TMEM161B modulates radial glial scaffolding in neocortical development
Wang L, Heffner C, Vong KL, Barrows C, Ha YJ, Lee S, Lara-Gonzalez P, Jhamb I, Van Der Meer D, Loughnan R, Parker N, Sievert D, Mittal S, Issa MY, Andreassen OA, Dale A, Dobyns WB, Zaki MS, Murray SA, Gleeson JG.
Proc Natl Acad Sci U S A. 2023 Jan 24;120(4):e2209983120. doi: 10.1073/pnas.2209983120. Epub 2023 Jan 20.
TMEM161B encodes an evolutionarily conserved widely expressed novel 8-pass transmembrane protein of unknown function in human. Here we identify TMEM161B homozygous hypomorphic missense variants in our recessive polymicrogyria (PMG) cohort. Patients carrying TMEM161B mutations exhibit striking neocortical PMG and intellectual disability. Tmem161b knockout mice fail to develop midline hemispheric cleavage, whereas knock-in of patient mutations and patient-derived brain organoids show defects in apical cell polarity and radial glial scaffolding. We found that TMEM161B modulates actin filopodia, functioning upstream of the Rho-GTPase CDC42. Our data link TMEM161B with human PMG, likely regulating radial glia apical polarity during neocortical development.
January 24, 2023
Stem Cell-Based Organoid Models of Neurodevelopmental Disorders
Wang L, Owusu-Hammond C, Sievert D, Gleeson JG.
Biol Psychiatry. 2023 Jan 24:S0006-3223(23)00039-2. doi: 10.1016/j.biopsych.2023.01.012. Online ahead of print.
The past decade has seen an explosion in the identification of genetic causes of neurodevelopmental disorders, including Mendelian, de novo, and somatic factors. These discoveries provide opportunities to understand cellular and molecular mechanisms as well as potential gene-gene and gene-environment interactions to support novel therapies. Stem cell-based models, particularly human brain organoids, can capture disease-associated alleles in the context of the human genome, engineered to mirror disease-relevant aspects of cellular complexity and developmental timing. These models have brought key insights into neurodevelopmental disorders as diverse as microcephaly, autism, and focal epilepsy. However, intrinsic organoid-to-organoid variability, low levels of certain brain-resident cell types, and long culture times required to reach maturity can impede progress. Several recent advances incorporate specific morphogen gradients, mixtures of diverse brain cell types, and organoid engraftment into animal models. Together with nonhuman primate organoid comparisons, mechanisms of human neurodevelopmental disorders are emerging.
January 24, 2023
Comprehensive multi-omic profiling of somatic mutations in malformations of cortical development
Chung C, Yang X, Bae T, Vong KI, Mittal S, Donkels C, Westley Phillips H, Li Z, Marsh APL, Breuss MW, Ball LL, Garcia CAB, George RD, Gu J, Xu M, Barrows C, James KN, Stanley V, Nidhiry AS, Khoury S, Howe G, Riley E, Xu X, Copeland B, Wang Y, Kim SH, Kang HC, Schulze-Bonhage A, Haas CA, Urbach H, Prinz M, Limbrick DD Jr, Gurnett CA, Smyth MD, Sattar S, Nespeca M, Gonda DD, Imai K, Takahashi Y, Chen HH, Tsai JW, Conti V, Guerrini R, Devinsky O, Silva WA Jr, Machado HR, Mathern GW, Abyzov A, Baldassari S, Baulac S; Focal Cortical Dysplasia Neurogenetics Consortium; Brain Somatic Mosaicism Network; Gleeson JG.
Nat Genet. 2023 Jan 12. doi: 10.1038/s41588-022-01276-9. Online ahead of print.
Malformations of cortical development (MCD) are neurological conditions involving focal disruptions of cortical architecture and cellular organization that arise during embryogenesis, largely from somatic mosaic mutations, and cause intractable epilepsy. Identifying the genetic causes of MCD has been a challenge, as mutations remain at low allelic fractions in brain tissue resected to treat condition-related epilepsy. Here we report a genetic landscape from 283 brain resections, identifying 69 mutated genes through intensive profiling of somatic mutations, combining whole-exome and targeted-amplicon sequencing with functional validation including in utero electroporation of mice and single-nucleus RNA sequencing. Genotype-phenotype correlation analysis elucidated specific MCD gene sets associated with distinct pathophysiological and clinical phenotypes. The unique single-cell level spatiotemporal expression patterns of mutated genes in control and patient brains indicate critical roles in excitatory neurogenic pools during brain development and in promoting neuronal hyperexcitability after birth.
