Study: CHN1 Gene, When Mutated, Leads To 'Duane Syndrome'

Study: CHN1 Gene, When Mutated, Leads To 'Duane Syndrome'The Duane syndrome, which is a congenital eye movement disorder and causes eye muscles to contract and relax when they should not, is thought to develop while the child is still in the womb, where it affects the nerve growth in the eye of the child. The people who suffer from this disorder have very limited eye movement sideways, towards the nose or ear. The eyeball pulls into the socket, when the sufferer tries to move the eye towards the nose, often forcing the eye movement up and down.

From quite sometime, the researchers had been trying their level best to find a cure for treating Duane syndrome, and it seems that finally their efforts have paid off. The research teams from the Children’s Hospital in Boston (USA), King’s College London and the Peninsula Medical School, in collaboration, have identified a gene which when mutated causes Duane syndrome.

The findings which were published in Science today, focuses on relation between genetic errors and developmental errors. There is a gene in the human eye called CHN1, which when mutated gives rise to hyperactive gene product called a2 chimerin that adversely affects the normal growth of the eye.

In their study, the researchers isolated CHN1 gene from the families that had the syndrome, and then they did the process of mutation in the chick’s embryo, which is believed to have similar visual system as that of humans. The team found that the process of mutation had led to produce similar defects in nerve growth of the chick embryo as that of humans.

Duane syndrome which causes vision problems is mostly diagnosed in the sufferer by the age of 10, and is more common among females in their left eye. The Duane syndrome can also lead to malformations in the skeleton, eyes, ears, kidneys and nervous system but it occurs in isolation more commonly. It is believed that half a million people around the world is affected by it.

“By understanding how this gene causes Duane syndrome, we can begin to achieve a wider understanding of how the visual system develops in the womb. This raises the possibility of better diagnosis and even genetic treatments for visual conditions such as Duane syndrome,” said Dr. John Chilton, RCUK Academic Fellow in Clinical Neuroscience and Molecular Biology at the Peninsula Medical School.

“We also discovered that the gene responsible for Duane syndrome is widely expressed throughout the nervous system, so the next question to be answered is why only the nerves that control the eye muscles are affected,” added Dr. Chilton.

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