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Efthymiou S, Scala M, Nagaraj V, Ochenkowska K, Komdeur FL, Liang RA, Abdel-Hamid MS, Sultan T, Barøy T, Van Ghelue M, Vona B, Maroofian R, Zafar F, Alkuraya FS, Zaki MS, Severino M, Duru KC, Tryon RC, Brauteset LV, Ansari M, Hamilton M, van Haelst MM, van Haaften G, Zara F, Houlden H, Samarut É, Nichols CG, Smeland MF, McClenaghan C. Novel loss-of-function variants expand ABCC9-related intellectual disability and myopathy syndrome. Brain 2024; 147:1822-1836. [PMID: 38217872 PMCID: PMC11068106 DOI: 10.1093/brain/awae010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 11/22/2023] [Accepted: 12/30/2023] [Indexed: 01/15/2024] Open
Abstract
Loss-of-function mutation of ABCC9, the gene encoding the SUR2 subunit of ATP sensitive-potassium (KATP) channels, was recently associated with autosomal recessive ABCC9-related intellectual disability and myopathy syndrome (AIMS). Here we identify nine additional subjects, from seven unrelated families, harbouring different homozygous loss-of-function variants in ABCC9 and presenting with a conserved range of clinical features. All variants are predicted to result in severe truncations or in-frame deletions within SUR2, leading to the generation of non-functional SUR2-dependent KATP channels. Affected individuals show psychomotor delay and intellectual disability of variable severity, microcephaly, corpus callosum and white matter abnormalities, seizures, spasticity, short stature, muscle fatigability and weakness. Heterozygous parents do not show any conserved clinical pathology but report multiple incidences of intra-uterine fetal death, which were also observed in an eighth family included in this study. In vivo studies of abcc9 loss-of-function in zebrafish revealed an exacerbated motor response to pentylenetetrazole, a pro-convulsive drug, consistent with impaired neurodevelopment associated with an increased seizure susceptibility. Our findings define an ABCC9 loss-of-function-related phenotype, expanding the genotypic and phenotypic spectrum of AIMS and reveal novel human pathologies arising from KATP channel dysfunction.
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Affiliation(s)
- Stephanie Efthymiou
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Marcello Scala
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, 16147 Genoa, Italy
- U.O.C. Genetica Medica, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
| | - Vini Nagaraj
- Center for Advanced Biotechnology and Medicine, and Departments of Pharmacology and Medicine, Robert Wood Johnson Medical School, Rutgers the State University of New Jersey, Piscatway, NJ 08854, USA
| | - Katarzyna Ochenkowska
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), and Department of Neuroscience, Université de Montréal, Montreal H2X 0A9, Quebec, Canada
| | - Fenne L Komdeur
- Section Clinical Genetics, Department of Human Genetics and Amsterdam Reproduction and Development, Amsterdam University Medical Centers, 1105 AZ, Amsterdam, The Netherlands
| | - Robin A Liang
- Department of Medical Genetics, Division of Child and Adolescent Health, University Hospital of North Norway, 9019 Tromsø, Norway
| | - Mohamed S Abdel-Hamid
- Medical Molecular Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo 12622, Egypt
| | - Tipu Sultan
- Department of Pediatric Neurology, Children Hospital, University of Child Health Sciences, Lahore, Punjab 54000, Pakistan
| | - Tuva Barøy
- Department of Medical Genetics, Oslo University Hospital, 0450 Oslo, Norway
| | - Marijke Van Ghelue
- Department of Medical Genetics, Division of Child and Adolescent Health, University Hospital of North Norway, 9019 Tromsø, Norway
| | - Barbara Vona
- Institute of Human Genetics and Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37073 Göttingen, Germany
| | - Reza Maroofian
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Faisal Zafar
- Department of Paediatric Neurology, Children’s Hospital and Institute of Child Health, Multan, Punjab 60000, Pakistan
| | - Fowzan S Alkuraya