January 12, 2023
Control-independent mosaic single nucleotide variant detection with DeepMosaic
Yang X, Xu X, Breuss MW, Antaki D, Ball LL, Chung C, Shen J, Li C, George RD, Wang Y, Bae T, Cheng Y, Abyzov A, Wei L, Alexandrov LB, Sebat JL; NIMH Brain Somatic Mosaicism Network; Gleeson JG.
Nat Biotechnol. 2023 Jan 2. doi: 10.1038/s41587-022-01559-w. Online ahead of print.
Mosaic variants (MVs) reflect mutagenic processes during embryonic development and environmental exposure, accumulate with aging and underlie diseases such as cancer and autism. The detection of noncancer MVs has been computationally challenging due to the sparse representation of nonclonally expanded MVs. Here we present DeepMosaic, combining an image-based visualization module for single nucleotide MVs and a convolutional neural network-based classification module for control-independent MV detection. DeepMosaic was trained on 180,000 simulated or experimentally assessed MVs, and was benchmarked on 619,740 simulated MVs and 530 independent biologically tested MVs from 16 genomes and 181 exomes. DeepMosaic achieved higher accuracy compared with existing methods on biological data, with a sensitivity of 0.78, specificity of 0.83 and positive predictive value of 0.96 on noncancer whole-genome sequencing data, as well as doubling the validation rate over previous best-practice methods on noncancer whole-exome sequencing data (0.43 versus 0.18). DeepMosaic represents an accurate MV classifier for noncancer samples that can be implemented as an alternative or complement to existing methods.
January 2, 2023
Functional and clinical studies reveal pathophysiological complexity of CLCN4-related neurodevelopmental condition
Palmer EE, Pusch M, Picollo A, Forwood C, Nguyen MH, Suckow V, Gibbons J, Hoff A, Sigfrid L, Megarbane A, Nizon M, Cogné B, Beneteau C, Alkuraya FS, Chedrawi A, Hashem MO, Stamberger H, Weckhuysen S, Vanlander A, Ceulemans B, Rajagopalan S, Nunn K, Arpin S, Raynaud M, Motter CS, Ward-Melver C, Janssens K, Meuwissen M, Beysen D, Dikow N, Grimmel M, Haack TB, Clement E, McTague A, Hunt D, Townshend S, Ward M, Richards LJ, Simons C, Costain G, Dupuis L, Mendoza-Londono R, Dudding-Byth T, Boyle J, Saunders C, Fleming E, El Chehadeh S, Spitz MA, Piton A, Gerard B, Abi Warde MT, Rea G, McKenna C, Douzgou S, Banka S, Akman C, Bain JM, Sands TT, Wilson GN, Silvertooth EJ, Miller L, Lederer D, Sachdev R, Macintosh R, Monestier O, Karadurmus D, Collins F, Carter M, Rohena L, Willemsen MH, Ockeloen CW, Pfundt R, Kroft SD, Field M, Laranjeira FER, Fortuna AM, Soares AR, Michaud V, Naudion S, Golla S, Weaver DD, Bird LM, Friedman J, Clowes V, Joss S, Pölsler L, Campeau PM, Blazo M, Bijlsma EK, Rosenfeld JA, Beetz C, Powis Z, McWalter K, Brandt T, Torti E, Mathot M, Mohammad SS, Armstrong R, Kalscheuer VM.
Mol Psychiatry. 2022 Nov 16. doi: 10.1038/s41380-022-01852-9. Online ahead of print.
Missense and truncating variants in the X-chromosome-linked CLCN4 gene, resulting in reduced or complete loss-of-function (LOF) of the encoded chloride/proton exchanger ClC-4, were recently demonstrated to cause a neurocognitive phenotype in both males and females. Through international clinical matchmaking and interrogation of public variant databases we assembled a database of 90 rare CLCN4 missense variants in 90 families: 41 unique and 18 recurrent variants in 49 families. For 43 families, including 22 males and 33 females, we collated detailed clinical and segregation data. To confirm causality of variants and to obtain insight into disease mechanisms, we investigated the effect on electrophysiological properties of 59 of the variants in Xenopus oocytes using extended voltage and pH ranges. Detailed analyses revealed new pathophysiological mechanisms: 25% (15/59) of variants demonstrated LOF, characterized by a “shift” of the voltage-dependent activation to more positive voltages, and nine variants resulted in a toxic gain-of-function, associated with a disrupted gate allowing inward transport at negative voltages. Functional results were not always in line with in silico pathogenicity scores, highlighting the complexity of pathogenicity assessment for accurate genetic counselling. The complex neurocognitive and psychiatric manifestations of this condition, and hitherto under-recognized impacts on growth, gastrointestinal function, and motor control are discussed. Including published cases, we summarize features in 122 individuals from 67 families with CLCN4-related neurodevelopmental condition and suggest future research directions with the aim of improving the integrated care for individuals with this diagnosis.
