Recessive Rare Variants in Deoxyhypusine Synthase, an Enzyme Involved in the Synthesis of Hypusine, Are Associated with a Neurodevelopmental Disorder

Mythily Ganapathi, Leah R. Padgett, Kentaro Yamada, Orrin Devinsky, Rebecca Willaert, Richard Person, Ping Yee Billie Au, Julia Tagoe, Marie McDonald, Danielle Karlowicz, Barry Wolf, Joanna Lee, Yufeng Shen, Volkan Okur, Liyong Deng, Charles A. LeDuc, Jiayao Wang, Ashleigh Hanner, Raghavendra G. Mirmira, Myung Hee ParkTeresa L. Mastracci, Wendy K. Chung*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

Hypusine is formed post-translationally from lysine and is found in a single cellular protein, eukaryotic translation initiation factor-5A (eIF5A), and its homolog eIF5A2. Biosynthesis of hypusine is a two-step reaction involving the enzymes deoxyhypusine synthase (DHPS) and deoxyhypusine hydroxylase (DOHH). eIF5A is highly conserved throughout eukaryotic evolution and plays a role in mRNA translation, cellular proliferation, cellular differentiation, and inflammation. DHPS is also highly conserved and is essential for life, as Dhps-null mice are embryonic lethal. Using exome sequencing, we identified rare biallelic, recurrent, predicted likely pathogenic variants in DHPS segregating with disease in five affected individuals from four unrelated families. These individuals have similar neurodevelopmental features that include global developmental delay and seizures. Two of four affected females have short stature. All five affected individuals share a recurrent missense variant (c.518A>G [p.Asn173Ser]) in trans with a likely gene disrupting variant (c.1014+1G>A, c.912_917delTTACAT [p.Tyr305_Ile306del], or c.1A>G [p.Met1?]). cDNA studies demonstrated that the c.1014+1G>A variant causes aberrant splicing. Recombinant DHPS enzyme harboring either the p.Asn173Ser or p.Tyr305_Ile306del variant showed reduced (20%) or absent in vitro activity, respectively. We co-transfected constructs overexpressing HA-tagged DHPS (wild-type or mutant) and GFP-tagged eIF5A into HEK293T cells to determine the effect of these variants on hypusine biosynthesis and observed that the p.Tyr305_Ile306del and p.Asn173Ser variants resulted in reduced hypusination of eIF5A compared to wild-type DHPS enzyme. Our data suggest that rare biallelic variants in DHPS result in reduced enzyme activity that limits the hypusination of eIF5A and are associated with a neurodevelopmental disorder.

Original languageEnglish (US)
Pages (from-to)287-298
Number of pages12
JournalAmerican journal of human genetics
Volume104
Issue number2
DOIs
StatePublished - Feb 7 2019

Funding

We thank the families for their generous contribution. We also thank Matchmaker exchange/Genematcher for connecting us with the other families. We thank Patricia Lanzano for her technical expertise. These studies were supported by grants from the SFARI at the Simons Foundation , the JPB Foundation , and the DHPS Foundation . T.L.M. was supported by a Career Development Award from the Juvenile Diabetes Research Foundation ( 5-CDA-2016-194-A-N ). R.G.M. was supported by National Institutes of Health grants ( R01 DK60581 and P30 DK097512 ). M.H.P. was supported by the intramural program of the National Institute of Dental and Craniofacial Research, National Institutes of Health . We thank the families for their generous contribution. We also thank Matchmaker exchange/Genematcher for connecting us with the other families. We thank Patricia Lanzano for her technical expertise. These studies were supported by grants from the SFARI at the Simons Foundation, the JPB Foundation, and the DHPS Foundation. T.L.M. was supported by a Career Development Award from the Juvenile Diabetes Research Foundation (5-CDA-2016-194-A-N). R.G.M. was supported by National Institutes of Health grants (R01 DK60581 and P30 DK097512). M.H.P. was supported by the intramural program of the National Institute of Dental and Craniofacial Research, National Institutes of Health.

Keywords

  • DHPS
  • DOHH
  • deoxyhypusine synthase
  • eIF5A
  • exome sequencing
  • hypusination
  • hypusine
  • inborn errors of metabolism
  • neurodevelopmental disorder
  • polyamine pathway

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

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