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh 12713, Saudi Arabia
| | - Maha S Zaki
- Clinical Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo 12622, Egypt
| | | | - Kingsley C Duru
- Center for Advanced Biotechnology and Medicine, and Departments of Pharmacology and Medicine, Robert Wood Johnson Medical School, Rutgers the State University of New Jersey, Piscatway, NJ 08854, USA
| | - Robert C Tryon
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO 63110, USA
| | - Lin Vigdis Brauteset
- Division of Habilitation for Children, Innlandet Hospital Sanderud, Hamar 2312, Norway
| | - Morad Ansari
- South East Scotland Genetic Service, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Mark Hamilton
- West of Scotland Clinical Genetics Service, Queen Elizabeth University Hospital, Glasgow G51 4TF, UK
| | - Mieke M van Haelst
- Section Clinical Genetics, Department of Human Genetics and Amsterdam Reproduction and Development, Amsterdam University Medical Centers, 1105 AZ, Amsterdam, The Netherlands
| | - Gijs van Haaften
- Department of Genetics, University Medical Center, Utrecht, 3584 CX, The Netherlands
| | - Federico Zara
- U.O.C. Genetica Medica, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
| | - Henry Houlden
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Éric Samarut
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), and Department of Neuroscience, Université de Montréal, Montreal H2X 0A9, Quebec, Canada
| | - Colin G Nichols
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO 63110, USA
| | - Marie F Smeland
- Department of Pediatric Rehabilitation, University Hospital of North Norway, 9019 Tromsø, Norway
- Institute of Clinical Medicine, UiT The Arctic University of Norway, 9019, Tromsø, Norway
| | - Conor McClenaghan
- Center for Advanced Biotechnology and Medicine, and Departments of Pharmacology and Medicine, Robert Wood Johnson Medical School, Rutgers the State University of New Jersey, Piscatway, NJ 08854, USA
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2
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Liénard C, Pintart A, Bomont P. Neuronal Autophagy: Regulations and Implications in Health and Disease. Cells 2024; 13:103. [PMID: 38201307 PMCID: PMC10778363 DOI: 10.3390/cells13010103] [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: 10/26/2023] [Revised: 12/02/2023] [Accepted: 12/27/2023] [Indexed: 01/12/2024] Open
Abstract
Autophagy is a major degradative pathway that plays a key role in sustaining cell homeostasis, integrity, and physiological functions. Macroautophagy, which ensures the clearance of cytoplasmic components engulfed in a double-membrane autophagosome that fuses with lysosomes, is orchestrated by a complex cascade of events. Autophagy has a particularly strong impact on the nervous system, and mutations in core components cause numerous neurological diseases. We first review the regulation of autophagy, from autophagosome biogenesis to lysosomal degradation and associated neurodevelopmental/neurodegenerative disorders. We then describe how this process is specifically regulated in the axon and in the somatodendritic compartment and how it is altered in diseases. In particular, we present the neuronal specificities of autophagy, with the spatial control of autophagosome biogenesis, the close relationship of maturation with axonal transport, and the regulation by synaptic activity. Finally, we discuss the physiological functions of autophagy in the nervous system, during development and in adulthood.
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Affiliation(s)
- Caroline Liénard
- NeuroMyoGene Institute—PGNM, CNRS UMR 5261—INSERM U1315, University of Claude Bernard Lyon 1, 69008 Lyon, France; (C.L.); (A.P.)
- CHU Montpellier, University of Montpellier, 34295 Montpellier, France
| | - Alexandre Pintart
- NeuroMyoGene Institute—PGNM, CNRS UMR 5261—INSERM U1315, University of Claude Bernard Lyon 1, 69008 Lyon, France; (C.L.); (A.P.)
| | - Pascale Bomont
- NeuroMyoGene Institute—PGNM, CNRS UMR 5261—INSERM U1315, University of Claude Bernard Lyon 1, 69008 Lyon, France; (C.L.); (A.P.)