November 16, 2022
Genetic Neurologic DiseaseNeurogenomics
Evaluating human mutation databases for “treatability” using patient-customized therapy
Mittal S, Tang I, Gleeson JG. Evaluating human mutation databases for “treatability” using patient-customized therapy. Med (N Y).
Med (N Y). 2022 Nov 11;3(11):740-759. doi: 10.1016/j.medj.2022.08.006.
Genome sequencing in the clinic often allows patients to receive a molecular diagnosis. However, variants are most often evaluated for pathogenicity, neglecting potential treatability and thus often yielding limited clinical benefit. Antisense oligonucleotides (ASOs), among others, offer attractive programmable and relatively safe platforms for customized therapy based upon the causative genetic variant. The landscape of ASO-treatable variants is largely uncharted, with new developments emerging for loss-of-function, haploinsufficient, and gain-of-function effects. ASOs can access the transcriptome to target splice-gain variants, poison exons, untranslated/regulatory regions, and naturally occurring antisense transcripts. Here we assess public variant databases and find that approximately half of pathogenic variants have one or more viable avenues for ASO therapy. The future might see medical teams considering “treatability” when interpreting genomic sequencing results to fully realize benefits for patients.
November 11, 2022
Brain monoamine vesicular transport disease caused by homozygous SLC18A2 variants: A study in 42 affected individuals
Saida K, Maroofian R, Sengoku T, Mitani T, Pagnamenta AT, Marafi D, Zaki MS, O’Brien TJ, Karimiani EG, Kaiyrzhanov R, Takizawa M, Ohori S, Leong HY, Akay G, Galehdari H, Zamani M, Romy R, Carroll CJ, Toosi MB, Ashrafzadeh F, Imannezhad S, Malek H, Ahangari N, Tomoum H, Gowda VK, Srinivasan VM, Murphy D, Dominik N, Elbendary HM, Rafat K, Yilmaz S, Kanmaz S, Serin M, Krishnakumar D, Gardham A, Maw A, Rao TS, Alsubhi S, Srour M, Buhas D, Jewett T, Goldberg RE, Shamseldin H, Frengen E, Misceo D, Strømme P, Magliocco Ceroni JR, Kim CA, Yesil G, Sengenc E, Guler S, Hull M, Parnes M, Aktas D, Anlar B, Bayram Y, Pehlivan D, Posey JE, Alavi S, Madani Manshadi SA, Alzaidan H, Al-Owain M, Alabdi L, Abdulwahab F, Sekiguchi F, Hamanaka K, Fujita A, Uchiyama Y, Mizuguchi T, Miyatake S, Miyake N, Elshafie RM, Salayev K, Guliyeva U, Alkuraya FS, Gleeson JG, Monaghan KG, Langley KG, Yang H, Motavaf M, Safari S, Alipour M, Ogata K, Brown AEX, Lupski JR, Houlden H, Matsumoto N.
Genet Med. 2022 Oct 31:S1098-3600(22)00948-0. doi: 10.1016/j.gim.2022.09.010. Online ahead of print.
PURPOSE: Brain monoamine vesicular transport disease is an infantile-onset movement disorder that mimics cerebral palsy. In 2013, the homozygous SLC18A2 variant, p.Pro387Leu, was first reported as a cause of this rare disorder, and dopamine agonists were efficient for treating affected individuals from a single large family. To date, only 6 variants have been reported. In this study, we evaluated genotype-phenotype correlations in individuals with biallelic SLC18A2 variants.
METHODS: A total of 42 affected individuals with homozygous SLC18A2 variant alleles were identified. We evaluated genotype-phenotype correlations and the missense variants in the affected individuals based on the structural modeling of rat VMAT2 encoded by Slc18a2, with cytoplasm- and lumen-facing conformations. A Caenorhabditis elegans model was created for functional studies.
