Caenorhabditis elegans provides an efficient drug screening platform for GNAO1-related disorders and highlights the potential role of caffeine in controlling dyskinesia
Di Rocco M, Galosi S, Lanza E, Tosato F, Caprini D, Folli V, Friedman J, Bocchinfuso G, Martire A, Di Schiavi E, Leuzzi V, Martinelli S.
Hum Mol Genet. 2021 Oct 8:ddab296. doi: 10.1093/hmg/ddab296. Online ahead of print.
Dominant GNAO1 mutations cause an emerging group of childhood-onset neurological disorders characterized by developmental delay, intellectual disability, movement disorders, drug-resistant seizures, and neurological deterioration. GNAO1 encodes the α-subunit of an inhibitory GTP/GDP-binding protein regulating ion channel activity and neurotransmitter release. The pathogenic mechanisms underlying GNAO1-related disorders remain largely elusive and there are no effective therapies. Here, we assessed the functional impact of two disease-causing variants associated with distinct clinical features, c.139A > G (p.S47G) and c.662C > A (p.A221D), using Caenorhabditis elegans as a model organism. The c.139A > G change was introduced into the orthologous position of the C. elegans gene via CRISPR/Cas9, whereas a knock-in strain carrying the p.A221D variant was already available. Like null mutants, homozygous knock-in animals showed increased egg laying and were hypersensitive to aldicarb, an inhibitor of acetylcholinesterase, suggesting excessive neurotransmitter release by different classes of motor neurons. Automated analysis of C. elegans locomotion indicated that goa-1 mutants move faster than control animals, with more frequent body bends and a higher reversal rate, and display uncoordinated locomotion. Phenotypic profiling of heterozygous animals revealed a strong hypomorphic effect of both variants, with a partial dominant-negative activity for the p.A221D allele. Finally, caffeine was shown to rescue aberrant motor function in C. elegans harboring the goa-1 variants; this effect is mainly exerted through adenosine receptor antagonism. Overall, our findings establish a suitable platform for drug discovery, which may assist in accelerating the development of new therapies for this devastating condition, and highlight the potential role of caffeine in controlling GNAO1-related dyskinesia.
October 8, 2021
Dual orexin receptor antagonists for insomnia in youth with neurodevelopmental disorders: a case series and review
Besterman AD, Jeste SS
Eur Child Adolesc Psychiatry. 2021 Oct 5. doi: 10.1007/s00787-021-01883-7. Online ahead of print.
Insomnia is a common, impairing, and difficult-to-treat comorbidity in children with neurodevelopmental disorders (NDDs). Behavioral interventions can be challenging because of developmental and behavioral features that interfere with treatment. Medication management also can be difficult due to a high burden of side effects, a high rate of paradoxical responses, and frequent treatment resistance. Therefore, new treatment options for insomnia in children with NDDs are needed. Dual orexin receptor antagonists (DORAs) are a relatively new class of pharmacotherapeutics that induce sleep by inhibiting the orexin signaling pathway. To date, there is little safety or efficacy data on the use of DORAs in children with NDDs. We present four patients with NDDs and insomnia that we treated with the DORA, suvorexant. We found that patients had a wide range of responses, with one patient displaying a robust improvement in sleep onset and maintenance, while another had significant improvement in insomnia symptoms on combination therapy with trazodone. Our final two patients had mild or no benefit from suvorexant therapy. Further research is necessary to establish the safety and efficacy of DORAs in this population and to identify predictive factors, such as specific neurogenetic diagnoses or clinical features, of a positive treatment response.
October 6, 2021
Biallelic variants in SLC38A3 encoding a glutamine transporter cause epileptic encephalopathy
Marafi D, Fatih JM, Kaiyrzhanov R, Ferla MP, Gijavanekar C, Al-Maraghi A, Liu N, Sites E, Alsaif HS, Al-Owain M, Zakkariah M, El-Anany E, Guliyeva U, Guliyeva S, Gaba C, Haseeb A, Alhashem AM, Danish E, Karageorgou V, Beetz C, Subhi AA, Mullegama SV, Torti E, Sebastin M, Breilyn MS, Duberstein S, Abdel-Hamid MS, Mitani T, Du H, Rosenfeld JA, Jhangiani SN, Coban Akdemir Z, Gibbs RA, Taylor JC, Fakhro KA, Hunter JV, Pehlivan D, Zaki MS, Gleeson JG, Maroofian R, Houlden H, Posey JE, Sutton VR, Alkuraya FS, Elsea SH, Lupski JR
Brain. 2021 Oct 4:awab369. doi: 10.1093/brain/awab369. Online ahead of print.