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3
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Proikas-Cezanne T, Haas ML, Pastor-Maldonado CJ, Schüssele DS. Human WIPI β-propeller function in autophagy and neurodegeneration. FEBS Lett 2024; 598:127-139. [PMID: 38058212 DOI: 10.1002/1873-3468.14782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/10/2023] [Accepted: 11/10/2023] [Indexed: 12/08/2023]
Abstract
The four human WIPI β-propellers, WIPI1 through WIPI4, belong to the ancient PROPPIN family and fulfill scaffold functions in the control of autophagy. In this context, WIPI β-propellers function as PI3P effectors during autophagosome formation and loss of WIPI function negatively impacts autophagy and contributes to neurodegeneration. Of particular interest are mutations in WDR45, the human gene that encodes WIPI4. Sporadic WDR45 mutations are the cause of a rare human neurodegenerative disease called BPAN, hallmarked by high brain iron accumulation. Here, we discuss the current understanding of the functions of human WIPI β-propellers and address unanswered questions with a particular focus on the role of WIPI4 in autophagy and BPAN.
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Affiliation(s)
- Tassula Proikas-Cezanne
- Interfaculty Institute of Cell Biology, Department of Biology, Faculty of Science, Eberhard Karls University Tübingen, Germany
| | - Maximilian L Haas
- Interfaculty Institute of Cell Biology, Department of Biology, Faculty of Science, Eberhard Karls University Tübingen, Germany
| | - Carmen J Pastor-Maldonado
- Interfaculty Institute of Cell Biology, Department of Biology, Faculty of Science, Eberhard Karls University Tübingen, Germany
| | - David S Schüssele
- Interfaculty Institute of Cell Biology, Department of Biology, Faculty of Science, Eberhard Karls University Tübingen, Germany
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4
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Shimizu T, Tamura N, Nishimura T, Saito C, Yamamoto H, Mizushima N. Comprehensive analysis of autophagic functions of WIPI family proteins and their implications for the pathogenesis of β-propeller associated neurodegeneration. Hum Mol Genet 2023; 32:2623-2637. [PMID: 37364041 PMCID: PMC10407718 DOI: 10.1093/hmg/ddad096] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 05/15/2023] [Accepted: 06/13/2023] [Indexed: 06/28/2023] Open
Abstract
β-propellers that bind polyphosphoinositides (PROPPINs) are an autophagy-related protein family conserved throughout eukaryotes. The PROPPIN family includes Atg18, Atg21 and Hsv2 in yeast and WD-repeat protein interacting with phosphoinositides (WIPI)1-4 in mammals. Mutations in the WIPI genes are associated with human neuronal diseases, including β-propeller associated neurodegeneration (BPAN) caused by mutations in WDR45 (encoding WIPI4). In contrast to yeast PROPPINs, the functions of mammalian WIPI1-WIPI4 have not been systematically investigated. Although the involvement of WIPI2 in autophagy has been clearly shown, the functions of WIPI1, WIPI3 and WIPI4 in autophagy remain poorly understood. In this study, we comprehensively analyzed the roles of WIPI proteins by using WIPI-knockout (single, double and quadruple knockout) HEK293T cells and recently developed HaloTag-based reporters, which enable us to monitor autophagic flux sensitively and quantitatively. We found that WIPI2 was nearly essential for autophagy. Autophagic flux was unaffected or only slightly reduced by single deletion of WIPI3 (encoded by WDR45B) or WIPI4 but was profoundly reduced by double deletion of WIPI3 and WIPI4. Furthermore, we revealed variable effects of BPAN-related missense mutations on the autophagic activity of WIPI4. BPAN is characterized by neurodevelopmental and neurodegenerative abnormalities, and we found a possible association between the magnitude of the defect of the autophagic activity of WIPI4 mutants and the severity of neurodevelopmental symptoms. However, some of the BPAN-related missense mutations, which produce neurodegenerative signs, showed almost normal autophagic activity, suggesting that non-autophagic functions of WIPI4 may be related to neurodegeneration in BPAN.
