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
Functional and structural analyses of novel Smith-Kingsmore Syndrome-Associated MTOR variants reveal potential new mechanisms and predictors of pathogenicity
Besterman AD, Althoff T, Elfferich P, Gutierrez-Mejia I, Sadik J, Bernstein JA, van Ierland Y, Kattentidt-Mouravieva AA, Nellist M, Abramson J, Martinez-Agosto JA.
PLoS Genet. 2021 Jul 1;17(7):e1009651. doi: 10.1371/journal.pgen.1009651. Online ahead of print.
Smith-Kingsmore syndrome (SKS) is a rare neurodevelopmental disorder characterized by macrocephaly/megalencephaly, developmental delay, intellectual disability, hypotonia, and seizures. It is caused by dominant missense mutations in MTOR. The pathogenicity of novel variants in MTOR in patients with neurodevelopmental disorders can be difficult to determine and the mechanism by which variants cause disease remains poorly understood. We report 7 patients with SKS with 4 novel MTOR variants and describe their phenotypes. We perform in vitro functional analyses to confirm MTOR activation and interrogate disease mechanisms. We complete structural analyses to understand the 3D properties of pathogenic variants. We examine the accuracy of relative accessible surface area, a quantitative measure of amino acid side-chain accessibility, as a predictor of MTOR variant pathogenicity. We describe novel clinical features of patients with SKS. We confirm MTOR Complex 1 activation and identify MTOR Complex 2 activation as a new potential mechanism of disease in SKS. We find that pathogenic MTOR variants disproportionately cluster in hotspots in the core of the protein, where they disrupt alpha helix packing due to the insertion of bulky amino acid side chains. We find that relative accessible surface area is significantly lower for SKS-associated variants compared to benign variants. We expand the phenotype of SKS and demonstrate that additional pathways of activation may contribute to disease. Incorporating 3D properties of MTOR variants may help in pathogenicity classification. We hope these findings may contribute to improving the precision of care and therapeutic development for individuals with SKS.
July 9, 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
Postmortem whole-genome sequencing on a dried blood spot identifies a novel homozygous SUOX variant causing isolated sulfite oxidase deficiency
Owen MJ, Lenberg J, Feigenbaum A, Gold J, Chau K, Bezares-Orin Z, Ding Y, Chowdhury S, Kingsmore SF.
Cold Spring Harb Mol Case Stud. 2021 Jun 11;7(3):a006091. doi: 10.1101/mcs.a006091. Print 2021 Jun.
Rapid whole-genome sequencing (rWGS) has shown that genetic diseases are a common cause of infant mortality in neonatal intensive care units. Dried blood spots collected for newborn screening allow investigation of causes of infant mortality that were not diagnosed during life. Here, we present a neonate who developed seizures and encephalopathy on the third day of life that was refractory to antiepileptic medications. The patient died on day of life 16 after progressive respiratory failure and sepsis. The parents had lost two prior children after similar presentations, neither of whom had a definitive diagnosis. Postmortem rWGS of a dried blood spot identified a pathogenic homozygous frameshift variant in the SUOX gene associated with isolated sulfite oxidase deficiency (c.1390_1391del, p.Leu464GlyfsTer10). This case highlights that early, accurate molecular diagnosis has the potential to influence prenatal counseling and guide management in rare, genetic disorders and has added importance in cases of a strong family history and risk factors such as consanguinity.
June 14, 2021
Project Baby Bear: Rapid precision care incorporating rWGS in 5 California children’s hospitals demonstrates improved clinical outcomes and reduced costs of care
Dimmock D, Caylor S, Waldman B, Benson W, Ashburner C, Carmichael JL, Carroll J, Cham E, Chowdhury S, Cleary J, D’Harlingue A, Doshi A, Ellsworth K, Galarreta CI, Hobbs C, Houtchens K, Hunt J, Joe P, Joseph M, Kaplan RH, Kingsmore SF, Knight J, Kochhar A, Kronick RG, Limon J, Martin M, Rauen KA, Schwarz A, Shankar SP, Spicer R, Rojas MA, Vargas-Shiraishi O, Wigby K, Zadeh N, Farnaes L.
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Am J Hum Genet. 2021 May 29:S0002-9297(21)00192-0. doi: 10.1016/j.ajhg.2021.05.008. Online ahead of print.
