Page last updated at 17:03 GMT, Wednesday, 16 September 2009 18:03 UK

'Gene cure' for colour blindness

Advertisement

Watch the squirrel monkey 'cured' of colour blindness. When untreated, he could only guess where to touch. (Footage courtesy of Neitz Laboratory.)

Scientists say they are a step closer to curing colour blindness using gene therapy.

A US team were able to restore full colour vision to adult monkeys born without the ability to distinguish between the colours red and green.

Nature journal describes the technique used by the researchers at the University of Washington.

Although more studies are needed, the same treatment may work for humans who are colour blind, experts believe.

Full colour

Until now scientists had not thought it was possible to manipulate the adult brain in this way.

It was considered that adding new sensory information, such as the visual receptors necessary for perfect colour vision, could only be done in the earliest years of life when the brain is at its most malleable or "plastic".

But Professor Jay Neitz and his team were able to introduce therapeutic genes into the light-sensing cells at the back of the eye of adult male squirrel monkeys.

This provides a positive outlook for the potential of gene therapy to cure adult vision disorders
The study authors

The therapeutic genes contained the necessary DNA code to enable the light-sensing cells to distinguish between red and green - something lacking in the male monkeys.

Tests revealed the gene therapy was a success. The male monkeys now possessed the necessary photopigments to see all colours and were able to correctly pick out red from green on computer image tests.

The monkeys were treated over two years ago and their improvement in colour vision has remained stable since.

Professor Neitz's team will continue to monitor the animals to evaluate the long-term treatment effects.

They are hopeful that a similar therapy could benefit people who are colour blind.

"This provides a positive outlook for the potential of gene therapy to cure adult vision disorders," they said.

There are several forms of colour blindness. The most common form is inherited red/green colour blindness, passed on through a faulty colour vision gene on an X chromosome.

Colour blindness test
A person with normal colour vision will be able to see the eye in this image

Sometimes colour blindness occurs because of diseases such as macular degeneration or from side effects of medicines.

Winfried Amoaku, an expert in ophthalmology at the University of Nottingham, said the research could eventually benefit approximately 7% of males and 1% of females born with genetic colour deficiencies.

He said: "These research seems to be the first in primates to address the colour vision deficiencies and indicate that intact cells are modifiable in their colour perception.

"Further research is required, however, before this comes to human clinical trials, and therapy in the clinics."



Print Sponsor


SEE ALSO
Colour blindness not all it seems
06 Dec 05 |  Health
Colour blindness cell loss clue
04 Jun 04 |  Health

RELATED BBC LINKS

RELATED INTERNET LINKS
The BBC is not responsible for the content of external internet sites


FEATURES, VIEWS, ANALYSIS
Has China's housing bubble burst?
How the world's oldest clove tree defied an empire
Why Royal Ballet principal Sergei Polunin quit

BBC navigation

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.

Americas Africa Europe Middle East South Asia Asia Pacific