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Affiliation(s)
- Takahiro Shimizu
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
| | - Norito Tamura
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
| | - Taki Nishimura
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
- PRESTO, Japan Science and Technology Agency, Tokyo 102-0076, Japan
| | - Chieko Saito
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
| | - Hayashi Yamamoto
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
- Department of Molecular Oncology, Nippon Medical School, Institute for Advanced Medical Sciences, Tokyo 113-8602, Japan
| | - Noboru Mizushima
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
- International Research Center for Neurointelligence (WPI-IRCN), UTIAS, The University of Tokyo, Tokyo 113-8655, Japan
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5
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Abstract
Macroautophagy and microautophagy are highly conserved eukaryotic cellular processes that degrade cytoplasmic material in lysosomes. Both pathways involve characteristic membrane dynamics regulated by autophagy-related proteins and other molecules, some of which are shared between the two pathways. Over the past few years, the application of new technologies, such as cryo-electron microscopy, coevolution-based structural prediction and in vitro reconstitution, has revealed the functions of individual autophagy gene products, especially in autophagy induction, membrane reorganization and cargo recognition. Concomitantly, mutations in autophagy genes have been linked to human disorders, particularly neurodegenerative diseases, emphasizing the potential pathogenic implications of autophagy defects. Accumulating genome data have also illuminated the evolution of autophagy genes within eukaryotes as well as their transition from possible ancestral elements in prokaryotes.
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Affiliation(s)
- Hayashi Yamamoto
- grid.26999.3d0000 0001 2151 536XDepartment of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan ,grid.410821.e0000 0001 2173 8328Department of Molecular Oncology, Institute for Advanced Medical Sciences, Nippon Medical School, Tokyo, Japan
| | - Sidi Zhang
- grid.26999.3d0000 0001 2151 536XDepartment of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Noboru Mizushima
- grid.26999.3d0000 0001 2151 536XDepartment of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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6
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Papandreou A, Soo AKS, Spaull R, Mankad K, Kurian MA, Sudhakar S. Expanding the Spectrum of Early Neuroradiologic Findings in β Propeller Protein-Associated Neurodegeneration. AJNR Am J Neuroradiol 2022; 43:1810-1814. [PMID: 36328404 DOI: 10.3174/ajnr.a7693] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 10/01/2022] [Indexed: 11/06/2022]
Abstract
BACKGROUND AND PURPOSE β propeller protein-associated neurodegeneration (BPAN) is the most common neurodegeneration with brain iron accumulation disorder. Typical radiologic findings are T2 hypointensity in the substantia nigra and globus pallidus, as well as a T1 halolike substantia nigra hyperintense signal surrounding a hypointense central area. However, these findings are often subtle or absent on initial scans, risking diagnostic delay. In this study, we sought to investigate radiologic findings that could aid in the early diagnosis of BPAN. MATERIALS AND METHODS A retrospective cohort study was performed in a national referral center, including all pediatric patients with confirmed pathogenic WDR45 mutations and consistent clinical semiology. MR imaging findings were independently reported by 2 pediatric neuroradiologists. RESULTS Fifteen patients were included in the study, and 27 scans were available for review. The initial neuroimaging study was undertaken at a mean age of 3.2 years. Iron deposition was uncommon in patients younger than 4 years of age. Neuroradiologic features from very early on included dentate, globus pallidus, and substantia nigra swelling, as well as a thin corpus callosum and small pontine volume. Optic nerve thinning was also present in all patients. CONCLUSIONS Our study highlights the key early MR imaging features of BPAN. Iron deposition in the globus pallidus and substantia nigra is not common in children younger than 4 years of age; clinicians should not be deterred from suspecting BPAN in the presence of the findings described in this study and the appropriate clinical context.
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Affiliation(s)
- A Papandreou
- From the Molecular Neurosciences (A.P., A.K.S.S., R.S., M.A.K.), Developmental Neurosciences Programme, Zayed Centre for Research into Rare Disease in Children, University College London Great Ormond Street Institute of Child Health, London, UK .,Departments of Neurology (A.P., A.K.S.S., R.S., M.A.K.)
| | - A K S Soo
- From the Molecular Neurosciences (A.P., A.K.S.S., R.S., M.A.K.), Developmental Neurosciences Programme, Zayed Centre for Research into Rare Disease in Children, University College London Great Ormond Street Institute of Child Health, London, UK.,Departments of Neurology (A.P., A.K.S.S., R.S., M.A.K.)
| | - R Spaull
- From the Molecular Neurosciences (A.P., A.K.S.S., R.S., M.A.K.), Developmental Neurosciences Programme, Zayed Centre for Research into Rare Disease in Children, University College London Great Ormond Street Institute of Child Health, London, UK.,Departments of Neurology (A.P., A.K.S.S., R.S., M.A.K.)
