Leber congenital amaurosis (LCA) is a blinding retinal disease that presents within the first year after birth. Using exome sequencing, we identified mutations in the nicotinamide adenine dinucleotide (NAD) synthase gene NMNAT1 encoding nicotinamide mononucleotide adenylyltransferase 1 in eight families with LCA, including the family in which LCA was originally linked to the LCA9 locus. Notably, all individuals with NMNAT1 mutations also have macular colobomas, which are severe degenerative entities of the central retina (fovea) devoid of tissue and photoreceptors. Functional assays of the proteins encoded by the mutant alleles identified in our study showed that the mutations reduce the enzymatic activity of NMNAT1 in NAD biosynthesis and affect protein folding. Of note, recent characterization of the slow Wallerian degeneration (Wlds) mouse model, in which prolonged axonal survival after injury is observed, identified NMNAT1 as a neuroprotective protein when ectopically expressed. Our findings identify a new disease mechanism underlying LCA and provide the first link between endogenous NMNAT1 dysfunction and a human nervous system disorder.
Subscribe to Journal
Get full journal access for 1 year
only $17.42 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
NCBI Reference Sequence
Patel, V.P. & Chu, C.T. Nuclear transport, oxidative stress, and neurodegeneration. Int. J. Clin. Exp. Pathol. 4, 215–229 (2011).
Lassmann, H. Mechanisms of neurodegeneration shared between multiple sclerosis and Alzheimer's disease. J. Neural Transm. 118, 747–752 (2011).
Wishart, T.M. et al. Design of a novel quantitative PCR (QPCR)-based protocol for genotyping mice carrying the neuroprotective Wallerian degeneration slow (Wlds) gene. Mol. Neurodegener. 2, 21 (2007).
Ludwin, S.K. & Bisby, M.A. Delayed wallerian degeneration in the central nervous system of Ola mice: an ultrastructural study. J. Neurol. Sci. 109, 140–147 (1992).
Hoopfer, E.D. et al. Wlds protection distinguishes axon degeneration following injury from naturally occurring developmental pruning. Neuron 50, 883–895 (2006).
Feng, Y., Yan, T., He, Z. & Zhai, Q. WldS, Nmnats and axon degeneration—progress in the past two decades. Protein Cell 1, 237–245 (2010).
Lunn, E.R., Perry, V.H., Brown, M.C., Rosen, H. & Gordon, S. Absence of Wallerian degeneration does not hinder regeneration in peripheral nerve. Eur. J. Neurosci. 1, 27–33 (1989).
Gillingwater, T.H. & Ribchester, R.R. Compartmental neurodegeneration and synaptic plasticity in the Wlds mutant mouse. J. Physiol. (Lond.) 534, 627–639 (2001).
Mack, T.G. et al. Wallerian degeneration of injured axons and synapses is delayed by a Ube4b/Nmnat chimeric gene. Nat. Neurosci. 4, 1199–1206 (2001).
Araki, T., Sasaki, Y. & Milbrandt, J. Increased nuclear NAD biosynthesis and SIRT1 activation prevent axonal degeneration. Science 305, 1010–1013 (2004).
Zhai, R.G. et al. Drosophila NMNAT maintains neural integrity independent of its NAD synthesis activity. PLoS Biol. 4, e416 (2006).
Avery, M.A., Sheehan, A.E., Kerr, K.S., Wang, J. & Freeman, M.R. WldS requires Nmnat1 enzymatic activity and N16-VCP interactions to suppress Wallerian degeneration. J. Cell Biol. 184, 501–513 (2009).
Conforti, L. et al. Reducing expression of NAD+ synthesizing enzyme NMNAT1 does not affect the rate of Wallerian degeneration. FEBS J. 278, 2666–2679 (2011).
Niven, J.E. & Laughlin, S.B. Energy limitation as a selective pressure on the evolution of sensory systems. J. Exp. Biol. 211, 1792–1804 (2008).
den Hollander, A.I., Roepman, R., Koenekoop, R.K. & Cremers, F.P. Leber congenital amaurosis: genes, proteins and disease mechanisms. Prog. Retin. Eye Res. 27, 391–419 (2008).
Wang, H. et al. Mutations in SPATA7 cause Leber congenital amaurosis and juvenile retinitis pigmentosa. Am. J. Hum. Genet. 84, 380–387 (2009).
Estrada-Cuzcano, A. et al. IQCB1 mutations in patients with Leber congenital amaurosis. Invest. Ophthalmol. Vis. Sci. 52, 834–839 (2011).
Wang, X. et al. Whole-exome sequencing identifies ALMS1, IQCB1, CNGA3 and MYO7A mutations in patients with Leber congenital amaurosis. Hum. Mutat. 32, 1450–1459 (2011).
Keen, T.J. et al. Identification of a locus (LCA9) for Leber's congenital amaurosis on chromosome 1p36. Eur. J. Hum. Genet. 11, 420–423 (2003).
