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Loss of UGP2 in brain leads to a severe epileptic encephalopathy, emphasizing that bi-allelic isoform-specific start-loss mutations of essential genes can cause genetic diseases.

Perenthaler, E; Nikoncuk, A; Yousefi, S; Berdowski, WM; Alsagob, M; Capo, I; van der Linde, HC; van den Berg, P; Jacobs, EH; Putar, D; et al. Perenthaler, E; Nikoncuk, A; Yousefi, S; Berdowski, WM; Alsagob, M; Capo, I; van der Linde, HC; van den Berg, P; Jacobs, EH; Putar, D; Ghazvini, M; Aronica, E; van IJcken, WFJ; de Valk, WG; Medici-van den Herik, E; van Slegtenhorst, M; Brick, L; Kozenko, M; Kohler, JN; Bernstein, JA; Monaghan, KG; Begtrup, A; Torene, R; Al Futaisi, A; Al Murshedi, F; Mani, R; Al Azri, F; Kamsteeg, E-J; Mojarrad, M; Eslahi, A; Khazaei, Z; Darmiyan, FM; Doosti, M; Karimiani, EG; Vandrovcova, J; Zafar, F; Rana, N; Kandaswamy, KK; Hertecant, J; Bauer, P; AlMuhaizea, MA; Salih, MA; Aldosary, M; Almass, R; Al-Quait, L; Qubbaj, W; Coskun, S; Alahmadi, KO; Hamad, MHA; Alwadaee, S; Awartani, K; Dababo, AM; Almohanna, F; Colak, D; Dehghani, M; Mehrjardi, MYV; Gunel, M; Ercan-Sencicek, AG; Passi, GR; Cheema, HA; Efthymiou, S; Houlden, H; Bertoli-Avella, AM; Brooks, AS; Retterer, K; Maroofian, R; Kaya, N; van Ham, TJ; Barakat, TS (2020) Loss of UGP2 in brain leads to a severe epileptic encephalopathy, emphasizing that bi-allelic isoform-specific start-loss mutations of essential genes can cause genetic diseases. Acta Neuropathol, 139 (3). pp. 415-442. ISSN 1432-0533 https://doi.org/10.1007/s00401-019-02109-6
SGUL Authors: Maroofian, Reza

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Abstract

Developmental and/or epileptic encephalopathies (DEEs) are a group of devastating genetic disorders, resulting in early-onset, therapy-resistant seizures and developmental delay. Here we report on 22 individuals from 15 families presenting with a severe form of intractable epilepsy, severe developmental delay, progressive microcephaly, visual disturbance and similar minor dysmorphisms. Whole exome sequencing identified a recurrent, homozygous variant (chr2:64083454A > G) in the essential UDP-glucose pyrophosphorylase (UGP2) gene in all probands. This rare variant results in a tolerable Met12Val missense change of the longer UGP2 protein isoform but causes a disruption of the start codon of the shorter isoform, which is predominant in brain. We show that the absence of the shorter isoform leads to a reduction of functional UGP2 enzyme in neural stem cells, leading to altered glycogen metabolism, upregulated unfolded protein response and premature neuronal differentiation, as modeled during pluripotent stem cell differentiation in vitro. In contrast, the complete lack of all UGP2 isoforms leads to differentiation defects in multiple lineages in human cells. Reduced expression of Ugp2a/Ugp2b in vivo in zebrafish mimics visual disturbance and mutant animals show a behavioral phenotype. Our study identifies a recurrent start codon mutation in UGP2 as a cause of a novel autosomal recessive DEE syndrome. Importantly, it also shows that isoform-specific start-loss mutations causing expression loss of a tissue-relevant isoform of an essential protein can cause a genetic disease, even when an organism-wide protein absence is incompatible with life. We provide additional examples where a similar disease mechanism applies.

Item Type: Article
Additional Information: © The Author(s) 2019 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Keywords: ATG mutations, Epileptic encephalopathy, Essential gene, Founder mutation, Genetics, Microcephaly, Recurrent mutation, Start-loss mutation, UGP2, Whole exome sequencing, 1103 Clinical Sciences, 1109 Neurosciences, Neurology & Neurosurgery
SGUL Research Institute / Research Centre: Academic Structure > Molecular and Clinical Sciences Research Institute (MCS)
Journal or Publication Title: Acta Neuropathol
ISSN: 1432-0533
Language: eng
Dates:
DateEvent
March 2020Published
9 December 2019Published Online
3 December 2019Accepted
Publisher License: Creative Commons: Attribution 4.0
Projects:
Project IDFunderFunder ID
91617021ZonMW VeniUNSPECIFIED
NARSAD Young Investigator awardBrain and Behavior Research Foundationhttp://dx.doi.org/10.13039/100000874
RSP-2019/38King Saud Universityhttp://dx.doi.org/10.13039/501100002383
M#UM1HG006504-05National Institutes of Healthhttp://dx.doi.org/10.13039/100000002
MR/S01165X/1Medical Research Councilhttp://dx.doi.org/10.13039/501100000265
MR/S005021/1Medical Research Councilhttp://dx.doi.org/10.13039/501100000265
G0601943Medical Research Councilhttp://dx.doi.org/10.13039/501100000265
WT093205MAWellcome Trusthttp://dx.doi.org/10.13039/100004440
WT104033AIAWellcome Trusthttp://dx.doi.org/10.13039/100004440
165908Wellcome Trusthttp://dx.doi.org/10.13039/100004440
PubMed ID: 31820119
Go to PubMed abstract
URI: http://openaccess.sgul.ac.uk/id/eprint/111490
Publisher's version: https://doi.org/10.1007/s00401-019-02109-6

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