The solute carrier (SLC) superfamily encompasses >400 transmembrane transporters involved in the exchange of amino acids, nutrients, ions, metals, neurotransmitters and metabolites across biological membranes. SLCs are highly expressed in the mammalian brain; defects in nearly 100 unique SLC-encoding genes (OMIM: https://www.omim.org) are associated with rare Mendelian disorders including developmental and epileptic encephalopathy (DEE) and severe neurodevelopmental disorders (NDDs). Exome sequencing and family-based rare variant analyses on a cohort with NDD identified two siblings with DEE and a shared deleterious homozygous splicing variant in SLC38A3. The gene encodes SNAT3, a sodium-coupled neutral amino acid transporter and a principal transporter of the amino acids asparagine, histidine, and glutamine, the latter being the precursor for the neurotransmitters GABA and glutamate. Additional subjects with a similar DEE phenotype and biallelic predicted-damaging SLC38A3 variants were ascertained through GeneMatcher and collaborations with research and clinical molecular diagnostic laboratories. Untargeted metabolomic analysis was performed to identify novel metabolic biomarkers. Ten individuals from seven unrelated families from six different countries with deleterious biallelic variants in SLC38A3 were identified. Global developmental delay, intellectual disability, hypotonia, and absent speech were common features while microcephaly, epilepsy, and visual impairment were present in the majority. Epilepsy was drug-resistant in half. Metabolomic analysis revealed perturbations of glutamate, histidine, and nitrogen metabolism in plasma, urine, and cerebrospinal fluid of selected subjects, potentially representing biomarkers of disease. Our data support the contention that SLC38A3 is a novel disease gene for DEE and illuminate the likely pathophysiology of the disease as perturbations in glutamine homeostasis.
October 5, 2021
ABHD16A deficiency causes a complicated form of hereditary spastic paraplegia associated with intellectual disability and cerebral anomalies
Lemire G, Ito YA, Marshall AE, Chrestian N, Stanley V, Brady L, Tarnopolsky M, Curry CJ, Hartley T, Mears W, Derksen A, Rioux N, Laflamme N, Hutchison HT, Pais LS, Zaki MS, Sultan T, Dane AD; Care4Rare Canada Consortium, Gleeson JG, Vaz FM, Kernohan KD, Bernard G, Boycott KM
Am J Hum Genet. 2021 Sep 21:S0002-9297(21)00341-4. doi: 10.1016/j.ajhg.2021.09.005. Online ahead of print.
ABHD16A (abhydrolase domain-containing protein 16A, phospholipase) encodes the major phosphatidylserine (PS) lipase in the brain. PS lipase synthesizes lysophosphatidylserine, an important signaling lipid that functions in the mammalian central nervous system. ABHD16A has not yet been associated with a human disease. In this report, we present a cohort of 11 affected individuals from six unrelated families with a complicated form of hereditary spastic paraplegia (HSP) who carry bi-allelic deleterious variants in ABHD16A. Affected individuals present with a similar phenotype consisting of global developmental delay/intellectual disability, progressive spasticity affecting the upper and lower limbs, and corpus callosum and white matter anomalies. Immunoblot analysis on extracts from fibroblasts from four affected individuals demonstrated little to no ABHD16A protein levels compared to controls. Our findings add ABHD16A to the growing list of lipid genes in which dysregulation can cause complicated forms of HSP and begin to describe the molecular etiology of this condition.
September 30, 2021
A Human Pleiotropic Multiorgan Condition Caused by Deficient Wnt Secretion
Chai G, Szenker-Ravi E, Chung C, Li Z, Wang L, Khatoo M, Marshall T, Jiang N, Yang X, McEvoy-Venneri J, Stanley V, Anzenberg P, Lang N, Wazny V, Yu J, Virshup DM, Nygaard R, Mancia F, Merdzanic R, Toralles MBP, Pitanga PML, Puri RD, Hernan R, Chung WK, Bertoli-Avella AM, Al-Sannaa N, Zaki MS, Willert K, Reversade B, Gleeson JG
N Engl J Med. 2021 Sep 30;385(14):1292-1301. doi: 10.1056/NEJMoa2033911.
BACKGROUND: Structural birth defects occur in approximately 3% of live births; most such defects lack defined genetic or environmental causes. Despite advances in surgical approaches, pharmacologic prevention remains largely out of reach.
METHODS: We queried worldwide databases of 20,248 families that included children with neurodevelopmental disorders and that were enriched for parental consanguinity. Approximately one third of affected children in these families presented with structural birth defects or microcephaly. We performed exome or genome sequencing of samples obtained from the children, their parents, or both to identify genes with biallelic pathogenic or likely pathogenic mutations present in more than one family. After identifying disease-causing variants, we generated two mouse models, each with a pathogenic variant “knocked in,” to study mechanisms and test candidate treatments. We administered a small-molecule Wnt agonist to pregnant animals and assessed their offspring.