Genetic disorders are a leading contributor to mortality in neonatal and pediatric intensive care units (ICUs). Rapid whole-genome sequencing (rWGS)-based rapid precision medicine (RPM) is an intervention that has demonstrated improved clinical outcomes and reduced costs of care. However, the feasibility of broad clinical deployment has not been established. The objective of this study was to implement RPM based on rWGS and evaluate the clinical and economic impact of this implementation as a first line diagnostic test in the California Medicaid (Medi-Cal) program. Project Baby Bear was a payor funded, prospective, real-world quality improvement project in the regional ICUs of five tertiary care children’s hospitals. Participation was limited to acutely ill Medi-Cal beneficiaries who were admitted November 2018 to May 2020, were <1 year old and within one week of hospitalization, or had just developed an abnormal response to therapy. The whole cohort received RPM. There were two prespecified primary outcomes-changes in medical care reported by physicians and changes in the cost of care. The majority of infants were from underserved populations. Of 184 infants enrolled, 74 (40%) received a diagnosis by rWGS that explained their admission in a median time of 3 days. In 58 (32%) affected individuals, rWGS led to changes in medical care. Testing and precision medicine cost $1.7 million and led to $2.2-2.9 million cost savings. rWGS-based RPM had clinical utility and reduced net health care expenditures for infants in regional ICUs. rWGS should be considered early in ICU admission when the underlying etiology is unclear.
PMID:34089648 | DOI:10.1016/j.ajhg.2021.05.008
June 7, 2021
RPM for NICU and PICUrWGS
Rapid Sequencing-Based Diagnosis of Thiamine Metabolism Dysfunction Syndrome
Owen MJ, Niemi AK, Dimmock DP, Speziale M, Nespeca M, Chau KK, Van Der Kraan L, Wright MS, Hansen C, Veeraraghavan N, Ding Y, Lenberg J, Chowdhury S, Hobbs CA, Batalov S, Zhu Z, Nahas SA, Gilmer S, Knight G, Lefebvre S, Reynders J, Defay T, Weir J, Thomson VS, Fraser L, Lajoie BR, McPhail TK, Mehtalia SS, Kunard CM, Hall KP, Kingsmore SF.
June 3, 2021
Ending a diagnostic odyssey: Moving from exome to genome to identify cockayne syndrome
Friedman J, Bird LM, Haas R, Robbins SL, Nahas SA, Dimmock DP, Yousefzadeh MJ, Witt MA, Niedernhofer LJ, Chowdhury S.
Mol Genet Genomic Med. 2021 Jun 2:e1623. doi: 10.1002/mgg3.1623. Online ahead of print.
BACKGROUND: Cockayne syndrome (CS) is a rare autosomal recessive disorder characterized by growth failure and multisystemic degeneration. Excision repair cross-complementation group 6 (ERCC6 OMIM: *609413) is the gene most frequently mutated in CS.
METHODS: A child with pre and postnatal growth failure and progressive neurologic deterioration with multisystem involvement, and with nondiagnostic whole-exome sequencing, was screened for causal variants with whole-genome sequencing (WGS).
RESULTS: WGS identified biallelic ERCC6 variants, including a previously unreported intronic variant. Pathogenicity of these variants was established by demonstrating reduced levels of ERCC6 mRNA and protein expression, normal unscheduled DNA synthesis, and impaired recovery of RNA synthesis in patient fibroblasts following UV-irradiation.
CONCLUSION: The study confirms the pathogenicity of a previously undescribed upstream intronic variant, highlighting the power of genome sequencing to identify noncoding variants. In addition, this report provides evidence for the utility of a combination approach of genome sequencing plus functional studies to provide diagnosis in a child for whom a lengthy diagnostic odyssey, including exome sequencing, was previously unrevealing.
June 2, 2021
Genetic Neurologic DiseaseRare Disease
Quantitative analysis of the natural history of prolidase deficiency: description of 17 families and systematic review of published cases
Rossignol F, Duarte Moreno MS, Benoist JF, Boehm M, Bourrat E, Cano A, Chabrol B, Cosson C, Díaz JLD, D’Harlingue A, Dimmock D, Freeman AF, García MT, Garganta C, Goerge T, Halbach SS, de Laffolie J, Lam CT, Martin L, Martins E, Meinhardt A, Melki I, Ombrello AK, Pérez N, Quelhas D, Scott A, Slavotinek AM, Soares AR, Stein SL, Süßmuth K, Thies J, Ferreira CR, Schiff M.
