Chicken blindness gene could hold key to many human diseases

Biotechnologist Dr Doug Lester and PhD student Hemanth Tummala were searching for the genetic mutation that causes blindness in certain chickens, but their findings point the way to potentially important new areas of research in human health.

An inherited condition known as retinopathy globe enlarged (RGE) causes affected chickens to go blind within six to eight weeks of hatching.

Working with colleagues from Leeds University and Edinburgh’s Roslin Institute, Dr Lester’s team traced RGE’s cause to a mutation in the GNB3 gene.

The mutation deletes an essential amino acid, preventing GNB3 from playing its proper part in normal eye development.

Because the GNB3 gene is also vital for the normal functioning of important body organs, Dr Lester believes that the mutation might be a key factor in a wide range of disorders in humans.

“It’s probable that a very similar mutation is also responsible for an inherited eye disorder in humans, known as cone-rod dystrophy,” Dr Lester said.

Human cone-rod dystrophy sufferers are sighted at birth, but lose first their central colour vision in early adulthood, before slowly losing their peripheral black and white vision as well.

“Interestingly the human GNB3 gene has not been previously implicated in retinal dystrophy, however a much milder human mutation has been shown to reduce the level of the GNB3 protein by 50% in many tissues of the body and this has been associated with low birth weight, obesity, hypertension, coronary heart disease, type II diabetes and depression,” Dr Lester said.

“Our findings might therefore provide a useful indicator for further research into the pathogenesis of these diseases as well,” he added.

Further studies are now underway to see if the chickens also suffer from hypertension and if humans with inherited retinal degeneration also have mutations in this gene.

The longer-term objective of the research is to develop gene therapy processes to prevent this deterioration in affected individuals or perhaps even to restore the sight of blind people suffering from the condition.