| | - K Mankad
- Neuroradiology (K.M., S.S.), Great Ormond Street Hospital for Children National Health Service Foundation Trust, London, UK
| | - M A Kurian
- From the Molecular Neurosciences (A.P., A.K.S.S., R.S., M.A.K.), Developmental Neurosciences Programme, Zayed Centre for Research into Rare Disease in Children, University College London Great Ormond Street Institute of Child Health, London, UK.,Departments of Neurology (A.P., A.K.S.S., R.S., M.A.K.)
| | - S Sudhakar
- Neuroradiology (K.M., S.S.), Great Ormond Street Hospital for Children National Health Service Foundation Trust, London, UK
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7
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Chiapparini L, Zorzi G. Early Neuroimaging Markers in β Propeller Protein-Associated Neurodegeneration. AJNR Am J Neuroradiol 2022; 43:1815-1816. [PMID: 36396333 DOI: 10.3174/ajnr.a7723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
| | - G Zorzi
- Department of Paediatric Neuroscience Fondazione Institute for Hospitalization and Healthcare Istituto Neurologico Carlo Besta Milan, Italy
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8
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Almannai M, Marafi D, El-Hattab AW. WIPI proteins: Biological functions and related syndromes. Front Mol Neurosci 2022; 15:1011918. [PMID: 36157071 PMCID: PMC9500159 DOI: 10.3389/fnmol.2022.1011918] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 08/10/2022] [Indexed: 11/13/2022] Open
Abstract
WIPI (WD-repeat protein Interacting with PhosphoInositides) are important effectors in autophagy. These proteins bind phosphoinositides and recruit autophagy proteins. In mammals, there are four WIPI proteins: WIPI1, WIPI2, WIPI3 (WDR45B), and WIPI4 (WDR45). These proteins consist of a seven-bladed β-propeller structure. Recently, pathogenic variants in genes encoding these proteins have been recognized to cause human diseases with a predominant neurological phenotype. Defects in WIPI2 cause a disease characterized mainly by intellectual disability and variable other features while pathogenic variants in WDR45B and WDR45 have been recently reported to cause El-Hattab-Alkuraya syndrome and beta-propeller protein-associated neurodegeneration (BPAN), respectively. Whereas, there is no disease linked to WIPI1 yet, one study linked it neural tube defects (NTD). In this review, the role of WIPI proteins in autophagy is discussed first, then syndromes related to these proteins are summarized.
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Affiliation(s)
- Mohammed Almannai
- Genetics and Precision Medicine Department, King Abdullah Specialized Children's Hospital, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
- *Correspondence: Mohammed Almannai
| | - Dana Marafi
- Department of Pediatrics, Faculty of Medicine, Kuwait University, Jabriya, Kuwait
| | - Ayman W. El-Hattab
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates
- Department of Pediatrics, University Hospital Sharjah, Sharjah, United Arab Emirates
- Genetics and Metabolic Department, KidsHeart Medical Center, Abu Dhabi, United Arab Emirates
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9
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Dafsari HS, Pemberton JG, Ferrer EA, Yammine T, Farra C, Mohammadi MH, Ghayoor Karimiani E, Hashemi N, Souaid M, Sabbagh S, Najarzadeh Torbati P, Khan S, Roze E, Moreno‐De‐Luca A, Bertoli‐Avella AM, Houlden H, Balla T, Maroofian R. PI4K2A deficiency causes innate error in intracellular trafficking with developmental and epileptic-dyskinetic encephalopathy. Ann Clin Transl Neurol 2022; 9:1345-1358. [PMID: 35880319 PMCID: PMC9463957 DOI: 10.1002/acn3.51634] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 07/07/2022] [Accepted: 07/08/2022] [Indexed: 01/26/2023] Open
Abstract
