1
|
Aughey G, Cali E, Maroofian R, Zaki MS, Pagnamenta AT, Rahman F, Menzies L, Shafique A, Suri M, Roze E, Aguennouz M, Ghizlane Z, Saadi SM, Ali Z, Abdulllah U, Cheema HA, Anjum MN, Morel G, McFarland R, Altunoglu U, Kraus V, Shoukier M, Murphy D, Flemming K, Yttervik H, Rhouda H, Lesca G, Murtaza BN, Rehman MU, Consortium GE, Seo GH, Beetz C, Kayserili H, Krioulie Y, Chung WK, Naz S, Maqbool S, Gleeson J, Baig SM, Efthymiou S, Taylor JC, Severino M, Jepson JE, Houlden H. Clinical and neurogenetic characterisation of autosomal recessive RBL2-associated progressive neurodevelopmental disorder. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.05.03.24306631. [PMID: 38746364 PMCID: PMC11092723 DOI: 10.1101/2024.05.03.24306631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Retinoblastoma (RB) proteins are highly conserved transcriptional regulators that play important roles during development by regulating cell-cycle gene expression. RBL2 dysfunction has been linked to a severe neurodevelopmental disorder. However, to date, clinical features have only been described in six individuals carrying five biallelic predicted loss of function (pLOF) variants. To define the phenotypic effects of RBL2 mutations in detail, we identified and clinically characterized a cohort of 28 patients from 18 families carrying LOF variants in RBL2 , including fourteen new variants that substantially broaden the molecular spectrum. The clinical presentation of affected individuals is characterized by a range of neurological and developmental abnormalities. Global developmental delay and intellectual disability were uniformly observed, ranging from moderate to profound and involving lack of acquisition of key motor and speech milestones in most patients. Frequent features included postnatal microcephaly, infantile hypotonia, aggressive behaviour, stereotypic movements and non-specific dysmorphic features. Common neuroimaging features were cerebral atrophy, white matter volume loss, corpus callosum hypoplasia and cerebellar atrophy. In parallel, we used the fruit fly, Drosophila melanogaster , to investigate how disruption of the conserved RBL2 orthologueue Rbf impacts nervous system function and development. We found that Drosophila Rbf LOF mutants recapitulate several features of patients harboring RBL2 variants, including alterations in the head and brain morphology reminiscent of microcephaly, and perturbed locomotor behaviour. Surprisingly, in addition to its known role in controlling tissue growth during development, we find that continued Rbf expression is also required in fully differentiated post-mitotic neurons for normal locomotion in Drosophila , and that adult-stage neuronal re-expression of Rbf is sufficient to rescue Rbf mutant locomotor defects. Taken together, this study provides a clinical and experimental basis to understand genotype-phenotype correlations in an RBL2 -linked neurodevelopmental disorder and suggests that restoring RBL2 expression through gene therapy approaches may ameliorate aspects of RBL2 LOF patient symptoms.
Collapse
|
2
|
Samra N, Jansen NS, Morani I, Kakun RR, Zaid R, Paperna T, Garcia-Dominguez M, Viner Y, Frankenthal H, Shinwell ES, Portnov I, Bakry D, Shalata A, Shapira Rootman M, Kidron D, Claessens LA, Wevers RA, Mandel H, Vertegaal ACO, Weiss K. Exome sequencing links the SUMO protease SENP7 with fatal arthrogryposis multiplex congenita, early respiratory failure and neutropenia. J Med Genet 2023; 60:1133-1141. [PMID: 37460201 DOI: 10.1136/jmg-2023-109267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 06/08/2023] [Indexed: 10/26/2023]
Abstract
BACKGROUND SUMOylation involves the attachment of small ubiquitin-like modifier (SUMO) proteins to specific lysine residues on thousands of substrates with target-specific effects on protein function. Sentrin-specific proteases (SENPs) are proteins involved in the maturation and deconjugation of SUMO. Specifically, SENP7 is responsible for processing polySUMO chains on targeted substrates including the heterochromatin protein 1α (HP1α). METHODS We performed exome sequencing and segregation studies in a family with several infants presenting with an unidentified syndrome. RNA and protein expression studies were performed in fibroblasts available from one subject. RESULTS We identified a kindred with four affected subjects presenting with a spectrum of findings including congenital arthrogryposis, no achievement of developmental milestones, early respiratory failure, neutropenia and recurrent infections. All died within four months after birth. Exome sequencing identified a homozygous stop gain variant in SENP7 c.1474C>T; p.(Gln492*) as the probable aetiology. The proband's fibroblasts demonstrated decreased mRNA expression. Protein expression studies showed significant protein dysregulation in total cell lysates and in the chromatin fraction. We found that HP1α levels as well as different histones and H3K9me3 were reduced in patient fibroblasts. These results support previous studies showing interaction between SENP7 and HP1α, and suggest loss of SENP7 leads to reduced heterochromatin condensation and subsequent aberrant gene expression. CONCLUSION Our results suggest a critical role for SENP7 in nervous system development, haematopoiesis and immune function in humans.
