: The homologous genes GTPBP1 and GTPBP2 encode GTP-binding proteins 1 and 2, which are involved in ribosomal homeostasis. Pathogenic variants in GTPBP2 were recently shown to be an ultra-rare cause of neurodegenerative or neurodevelopmental disorders (NDDs). Until now, no human phenotype has been linked to GTPBP1. Here, we describe individuals carrying bi-allelic GTPBP1 variants that display an identical phenotype with GTPBP2 and characterize the overall spectrum of GTP-binding protein (1/2)-related disorders. In this study, 20 individuals from 16 families with distinct NDDs and syndromic facial features were investigated by whole-exome (WES) or whole-genome (WGS) sequencing. To assess the functional impact of the identified genetic variants, semi-quantitative PCR, western blot, and ribosome profiling assays were performed in fibroblasts from affected individuals. We also investigated the effect of reducing expression of CG2017, an ortholog of human GTPBP1/2, in the fruit fly Drosophila melanogaster. Individuals with bi-allelic GTPBP1 or GTPBP2 variants presented with microcephaly, profound neurodevelopmental impairment, pathognomonic craniofacial features, and ectodermal defects. Abnormal vision and/or hearing, progressive spasticity, choreoathetoid movements, refractory epilepsy, and brain atrophy were part of the core phenotype of this syndrome. Cell line studies identified a loss-of-function (LoF) impact of the disease-associated variants but no significant abnormalities on ribosome profiling. Reduced expression of CG2017 isoforms was associated with locomotor impairment in Drosophila. In conclusion, bi-allelic GTPBP1 and GTPBP2 LoF variants cause an identical, distinct neurodevelopmental syndrome. Mutant CG2017 knockout flies display motor impairment, highlighting the conserved role for GTP-binding proteins in CNS development across species.

Bi-allelic genetic variants in the translational GTPases GTPBP1 and GTPBP2 cause a distinct identical neurodevelopmental syndrome

Battini, Roberta
;
2023-01-01

Abstract

: The homologous genes GTPBP1 and GTPBP2 encode GTP-binding proteins 1 and 2, which are involved in ribosomal homeostasis. Pathogenic variants in GTPBP2 were recently shown to be an ultra-rare cause of neurodegenerative or neurodevelopmental disorders (NDDs). Until now, no human phenotype has been linked to GTPBP1. Here, we describe individuals carrying bi-allelic GTPBP1 variants that display an identical phenotype with GTPBP2 and characterize the overall spectrum of GTP-binding protein (1/2)-related disorders. In this study, 20 individuals from 16 families with distinct NDDs and syndromic facial features were investigated by whole-exome (WES) or whole-genome (WGS) sequencing. To assess the functional impact of the identified genetic variants, semi-quantitative PCR, western blot, and ribosome profiling assays were performed in fibroblasts from affected individuals. We also investigated the effect of reducing expression of CG2017, an ortholog of human GTPBP1/2, in the fruit fly Drosophila melanogaster. Individuals with bi-allelic GTPBP1 or GTPBP2 variants presented with microcephaly, profound neurodevelopmental impairment, pathognomonic craniofacial features, and ectodermal defects. Abnormal vision and/or hearing, progressive spasticity, choreoathetoid movements, refractory epilepsy, and brain atrophy were part of the core phenotype of this syndrome. Cell line studies identified a loss-of-function (LoF) impact of the disease-associated variants but no significant abnormalities on ribosome profiling. Reduced expression of CG2017 isoforms was associated with locomotor impairment in Drosophila. In conclusion, bi-allelic GTPBP1 and GTPBP2 LoF variants cause an identical, distinct neurodevelopmental syndrome. Mutant CG2017 knockout flies display motor impairment, highlighting the conserved role for GTP-binding proteins in CNS development across species.
2023
Salpietro, Vincenzo; Maroofian, Reza; Zaki, Maha S; Wangen, Jamie; Ciolfi, Andrea; Barresi, Sabina; Efthymiou, Stephanie; Lamaze, Angelique; Aughey, Gabriel N; Al Mutairi, Fuad; Rad, Aboulfazl; Rocca, Clarissa; Calì, Elisa; Accogli, Andrea; Zara, Federico; Striano, Pasquale; Mojarrad, Majid; Tariq, Huma; Giacopuzzi, Edoardo; Taylor, Jenny C; Oprea, Gabriela; Skrahina, Volha; Rehman, Khalil Ur; Abd Elmaksoud, Marwa; Bassiony, Mahmoud; El Said, Huda G; Abdel-Hamid, Mohamed S; Al Shalan, Maha; Seo, Gohun; Kim, Sohyun; Lee, Hane; Khang, Rin; Issa, Mahmoud Y; Elbendary, Hasnaa M; Rafat, Karima; Marinakis, Nikolaos M; Traeger-Synodinos, Joanne; Ververi, Athina; Sourmpi, Mara; Eslahi, Atieh; Khadivi Zand, Farhad; Beiraghi Toosi, Mehran; Babaei, Meisam; Jackson, Adam; Bertoli-Avella, Aida; Pagnamenta, Alistair T; Niceta, Marcello; Battini, Roberta; Corsello, Antonio; Leoni, Chiara; Chiarelli, Francesco; Dallapiccola, Bruno; Faqeih, Eissa Ali; Tallur, Krishnaraya K; Alfadhel, Majid; Alobeid, Eman; Maddirevula, Sateesh; Mankad, Kshitij; Banka, Siddharth; Ghayoor-Karimiani, Ehsan; Tartaglia, Marco; Chung, Wendy K; Green, Rachel; Alkuraya, Fowzan S; Jepson, James E C; Houlden, Henry
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/1217532
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