Scientists have discovered an elusive human gene that causes a devastating form of early-onset blindness, a step they say will help develop sight saving gene therapy for retinal degeneration.

Researchers from the Massachusetts Eye and Ear Infirmary, The Children’s Hospital of Philadelphia, Loyola University Chicago Health Sciences Division have isolated an elusive human gene called NMNAT1 that causes a common form of Leber congenital amaurosis (LCA).

LCA is an inherited retinal degenerative disease characterised by reduced vision in infancy. Within the first few months of life, parents usually notice a lack of visual responsiveness and unusual roving eye movements known as nystagmus.

LCA typically involves only vision problems, but can be accompanied by disease in other organ systems in a minority of patients. It is a common reason children are enrolled in schools for the blind.

“The immediate benefit of this discovery is that affected patients with mutations in this new LCA gene now know the cause of their condition,” Eric Pierce, co-author and director of the Ocular Genomics Institute at Massachusetts said in a statement.

“Scientists now have another piece to the puzzle as to why some children are born with LCA and decreased vision. The long-term goal of our research is to develop therapies to limit or prevent vision loss from these disorders,” Pierce said.

NMNAT1 is the 18th identified LCA gene. The gene resides in a region that was known to harbour an LCA gene since 2003, but the specific disease gene has been undiscovered until now.

These findings will be published in the journal Nature Genetics.

To identify NMNAT1, scientists performed whole exome sequencing of the family of two siblings who initially presented for evaluation of LCA but who had no mutations in any of the known LCA genes.

Researchers found that all but the youngest patient with NMNAT1 mutations had damage to the macula, the centre of the retina that is needed for central vision.

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