A genetic defect that causes some cases of an inherited form of childhood blindness is reported by four independent studies published online this week in Nature Genetics.

Leber congenital amaurosis (LCA) is a severe form of inherited blindness with an early age of onset. Approximately 70% of cases have a known genetic cause, but the underlying genetic basis of the remaining 30% of cases is unknown.

Rui Chen, Josseline Kaplan, Jean-Michel Rozet, Eric Pierce and Ming Qi, and their respective colleagues sequenced all of the protein-coding regions from subjects with LCA of unknown cause and identified mutations in a gene called NMNAT1 as a common cause of this inherited retinal disease.

NMNAT1 encodes an enzyme that catalyzes the synthesis of a molecule called nicotinamide adenine dinucleotide (NAD), which is required for cell survival. The new findings suggest that the NMNAT1 protein acts to protect photoreceptor cells in the retina from degeneration in response to damage or stress.