OBJECTIVE Intracellular signaling networks rely on proper membrane organization to control an array of cellular processes such as metabolism, proliferation, apoptosis, and macroautophagy in eukaryotic cells and organisms. Phosphatidylinositol 4-phosphate (PI4P) emerged as an essential regulatory lipid within organelle membranes that defines their lipid composition and signaling properties. PI4P is generated by four distinct phosphatidylinositol 4-kinases (PI4K) in mammalian cells: PI4KA, PI4KB, PI4K2A, PI4K2B. Animal models and human genetic studies suggest vital roles of PI4K enzymes in development and function of various organs, including the nervous system. Bi-allelic variants in PI4KA were recently associated with neurodevelopmental disorders (NDD), brain malformations, leukodystrophy, primary immunodeficiency, and inflammatory bowel disease. Here, we describe patients from two unrelated consanguineous families with PI4K2A deficiency and functionally explored the pathogenic mechanism. METHODS Two patients with PI4K2A deficiency were identified by exome sequencing, presenting with developmental and epileptic-dyskinetic encephalopathy. Neuroimaging showed corpus callosum dysgenesis, diffuse white matter volume loss, and hypoplastic vermis. In addition to NDD, we observed recurrent infections and death at toddler age. We further explored identified variants with cellular assays. RESULTS This clinical presentation overlaps with what was previously reported in two affected siblings with homozygous nonsense PI4K2A variant. Cellular studies analyzing these human variants confirmed their deleterious effect on PI4K2A activity and, together with the central role of PI4K2A in Rab7-associated vesicular trafficking, establish a link between late endosome-lysosome defects and NDD. INTERPRETATION Our study establishes the genotype-phenotype spectrum of PI4K-associated NDD and highlights several commonalities with other innate errors of intracellular trafficking.
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Affiliation(s)
- Hormos Salimi Dafsari
- Department of PediatricsFaculty of Medicine and University Hospital Cologne, University of CologneKerpener Str. 6250937KölnGermany,Max‐Planck‐Institute for Biology of Ageing and CECADCologneGermany,Evelina Children's Hospital, Guy's & St Thomas' NHS Foundation TrustLondonUK
| | - Joshua G. Pemberton
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver NICHDNational Institutes of HealthBethesdaMarylandUSA
| | - Elizabeth A. Ferrer
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver NICHDNational Institutes of HealthBethesdaMarylandUSA
| | - Tony Yammine
- Medical Genetics UnitSaint Joseph UniversityBeirutLebanon
| | - Chantal Farra
- Medical Genetics UnitSaint Joseph UniversityBeirutLebanon,Department of GeneticsHotel Dieu de France Medical CenterBeirutLebanon
| | | | - Ehsan Ghayoor Karimiani
- Molecular and Clinical Sciences InstituteSt. George's, University of LondonCranmer TerraceLondonUK,Department of Medical GeneticsNext Generation Genetic PolyclinicMashhadIran
| | - Narges Hashemi
- Department of Pediatric Neurology, Faculty of MedicineMashhad University of Medical SciencesMashhadIran
| | - Mirna Souaid
- Medical Genetics UnitSaint Joseph UniversityBeirutLebanon
| | - Sandra Sabbagh
- Department of GeneticsHotel Dieu de France Medical CenterBeirutLebanon
| | | | | | - Emmanuel Roze
- CNRS, INSERM, Institut du Cerveau (ICM)Sorbonne UniversitéParis75013France,DMU NeurosciencesHôpital de la Pitié‐Salpêtrière, Assistance Publique‐Hôpitaux de ParisParis75013France
| | - Andres Moreno‐De‐Luca
- Department of Radiology, Diagnostic Medicine InstituteAutism & Developmental Medicine Institute, Genomic Medicine Institute, GeisingerDanvillePennsylvaniaUSA
| | | | - Henry Houlden
- Department of Neuromuscular DiseasesUCL Queen Square Institute of NeurologyQueen SquareLondonUK
| | - Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver NICHDNational Institutes of HealthBethesdaMarylandUSA
| | - Reza Maroofian
- Department of Neuromuscular DiseasesUCL Queen Square Institute of NeurologyQueen SquareLondonUK
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10
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Genetic disorders of cellular trafficking. Trends Genet 2022; 38:724-751. [DOI: 10.1016/j.tig.2022.02.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 02/11/2022] [Accepted: 02/28/2022] [Indexed: 02/06/2023]
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