Genet Med. 2021 May 26. doi: 10.1038/s41436-021-01200-2. Online ahead of print.
PURPOSE: Prolidase deficiency is a rare inborn error of metabolism causing ulcers and other skin disorders, splenomegaly, developmental delay, and recurrent infections. Most of the literature is constituted of isolated case reports. We aim to provide a quantitative description of the natural history of the condition by describing 19 affected individuals and reviewing the literature.
METHODS: Nineteen patients were phenotyped per local institutional procedures. A systematic review following PRISMA criteria identified 132 articles describing 161 patients. Main outcome analyses were performed for manifestation frequency, diagnostic delay, overall survival, symptom-free survival, and ulcer-free survival.
RESULTS: Our cohort presented a wide variability of severity. Autoimmune disorders were found in 6/19, including Crohn disease, systemic lupus erythematosus, and arthritis. Another immune finding was hemophagocytic lymphohistiocytosis (HLH). Half of published patients were symptomatic by age 4 and had a delayed diagnosis (mean delay 11.6 years). Ulcers were present initially in only 30% of cases, with a median age of onset at 12 years old.
CONCLUSION: Prolidase deficiency has a broad range of manifestations. Symptoms at onset may be nonspecific, likely contributing to the diagnostic delay. Testing for this disorder should be considered in any child with unexplained autoimmunity, lower extremity ulcers, splenomegaly, or HLH.
June 2, 2021
Loss of C2orf69 defines a fatal autoinflammatory syndrome in humans and zebrafish that evokes a glycogen storage-associated mitochondriopathy
Am J Hum Genet. 2021 May 21:S0002-9297(21)00187-7. doi: 10.1016/j.ajhg.2021.05.003. Online ahead of print.
Human C2orf69 is an evolutionarily conserved gene whose function is unknown. Here, we report eight unrelated families from which 20 children presented with a fatal syndrome consisting of severe autoinflammation and progredient leukoencephalopathy with recurrent seizures; 12 of these subjects, whose DNA was available, segregated homozygous loss-of-function C2orf69 variants. C2ORF69 bears homology to esterase enzymes, and orthologs can be found in most eukaryotic genomes, including that of unicellular phytoplankton. We found that endogenous C2ORF69 (1) is loosely bound to mitochondria, (2) affects mitochondrial membrane potential and oxidative respiration in cultured neurons, and (3) controls the levels of the glycogen branching enzyme 1 (GBE1) consistent with a glycogen storage-associated mitochondriopathy. We show that CRISPR-Cas9-mediated inactivation of zebrafish C2orf69 results in lethality by 8 months of age due to spontaneous epileptic seizures, which is preceded by persistent brain inflammation. Collectively, our results delineate an autoinflammatory Mendelian disorder of C2orf69 deficiency that disrupts the development/homeostasis of the immune and central nervous systems.
May 27, 2021
Implementing Rapid Whole Genome Sequencing in Critical Care: A Qualitative Study of Facilitators and Barriers to New Technology Adoption
Franck LS, Kriz RM, Rego S, Garman K, Hobbs C, Dimmock D.
J Pediatr. 2021 May 20:S0022-3476(21)00496-0. doi: 10.1016/j.jpeds.2021.05.045. Online ahead of print.
OBJECTIVE: To characterize the views of members of the multi-disciplinary team regarding the implementation of Rapid Whole Genome Sequencing (rWGS) as a first-tier test for critically ill children in diverse children’s hospital settings.
STUDY DESIGN: Qualitative interviews informed by implementation science theory were conducted with the multi-disciplinary patient care teams and hospital leaders at each of the five tertiary care children’s hospitals involved in a statewide rWGS implementation project.
RESULTS: Our analysis revealed 5 key themes regarding the implementation process across the sites: the need for rWGS champions, educational needs and strategies, negotiating decision-making roles and processes, workflows and workarounds, and perceptions about rWGS. From the findings a composite clinical workflow diagram was developed to summarize all of the processes involved in the implementation of the test, and the key areas where implementation practices differed.
CONCLUSIONS: These findings provide insights for design of interventions to support adoption, scale-up and sustainability of rWGS and other novel technologies in neonatal and pediatric critical care settings.
May 24, 2021