REJUVENATING treatments for grey hair could have moved a step closer, according to research supported by scientists in Bradford.

A study of DNA samples has identified a gene for grey hair which one day could see people keeping their hair colour for longer.

The research confirms that greying with age is at least partly determined at birth.

Understanding how the IRF4 gene washes colour out of hair might lead to future therapies that halt or reverse the process, scientists believe.

The British-led team also found genes that influence hair curliness and the likelihood of growing a "monobrow".

Professor Desmond Tobin, of the University of Bradford, who led part of the study, said the grey gene discovery was a small but significant step in understanding the ageing process.

He said that the research had potential forensic and cosmetic applications as knowledge increased.

But for those already going grey and those losing their hair, the prognosis isn't good.

Potential treatments are probably still a long way off and even then might not be able to reverse the ageing process, particularly when it comes to going bald.

"I've just turned 50 and I am going grey - it is too for late for us," said Prof Tobin.

"It will be a case of 'catch it before it happens', particularly with balding."

Researcher Dr Kaustubh Adhikari, of University College London, said: "We already know several genes involved in balding and hair colour but this is the first time a gene for greying has been identified in humans, as well as other genes influencing hair shape and density.

"It was only possible because we analysed a diverse melting pot of people, which hasn't been done before on this scale. These findings have potential forensic and cosmetic applications as we increase our knowledge on how genes influence the way we look."

The scientists analysed DNA samples from 6,357 people of mixed ethnic ancestry from five South American countries. Among the volunteers were individuals of European, Native American and African descent, providing a wide range of head hair types.

The IRF4 gene was already known to play a role in hair, skin and eye colour. Hair greying is caused by an absence of the pigment melanin, whose production and storage is regulated by a process involving IRF4.

Study leader Professor Andres Ruiz-Linares, also of University College London, said: "We have found the first genetic association to hair greying, which could provide a good model to understand aspects of the biology of human ageing.

"Understanding the mechanism of the IRF4 greying association could also be relevant for developing ways to delay hair greying."

Another gene, PRSS53, was found to influence hair curliness, with one "new" variant linked to the very straight hair of people from the Far East.

Dr Adhikari added: "The genes we have identified are unlikely to work in isolation to cause greying or straight hair, or thick eyebrows, but have a role to play along with many other factors yet to be identified."

The findings are reported in the journal Nature Communications.