A metabolic signature for NADSYN1-dependent congenital NAD deficiency disorder
Justin O. Szot, Hartmut Cuny, Ella M.M.A. Martin, Delicia Z. Sheng, Kavitha Iyer, Stephanie Portelli, Vivien Nguyen, Jessica M. Gereis, Dimuthu Alankarage, David Chitayat, Karen Chong, Ingrid M. Wentzensen, Catherine Vincent-Delormé, Alban Lermine, Emma Burkitt-Wright, Weizhen Ji, Lauren Jeffries, Lynn S. Pais, Tiong Y. Tan, James Pitt, Cheryl A. Wise, Helen Wright, Israel D. Andrews, Brianna Pruniski, Theresa A. Grebe, Nicole Corsten-Janssen, Katelijne Bouman, Cathryn Poulton, Supraja Prakash, Boris Keren, Natasha J. Brown, Matthew F. Hunter, Oliver Heath, Saquib A. Lakhani, John H. McDermott, David B. Ascher, Gavin Chapman, Kayleigh Bozon, Sally L. Dunwoodie
Justin O. Szot, Hartmut Cuny, Ella M.M.A. Martin, Delicia Z. Sheng, Kavitha Iyer, Stephanie Portelli, Vivien Nguyen, Jessica M. Gereis, Dimuthu Alankarage, David Chitayat, Karen Chong, Ingrid M. Wentzensen, Catherine Vincent-Delormé, Alban Lermine, Emma Burkitt-Wright, Weizhen Ji, Lauren Jeffries, Lynn S. Pais, Tiong Y. Tan, James Pitt, Cheryl A. Wise, Helen Wright, Israel D. Andrews, Brianna Pruniski, Theresa A. Grebe, Nicole Corsten-Janssen, Katelijne Bouman, Cathryn Poulton, Supraja Prakash, Boris Keren, Natasha J. Brown, Matthew F. Hunter, Oliver Heath, Saquib A. Lakhani, John H. McDermott, David B. Ascher, Gavin Chapman, Kayleigh Bozon, Sally L. Dunwoodie
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Research Article Reproductive biology

A metabolic signature for NADSYN1-dependent congenital NAD deficiency disorder

Abstract

Nicotinamide adenine dinucleotide (NAD) is essential for embryonic development. To date, biallelic loss-of-function variants in 3 genes encoding nonredundant enzymes of the NAD de novo synthesis pathway — KYNU, HAAO, and NADSYN1 — have been identified in humans with congenital malformations defined as congenital NAD deficiency disorder (CNDD). Here, we identified 13 further individuals with biallelic NADSYN1 variants predicted to be damaging, and phenotypes ranging from multiple severe malformations to the complete absence of malformation. Enzymatic assessment of variant deleteriousness in vitro revealed protein domain–specific perturbation, complemented by protein structure modeling in silico. We reproduced NADSYN1-dependent CNDD in mice and assessed various maternal NAD precursor supplementation strategies to prevent adverse pregnancy outcomes. While for Nadsyn1+/– mothers, any B3 vitamer was suitable to raise NAD, preventing embryo loss and malformation, Nadsyn1–/– mothers required supplementation with amidated NAD precursors (nicotinamide or nicotinamide mononucleotide) bypassing their metabolic block. The circulatory NAD metabolome in mice and humans before and after NAD precursor supplementation revealed a consistent metabolic signature with utility for patient identification. Our data collectively improve clinical diagnostics of NADSYN1-dependent CNDD, provide guidance for the therapeutic prevention of CNDD, and suggest an ongoing need to maintain NAD levels via amidated NAD precursor supplementation after birth.

Authors

Justin O. Szot, Hartmut Cuny, Ella M.M.A. Martin, Delicia Z. Sheng, Kavitha Iyer, Stephanie Portelli, Vivien Nguyen, Jessica M. Gereis, Dimuthu Alankarage, David Chitayat, Karen Chong, Ingrid M. Wentzensen, Catherine Vincent-Delormé, Alban Lermine, Emma Burkitt-Wright, Weizhen Ji, Lauren Jeffries, Lynn S. Pais, Tiong Y. Tan, James Pitt, Cheryl A. Wise, Helen Wright, Israel D. Andrews, Brianna Pruniski, Theresa A. Grebe, Nicole Corsten-Janssen, Katelijne Bouman, Cathryn Poulton, Supraja Prakash, Boris Keren, Natasha J. Brown, Matthew F. Hunter, Oliver Heath, Saquib A. Lakhani, John H. McDermott, David B. Ascher, Gavin Chapman, Kayleigh Bozon, Sally L. Dunwoodie

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Figure 2

Positions of previously and newly identified NADSYN1 variants identified relative to functional protein domains.

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Positions of previously and newly identified NADSYN1 variants identified...
Blue circles indicate variants identified in the current study and respective family (see Figure 1). Other colored circles with numerals indicate study origin of identified variants and the chronology of their identification, respectively. Previously published variants have been reported in refs. 7, 11–13. Solid and dashed lines distinguish missense from presumed loss-of-function variants due to altered reading frame and protein truncation, respectively.