RESULTS: A total of 19 homozygous SLC18A2 variants, including 3 recurrent variants, were identified using exome sequencing. The affected individuals typically showed global developmental delay, hypotonia, dystonia, oculogyric crisis, and autonomic nervous system involvement (temperature dysregulation/sweating, hypersalivation, and gastrointestinal dysmotility). Among the 58 affected individuals described to date, 16 (28%) died before the age of 13 years. Of the 17 patients with p.Pro237His, 9 died, whereas all 14 patients with p.Pro387Leu survived. Although a dopamine agonist mildly improved the disease symptoms in 18 of 21 patients (86%), some affected individuals with p.Ile43Phe and p.Pro387Leu showed milder phenotypes and presented prolonged survival even without treatment. The C. elegans model showed behavioral abnormalities.
CONCLUSION: These data expand the phenotypic and genotypic spectra of SLC18A2-related disorders.
October 31, 2022
Phenotypic continuum of NFU1-related disorders
Kaiyrzhanov R, Zaki MS, Lau T, Sen S, Azizimalamiri R, Zamani M, Sayin GY, Hilander T, Efthymiou S, Chelban V, Brown R, Thompson K, Scarano MI, Ganesh J, Koneev K, Gülaçar IM, Person R, Sadykova D, Maidyrov Y, Seifi T, Zadagali A, Bernard G, Allis K, Elloumi HZ, Lindy A, Taghiabadi E, Verma S, Logan R, Kirmse B, Bai R, Khalaf SM, Abdel-Hamid MS, Sedaghat A, Shariati G, Issa M, Zeighami J, Elbendary HM, Brown G, Taylor RW, Galehdari H, Gleeson JJ, Carroll CJ, Cowan JA, Moreno-De-Luca A, Houlden H, Maroofian R.
Ann Clin Transl Neurol. 2022 Oct 18. doi: 10.1002/acn3.51679. Online ahead of print.
Bi-allelic variants in Iron-Sulfur Cluster Scaffold (NFU1) have previously been associated with multiple mitochondrial dysfunctions syndrome 1 (MMDS1) characterized by early-onset rapidly fatal leukoencephalopathy. We report 19 affected individuals from 10 independent families with ultra-rare bi-allelic NFU1 missense variants associated with a spectrum of early-onset pure to complex hereditary spastic paraplegia (HSP) phenotype with a longer survival (16/19) on one end and neurodevelopmental delay with severe hypotonia (3/19) on the other. Reversible or irreversible neurological decompensation after a febrile illness was common in the cohort, and there were invariable white matter abnormalities on neuroimaging. The study suggests that MMDS1 and HSP could be the two ends of the NFU1-related phenotypic continuum.
October 18, 2022
Bi-allelic loss-of-function variants in TMEM147 cause moderate to profound intellectual disability with facial dysmorphism and pseudo-Pelger-Huët anomaly
Thomas Q, Motta M, Gautier T, Zaki MS, Ciolfi A, Paccaud J, Girodon F, Boespflug-Tanguy O, Besnard T, Kerkhof J, McConkey H, Masson A, Denommé-Pichon AS, Cogné B, Trochu E, Vignard V, El It F, Rodan LH, Alkhateeb MA, Jamra RA, Duplomb L, Tisserant E, Duffourd Y, Bruel AL, Jackson A, Banka S, McEntagart M, Saggar A, Gleeson JG, Sievert D, Bae H, Lee BH, Kwon K, Seo GH, Lee H, Saeed A, Anjum N, Cheema H, Alawbathani S, Khan I, Pinto-Basto J, Teoh J, Wong J, Sahari UBM, Houlden H, Zhelcheska K, Pannetier M, Awad MA, Lesieur-Sebellin M, Barcia G, Amiel J, Delanne J, Philippe C, Faivre L, Odent S, Bertoli-Avella A, Thauvin C, Sadikovic B, Reversade B, Maroofian R, Govin J, Tartaglia M, Vitobello A.
Am J Hum Genet. 2022 Aug 23:S0002-9297(22)00360-3. doi: 10.1016/j.ajhg.2022.08.008. Online ahead of print.