RESULTS: We identified homozygous mutations in WLS, which encodes the Wnt ligand secretion mediator (also known as Wntless or WLS) in 10 affected persons from 5 unrelated families. (The Wnt ligand secretion mediator is essential for the secretion of all Wnt proteins.) Patients had multiorgan defects, including microcephaly and facial dysmorphism as well as foot syndactyly, renal agenesis, alopecia, iris coloboma, and heart defects. The mutations affected WLS protein stability and Wnt signaling. Knock-in mice showed tissue and cell vulnerability consistent with Wnt-signaling intensity and individual and collective functions of Wnts in embryogenesis. Administration of a pharmacologic Wnt agonist partially restored embryonic development.
CONCLUSIONS: Genetic variations affecting a central Wnt regulator caused syndromic structural birth defects. Results from mouse models suggest that what we have named Zaki syndrome is a potentially preventable disorder. (Funded by the National Institutes of Health and others.).
September 30, 2021
Insights into the expanding phenotypic spectrum of inherited disorders of biogenic amines
Kuseyri Hübschmann O, Horvath G, Cortès-Saladelafont E, Yıldız Y, Mastrangelo M, Pons R, Friedman J, Mercimek-Andrews S, Wong SN, Pearson TS, Zafeiriou DI, Kulhánek J, Kurian MA, López-Laso E, Oppebøen M, Kılavuz S, Wassenberg T, Goez H, Scholl-Bürgi S, Porta F, Honzík T, Santer R, Burlina A, Sivri HS, Leuzzi V, Hoffmann GF, Jeltsch K, Hübschmann D, Garbade SF; iNTD Registry Study Group, García-Cazorla A, Opladen T.
Nat Commun. 2021 Sep 20;12(1):5529. doi: 10.1038/s41467-021-25515-5.
Inherited disorders of neurotransmitter metabolism are rare neurodevelopmental diseases presenting with movement disorders and global developmental delay. This study presents the results of the first standardized deep phenotyping approach and describes the clinical and biochemical presentation at disease onset as well as diagnostic approaches of 275 patients from the registry of the International Working Group on Neurotransmitter related Disorders. The results reveal an increased rate of prematurity, a high risk for being small for gestational age and for congenital microcephaly in some disorders. Age at diagnosis and the diagnostic delay are influenced by the diagnostic methods applied and by disease-specific symptoms. The timepoint of investigation was also a significant factor: delay to diagnosis has decreased in recent years, possibly due to novel diagnostic approaches or raised awareness. Although each disorder has a specific biochemical pattern, we observed confounding exceptions to the rule. The data provide comprehensive insights into the phenotypic spectrum of neurotransmitter disorders.
September 23, 2021
A human three-dimensional neural-perivascular ‘assembloid’ promotes astrocytic development and enables modeling of SARS-CoV-2 neuropathology
Lu Wang, David Sievert, Alex E. Clark, Sangmoon Lee, Hannah Federman, Benjamin D. Gastfriend, Eric V. Shusta, Sean P. Palecek, Aaron F. Carlin & Joseph G. Gleeson
Nat Med. 2021 Jul 9. doi: 10.1038/s41591-021-01443-1. Online ahead of print.
Clinical evidence suggests the central nervous system is frequently impacted by SARS-CoV-2 infection, either directly or indirectly, although the mechanisms are unclear. Pericytes are perivascular cells within the brain that are proposed as SARS-CoV-2 infection points. Here we show that pericyte-like cells (PLCs), when integrated into a cortical organoid, are capable of infection with authentic SARS-CoV-2. Before infection, PLCs elicited astrocytic maturation and production of basement membrane components, features attributed to pericyte functions in vivo. While traditional cortical organoids showed little evidence of infection, PLCs within cortical organoids served as viral ‘replication hubs’, with virus spreading to astrocytes and mediating inflammatory type I interferon transcriptional responses. Therefore, PLC-containing cortical organoids (PCCOs) represent a new ‘assembloid’ model that supports astrocytic maturation as well as SARS-CoV-2 entry and replication in neural tissue; thus, PCCOs serve as an experimental model for neural infection.
