Vision researchers at the University of Utah Moran Eye Center have discovered the gene mutations responsible for a common type of cataract in children.

The study, recently reported in The Journal of Medical Genetics, found mutations in the PITX3 gene in four unrelated families from three ethnic backgrounds who have congenital posterior polar cataracts.

Cataracts are the leading cause of blindness in children and as many as 30 percent of childhood cataracts are this type, which is also one that is more difficult to remove surgically without complications, said Dr. Kang Zhang, associate professor, who headed the study.

Zhang said the researchers believe the discovery of the mutation may one day lead to a genetic test so that even infants at risk of developing the cataract could be spotted before vision loss occurred.

If the cataract occurs, it has to be dealt with early on.

"It's a particularly dangerous condition in infants and young children whose visual systems are developing. If an infant can't see, the connections in the brain won't properly form. If the eye doctor removes the cataract but doesn't do it in time, it can still lead to permanent blindness with a condition called amblyopia, Zhang said.

The scientists hope the discovery will eventually lead to gene therapy, to prevent children from facing the visual losses or ever needing to undergo the surgery.

The gene was earlier found to be involved in other types of cataracts, but these particular mutations appear in much higher proportion than was previously known in terms of causing congenital cataracts, Zhang said. Two other gene mutations have also been linked to this type of cataract.

The hope is that identifying genetic mutations will lead to better screening, earlier diagnosis and ultimately better treatments.

The study also involved investigators from University College of London's Institute of Ophthalmology, Moorfields Eye Hospital in London and the Chinese Academy of Military Science in Beijing. The study subjects were from the United States, Britain and China.

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