Scientists Make Headway in Fighting Childhood Blindness

This discovery could help in the diagnosis and treatment of children who would otherwise begin to lose their vision at an early age.

The search began in Fall 2004, when scientists were researching Joubert Syndrome — a ciliopathic brain disorder that affects children. The disease can cause mental retardation, a loss of balance, the growth of extra fingers or toes and, occasionally, retinal blindness.

To study the causes behind Joubert Syndrome, scientists looked to a gene called “Abelson helper integration site-1,” or AHI1, that had previously been linked to ciliopathies.

According to graduate student Carrie M. Louie, who led the research project, scientists began the study by removing AHI1 in mice to see if its absence would cause problems in brain development resembling those caused by Joubert Syndrome.

“We try to link the genes in the body to their function, what they’re doing and what kind of diseases they can cause when the function is blocked,” Joseph Gleeson, associate professor of neuroscience and the project’s faculty supervisor, said.

Louie found that the mice did not have the same brain development problems present in those suffering from Joubert Syndrome. However, a closer examination showed that the mice were completely blind.

Without AHI1, photoreceptors — also known as rods and cones — are obstructed by photopigments that build up to toxic levels in the eye and preventing normal vision.

After working with mice, the researchers wanted to see whether the absence of the gene was contributing to other diseases where blindness is a symptom.

“We generated a mouse model to study the gene functions and we discovered that the mouse had severe blindness,” Louie said. “We studied this further, and we wanted to see whether [the absence of AHI1] causes blindness in human patients with diseases other than Joubert syndrome.”

They screened a group of European patients with cystic kidney disease — a ciliopathy that has properties similar to Joubert Syndrome — and found that those lacking AHI1 were more likely to go blind.

With this knowledge, new therapies and ways of screening early onset blindness are now possible.

This discovery will help develop of new drugs and improve techniques for diagnosing retinal diseases, which affect 5 to 10 percent of the population. Scientists will also be better equipped to tackle other ciliopathies, such as obesity, mental impairment, and liver fibrosis.

“We built the foundation for new leads to gene therapy,” Louie said. “It’s a step toward helping people figure out what your genes are doing.”

Readers can contact Regina Ip at [email protected].

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