July 12, 2021
Biallelic variants in KARS1 are associated with neurodevelopmental disorders and hearing loss recapitulated by the knockout zebrafish
Lin SJ, Vona B, Barbalho PG, Kaiyrzhanov R, Maroofian R, Petree C, Severino M, Stanley V, Varshney P, Bahena P, Alzahrani F, Alhashem A, Pagnamenta AT, Aubertin G, Estrada-Veras JI, Hernández HAD, Mazaheri N, Oza A, Thies J, Renaud DL, Dugad S, McEvoy J, Sultan T, Pais LS, Tabarki B, Villalobos-Ramirez D, Rad A; Genomics England Research Consortium, Galehdari H, Ashrafzadeh F, Sahebzamani A, Saeidi K, Torti E, Elloumi HZ, Mora S, Palculict TB, Yang H, Wren JD, Ben Fowler, Joshi M, Behra M, Burgess SM, Nath SK, Hanna MG, Kenna M, Merritt JL 2nd, Houlden H, Karimiani EG, Zaki MS, Haaf T, Alkuraya FS, Gleeson JG, Varshney GK.
Genet Med. 2021 Jun 25. doi: 10.1038/s41436-021-01239-1. Online ahead of print.
PURPOSE: Pathogenic variants in Lysyl-tRNA synthetase 1 (KARS1) have increasingly been recognized as a cause of early-onset complex neurological phenotypes. To advance the timely diagnosis of KARS1-related disorders, we sought to delineate its phenotype and generate a disease model to understand its function in vivo.
METHODS: Through international collaboration, we identified 22 affected individuals from 16 unrelated families harboring biallelic likely pathogenic or pathogenic in KARS1 variants. Sequencing approaches ranged from disease-specific panels to genome sequencing. We generated loss-of-function alleles in zebrafish.
RESULTS: We identify ten new and four known biallelic missense variants in KARS1 presenting with a moderate-to-severe developmental delay, progressive neurological and neurosensory abnormalities, and variable white matter involvement. We describe novel KARS1-associated signs such as autism, hyperactive behavior, pontine hypoplasia, and cerebellar atrophy with prevalent vermian involvement. Loss of kars1 leads to upregulation of p53, tissue-specific apoptosis, and downregulation of neurodevelopmental related genes, recapitulating key tissue-specific disease phenotypes of patients. Inhibition of p53 rescued several defects of kars1-/- knockouts.
CONCLUSION: Our work delineates the clinical spectrum associated with KARS1 defects and provides a novel animal model for KARS1-related human diseases revealing p53 signaling components as potential therapeutic targets.
June 25, 2021
Loss of function mutations in GEMIN5 cause a neurodevelopmental disorder
Kour S, Rajan DS, Fortuna TR, Anderson EN, Ward C, Lee Y, Lee S, Shin YB, Chae JH, Choi M, Siquier K, Cantagrel V, Amiel J, Stolerman ES, Barnett SS, Cousin MA, Castro D, McDonald K, Kirmse B, Nemeth AH, Rajasundaram D, Innes AM, Lynch D, Frosk P, Collins A, Gibbons M, Yang M, Desguerre I, Boddaert N, Gitiaux C, Rydning SL, Selmer KK, Urreizti R, Garcia-Oguiza A, Osorio AN, Verdura E, Pujol A, McCurry HR, Landers JE, Agnihotri S, Andriescu EC, Moody SB, Phornphutkul C, Sacoto MJG, Begtrup A, Houlden H, Kirschner J, Schorling D, Rudnik-Schöneborn S, Strom TM, Leiz S, Juliette K, Richardson R, Yang Y, Zhang Y, Wang M, Wang J, Wang X, Platzer K, Donkervoort S, Bönnemann CG, Wagner M, Issa MY, Elbendary HM, Stanley V, Maroofian R, Gleeson JG, Zaki MS, Senderek J, Pandey UB.
Nat Commun. 2021 May 7;12(1):2558. doi: 10.1038/s41467-021-22627-w.
GEMIN5, an RNA-binding protein is essential for assembly of the survival motor neuron (SMN) protein complex and facilitates the formation of small nuclear ribonucleoproteins (snRNPs), the building blocks of spliceosomes. Here, we have identified 30 affected individuals from 22 unrelated families presenting with developmental delay, hypotonia, and cerebellar ataxia harboring biallelic variants in the GEMIN5 gene. Mutations in GEMIN5 perturb the subcellular distribution, stability, and expression of GEMIN5 protein and its interacting partners in patient iPSC-derived neurons, suggesting a potential loss-of-function mechanism. GEMIN5 mutations result in disruption of snRNP complex assembly formation in patient iPSC neurons. Furthermore, knock down of rigor mortis, the fly homolog of human GEMIN5, leads to developmental defects, motor dysfunction, and a reduced lifespan. Interestingly, we observed that GEMIN5 variants disrupt a distinct set of transcripts and pathways as compared to SMA patient neurons, suggesting different molecular pathomechanisms. These findings collectively provide evidence that pathogenic variants in GEMIN5 perturb physiological functions and result in a neurodevelopmental delay and ataxia syndrome.
May 11, 2021