroke."
Last year, scientists found a mutated form of the gene Lamin A caused Progeria, but they did not understand how it worked.
Now Dr Kill and Dr Bridger have unlocked this mystery.
A typical cell will divide a certain amount of times so that a new set can replace worn out or damaged ones.
As a person ages, cells lose the ability to multiply.
The researchers discovered the mutated form of Lamin A causes cells to divide more rapidly, which causes them to die. It is this process which leads to premature ageing.
"The whole key is in the cells," Dr Kill explains. "There are two components to ageing - environmental factors, such as smoking, exposure to sunlight and diet, and cellular ageing.
"Any insight into premature ageing brings us closer towards finding out more about normal ageing, and how we can work towards improving the health of the elderly."
He said it was too early to say what kind of treatment could be developed from the discovery.
Andrea Lane, senior press officer for Help the Aged, told BBC News Online: "This research is very useful and could possibly provide some insight into the ageing process, and age-related diseases such as heart disease and stroke."