Collapse
Affiliation(s)
- Nadra Samra
- Department of Genetics, Ziv Medical Center, Safed, Israel
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Nicolette S Jansen
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Ilham Morani
- Department of Genetics, Ziv Medical Center, Safed, Israel
| | - Reli Rachel Kakun
- The Clinical Research Institute, Rambam Health Care Campus, Haifa, Israel
| | - Rinat Zaid
- The Genetics Institute, Rambam Health Care Campus, Haifa, Israel
| | - Tamar Paperna
- The Genetics Institute, Rambam Health Care Campus, Haifa, Israel
| | - Mario Garcia-Dominguez
- Andalusian Centre for Molecular Biology and Regenerative Medicine-CABIMER, CSIC-Universidad Pablo de Olavide, Sevilla, Spain
| | - Yuri Viner
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
- Pediatric Intensive Care Unit, Ziv Medical Center, Safed, Israel
| | - Hilel Frankenthal
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
- Pediatric Intensive Care Unit, Ziv Medical Center, Safed, Israel
| | - Eric S Shinwell
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
- Department of Neonatology, Ziv Medical Center, Safed, Israel
| | - Igor Portnov
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
- Department of Neonatology, Ziv Medical Center, Safed, Israel
| | - Doua Bakry
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
- Department of Pediatric Hematology, Ziv Medical Center, Safed, Israel
| | - Adel Shalata
- Simon Winter Institute for Human Genetics, Bnai Zion Medical Center, Haifa, Israel
| | | | - Dvora Kidron
- Department of Pathology, Meir Medical Center, Kfar Saba, Israel
| | - Laura A Claessens
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Ron A Wevers
- Translational Metabolic Laboratory, Department Laboratory Medicine, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Hanna Mandel
- Metabolic unit, Ziv Medical Center, Safed, Israel
| | - Alfred C O Vertegaal
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Karin Weiss
- The Genetics Institute, Rambam Health Care Campus, Haifa, Israel
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| |
Collapse
|
3
|
Rips J, Abu-Libdeh B, Koplewitz BZ, Kehat-Ophir S, Frenkel S, Elpeleg O, Harel T. Orbital nodular fasciitis in child with biallelic germline RBL2 variant. Eur J Med Genet 2022; 65:104513. [PMID: 35487417 DOI: 10.1016/j.ejmg.2022.104513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 04/23/2022] [Indexed: 11/17/2022]
Abstract
RBL2/p130 is one of three highly conserved members of the retinoblastoma (RB) protein family. It is strongly upregulated during neuronal differentiation and brain development, and is critical for survival of post-mitotic neurons. Similar to RB1, it has been implicated as a tumor suppressor gene and has been shown to be dysregulated in various types of cancer. Recent publications describe biallelic, germline loss of function variants in RBL2 in individuals with profound developmental delay. We report a child with profound developmental delay, microcephaly, and hypotonia, who developed fulminant exophthalmos at age 6 years. Brain MRI followed by a biopsy of an intra-orbital mass revealed a mesenchymal tumor. Post-surgical histopathologic examination of the resected tumor was compatible with diagnosis of nodular fasciitis. Exome sequencing from peripheral blood identified a biallelic frameshift variant (c.901dupT) in RBL2. Notably, no malignancies were reported in previous cases with RBL2 variants. This case provides a possible association between RBL2 and orbital tumors.
Collapse
Affiliation(s)
- Jonathan Rips
- Department of Genetics, Hadassah Medical Organization, Jerusalem, Israel
| | - Bassam Abu-Libdeh
- Department of Pediatrics & Genetics, Makassed Hospital, Al-Quds Medical School, E. Jerusalem, Palestine
| | - Benjamin Z Koplewitz
- Department of Radiology, Hadassah Medical Organization, Jerusalem, Israel; Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Shay Kehat-Ophir
- Division of Ophthalmology, Hadassah Medical Organization, Jerusalem, Israel
| | - Shahar Frenkel
- Division of Ophthalmology, Hadassah Medical Organization, Jerusalem, Israel; Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Orly Elpeleg
- Department of Genetics, Hadassah Medical Organization, Jerusalem, Israel; Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Tamar Harel
- Department of Genetics, Hadassah Medical Organization, Jerusalem, Israel; Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel.
| |
Collapse
|