The transmembrane protein TMEM147 has a dual function: first at the nuclear envelope, where it anchors lamin B receptor (LBR) to the inner membrane, and second at the endoplasmic reticulum (ER), where it facilitates the translation of nascent polypeptides within the ribosome-bound TMCO1 translocon complex. Through international data sharing, we identified 23 individuals from 15 unrelated families with bi-allelic TMEM147 loss-of-function variants, including splice-site, nonsense, frameshift, and missense variants. These affected children displayed congruent clinical features including coarse facies, developmental delay, intellectual disability, and behavioral problems. In silico structural analyses predicted disruptive consequences of the identified amino acid substitutions on translocon complex assembly and/or function, and in vitro analyses documented accelerated protein degradation via the autophagy-lysosomal-mediated pathway. Furthermore, TMEM147-deficient cells showed CKAP4 (CLIMP-63) and RTN4 (NOGO) upregulation with a concomitant reorientation of the ER, which was also witnessed in primary fibroblast cell culture. LBR mislocalization and nuclear segmentation was observed in primary fibroblast cells. Abnormal nuclear segmentation and chromatin compaction were also observed in approximately 20% of neutrophils, indicating the presence of a pseudo-Pelger-Huët anomaly. Finally, co-expression analysis revealed significant correlation with neurodevelopmental genes in the brain, further supporting a role of TMEM147 in neurodevelopment. Our findings provide clinical, genetic, and functional evidence that bi-allelic loss-of-function variants in TMEM147 cause syndromic intellectual disability due to ER-translocon and nuclear organization dysfunction.
August 23, 2022
Analysis of somatic mutations in 131 human brains reveals aging-associated hypermutability
Bae T, Fasching L, Wang Y, Shin JH, Suvakov M, Jang Y, Norton S, Dias C, Mariani J, Jourdon A, Wu F, Panda A, Pattni R, Chahine Y, Yeh R, Roberts RC, Huttner A, Kleinman JE, Hyde TM, Straub RE, Walsh CA; Brain Somatic Mosaicism Network§, Urban AE, Leckman JF, Weinberger DR, Vaccarino FM, Abyzov A, Walsh CA, Park PJ, Sestan N, Weinberger D, Moran JV, Gage FH, Vaccarino FM, Gleeson J, Mathern G, Courchesne E, Roy S, Chess AJ, Akbarian S, Bizzotto S, Coulter M, Dias C, D’Gama A, Ganz J, Hill R, Huang AY, Khoshkhoo S, Kim S, Lee A, Lodato M, Maury EA, Miller M, Borges-Monroy R, Rodin R, Zhou Z, Bohrson C, Chu C, Cortes-Ciriano I, Dou Y, Galor A, Gulhan D, Kwon M, Luquette J, Sherman M, Viswanadham V, Jones A, Rosenbluh C, Cho S, Langmead B, Thorpe J, Erwin J, Jaffe A, McConnell M, Narurkar R, Paquola A, Shin J, Straub R, Abyzov A, Bae T, Jang Y, Wang Y, Molitor C, Peters M, Linker S, Reed P, Wang M, Urban A, Zhou B, Zhu X, Pattni R, Serres Amero A, Juan D, Lobon I, Marques-Bonet T, Solis Moruno M, Garcia Perez R, Povolotskaya I, Soriano E, Antaki D, Averbuj D, Ball L, Breuss M, Yang X, Chung C, Emery SB, Flasch DA, Kidd JM, Kopera HC, Kwan KY, Mills RE, Moldovan JB, Sun C, Zhao X, Zhou W, Frisbie TJ, Cherskov A, Fasching L, Jourdon A, Pochareddy S, Scuderi S.
Science. 2022 Jul 29;377(6605):511-517. doi: 10.1126/science.abm6222. Epub 2022 Jul 28.
We analyzed 131 human brains (44 neurotypical, 19 with Tourette syndrome, 9 with schizophrenia, and 59 with autism) for somatic mutations after whole genome sequencing to a depth of more than 200×. Typically, brains had 20 to 60 detectable single-nucleotide mutations, but ~6% of brains harbored hundreds of somatic mutations. Hypermutability was associated with age and damaging mutations in genes implicated in cancers and, in some brains, reflected in vivo clonal expansions. Somatic duplications, likely arising during development, were found in ~5% of normal and diseased brains, reflecting background mutagenesis. Brains with autism were associated with mutations creating putative transcription factor binding motifs in enhancer-like regions in the developing brain. The top-ranked affected motifs corresponded to MEIS (myeloid ectopic viral integration site) transcription factors, suggesting a potential link between their involvement in gene regulation and autism.
July 29, 2022