Zhou, T. et al. Structure of human nicotinamide/nicotinic acid mononucleotide adenylyltransferase. Basis for the dual substrate specificity and activation of the oncolytic agent tiazofurin. J. Biol. Chem. 277, 13148–13154 (2002).
Coleman, M.P. & Freeman, M.R. Wallerian degeneration, wlds, and nmnat. Annu. Rev. Neurosci. 33, 245–267 (2010).
Sasaki, Y. & Milbrandt, J. Axonal degeneration is blocked by nicotinamide mononucleotide adenylyltransferase (Nmnat) protein transduction into transected axons. J. Biol. Chem. 285, 41211–41215 (2010).
Conforti, L. et al. NAD+ and axon degeneration revisited: Nmnat1 cannot substitute for WldS to delay Wallerian degeneration. Cell Death Differ. 14, 116–127 (2007).
Li, H. & Durbin, R. Fast and accurate short read alignment with Burrows-Wheeler transform. Bioinformatics 25, 1754–1760 (2009).
McKenna, A. et al. The Genome Analysis Toolkit: a MapReduce framework for analyzing next-generation DNA sequencing data. Genome Res. 20, 1297–1303 (2010).
Shen, Y. et al. A SNP discovery method to assess variant allele probability from next-generation resequencing data. Genome Res. 20, 273–280 (2010).
Challis, D. et al. An integrative variant analysis suite for whole exome next-generation sequencing data. BMC Bioinformatics 13, 8 (2012).
Balducci, E. et al. Assay methods for nicotinamide mononucleotide adenylyltransferase of wide applicability. Anal. Biochem. 228, 64–68 (1995).
Prudencio, M., Durazo, A., Whitelegge, J.P. & Borchelt, D.R. An examination of wild-type SOD1 in modulating the toxicity and aggregation of ALS-associated mutant SOD1. Hum. Mol. Genet. 19, 4774–4789 (2010).
We thank all of the individuals with LCA and their parents who were involved in this study. We thank R. Sifers for scientific discussion and J.E. Zaneveld for critical reading of the manuscript. R.K.K. is supported by the Foundation Fighting Blindness Canada, the Canadian Institutes for Health Research, the US National Institutes of Health (NIH), Reseau Vision, the Fonds de la Recherche en Santé du Québec (FRSQ) and FORGE Canada. We acknowledge the FORGE Canada Consortium. We thank R. Pigeon for coordinating all the individuals with LCA. G.A.F. acknowledges the Pangere Corporation, Grousbeck Foundation and the Wynn-Gund Foundation for financial support. We sincerely acknowledge The Royal Society (C.T. is a university research fellow), Yorkshire Eye Research and The Sir Jules Thorn Charitable Trust (grant 09/JTA). Exome sequencing was performed at the BCM–Functional Genome Initiative (BCM-FGI) core facility, which is supported by NIH shared instrument grant 1S10RR026550 to R.C. H.W. was supported by postdoctoral fellowship F32EY19430. J.C. was supported by the Graduate Innovation Foundation of Hunan Province (CX2011B388). This work is supported by grants from the Retinal Research Foundation and the National Eye Institute (R01EY018571) to G.M. and R.C.
The FORGE Steering Committee comprises K. Boycott (leader; University of Ottawa, Ottawa, Ontario, Canada), J. Friedman (co-lead; University of British Columbia, Vancouver, British Columbia, Canada), J. Michaud (co-lead; Université de Montréal, Montreal, Quebec, Canada), F. Bernier (University of Calgary, Calgary, Alberta, Canada), M. Brudno (University of Toronto, Toronto, Ontario, Canada), B. Fernandez (Memorial University, St. John's, Newfoundland, Canada), B. Knoppers (McGill University, Montreal, Quebec, Canada), M. Samuels (Université de Montréal, Montreal, Quebec, Canada) and S. Scherer (University of Toronto, Toronto, Ontario, Canada). This work was funded in part by the Government of Canada through Genome Canada, the Canadian Institutes of Health Research and the Ontario Genomics Institute (OGI-049). Additional funding was provided by Genome Quebec and Genome British Columbia. We thank J. Marcadier (Clinical Coordinator) and C. Beaulieu (Project Manager) for their contribution to the infrastructure of the FORGE Canada Consortium.
The authors declare no competing financial interests.
Members of the Steering Committee are given in the Acknowledgments.
About this article
Cite this article
Koenekoop, R., Wang, H., Majewski, J. et al. Mutations in NMNAT1 cause Leber congenital amaurosis and identify a new disease pathway for retinal degeneration. Nat Genet 44, 1035–1039 (2012). https://doi.org/10.1038/ng.2356
Nicotinamide mononucleotide adenylyltransferase uses its NAD+ substrate-binding site to chaperone phosphorylated Tau
Nicotinamide Mononucleotide: A Promising Molecule for Therapy of Diverse Diseases by Targeting NAD+ Metabolism
Frontiers in Cell and Developmental Biology (2020)
Morpho-functional survey in children suspected of inherited retinal dystrophies via video recording, electrophysiology and genetic analysis
International Ophthalmology (2020)
Translational Vision Science & Technology (2020)