Researchers find key to premature ageing

HONG KONG - Scientists have shed new light on why cell repair is less efficient in older people after a breakthrough discovery on premature ageing, a rare genetic disease that affects one in four million babies.

Premature ageing, or Hutchison-Gilford progeria syndrome, is obvious in the appearance of a child before it is a year old. Although their mental faculties are normal, victims stop growing, lose body fat and suffer from wrinkled skin and hair loss.

Like old people, they suffer stiff joints and a buildup of plaque in arteries which can lead to heart disease and stroke. Most die of cardiovascular diseases before they are 20.

In 2003, a team of scientists in the United States found that progeria was caused by mutation in a protein called Lamin A, which lines the nucleus in human cells.

A team at the University of Hong Kong, led by Pofessor Zhou Zhongjun, took the research a step further last year and found that mutated Lamin A actually disrupted the repair process in cells, resulting in accelerated ageing.

The study was published in the latest issue of the Nature Medicine.

Professor Zhou said the team came by their findings after comparing skin cells taken from two progeria sufferers, normal humans, progeria mice and normal mice. While damaged DNA was quickly repaired in the healthy human and mice cell samples, the samples taken from the progeria humans and mice had difficulty repairing damaged DNA.

"Mutation in this protein (Lamin A) can cause defects in repair and thus lead to progeria," he said in an interview. "DNA damage is not effectively repaired in cells with defective Lamin A but very efficiently repaired in normal cells."

- REUTERS