Scientific Publications

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183 Results

2021

Biallelic FRA10AC1 variants cause a neurodevelopmental disorder with growth retardation

von Elsner L, Chai G, Schneeberger PE, Harms FL, Casar C, Qi M, Alawi M, Abdel-Salam GMH, Zaki MS, Arndt F, Yang X, Stanley V, Hempel M, Gleeson JG, Kutsche K

Brain. 2021 Oct 25:awab403. doi: 10.1093/brain/awab403. Online ahead of print. ABSTRACT The major spliceosome mediates pre-mRNA splicing by recognizing the highly conserved sequences at the 5′ and 3′ splice sites and the branch point. More than 150 proteins participate in the splicing process and are organized in the spliceosomal A, B, and C complexes. FRA10AC1 is a peripheral protein of the spliceosomal C complex and its ortholog in the green alga facilitates recognition or interaction with splice sites. We identified biallelic pathogenic variants in FRA10AC1 in five individuals from three consanguineous families. The two unrelated patients 1 and 2 with loss-of-function variants showed developmental delay, intellectual disability, and no speech, while three siblings with the c.494_496delAAG (p.Glu165del) variant had borderline to mild intellectual disability. All patients had microcephaly, hypoplasia or agenesis of the corpus callosum, growth retardation, and craniofacial dysmorphism. FRA10AC1 transcripts and proteins were drastically reduced or absent in fibroblasts of patients 1 and 2. In a heterologous expression system, the p. Glu165del variant impacts intrinsic stability of FRA10AC1 but does not affect its nuclear localization. By co-immunoprecipitation, we found ectopically expressed HA-FRA10AC1 in complex with endogenous DGCR14, another component of the spliceosomal C complex, while the splice factors CHERP, NKAP, RED, and SF3B2 could not be co-immunoprecipitated. Using an in vitro splicing reporter assay, we did not obtain evidence for FRA10AC1 deficiency to suppress missplicing events caused by mutations in the highly conserved dinucleotides of 5′ and 3′ splice sites in an in vitro splicing assay in patient-derived fibroblasts. Our data highlight the importance of specific peripheral spliceosomal C complex proteins for neurodevelopment. It remains possible that FRA10AC1 may have other and/or additional cellular functions, such as coupling of transcription and splicing reactions. PMID:34694367 | DOI:10.1093/brain/awab403

October 26, 2021
Neurogenomics

Development of therapies for rare genetic disorders of GPX4: roadmap and opportunities

Cheff DM, Muotri AR, Stockwell BR, Schmidt EE, Ran Q, Kartha RV, Johnson SC, Mittal P, Arnér ESJ, Wigby KM, Hall MD, Ramesh SK

Orphanet J Rare Dis. 2021 Oct 23;16(1):446. doi: 10.1186/s13023-021-02048-0. ABSTRACT BACKGROUND: Extremely rare progressive diseases like Sedaghatian-type Spondylometaphyseal Dysplasia (SSMD) can be neonatally lethal and therefore go undiagnosed or are difficult to treat. Recent sequencing efforts have linked this disease to mutations in GPX4, with consequences in the resulting enzyme, glutathione peroxidase 4. This offers potential diagnostic and therapeutic avenues for those suffering from this disease, though the steps toward these treatments is often convoluted, expensive, and time-consuming. MAIN BODY: The CureGPX4 organization was developed to promote awareness of GPX4-related diseases like SSMD, as well as support research that could lead to essential therapeutics for patients. We provide an overview of the 21 published SSMD cases and have compiled additional sequencing data for four previously unpublished individuals to illustrate the genetic component of SSMD, and the role of sequencing data in diagnosis. We outline in detail the steps CureGPX4 has taken to reach milestones of team creation, disease understanding, drug repurposing, and design of future studies. CONCLUSION: The primary aim of this review is to provide a roadmap for therapy development for rare, ultra-rare, and difficult to diagnose diseases, as well as increase awareness of the genetic component of SSMD. This work will offer a better understanding of GPx4-related diseases, and help guide researchers, clinicians, and patients interested in other rare diseases find a path towards treatments. PMID:34688299 | DOI:10.1186/s13023-021-02048-0

October 26, 2021
Rare Disease

Expanding the phenotypic spectrum of BCS1L-related mitochondrial disease

Hikmat O, Isohanni P, Keshavan N, Ferla MP, Fassone E, Abbott MA, Bellusci M, Darin N, Dimmock D, Ghezzi D, Houlden H, Invernizzi F, Kamarus Jaman NB, Kurian MA, Morava E, Naess K, Ortigoza-Escobar JD, Parikh S, Pennisi A, Barcia G, Tylleskär KB, Brackman D, Wortmann SB, Taylor JC, Bindoff LA, Fellman V, Rahman S.

Ann Clin Transl Neurol. 2021 Oct 18. doi: 10.1002/acn3.51470. Online ahead of print. ABSTRACT OBJECTIVE: To delineate the full phenotypic spectrum of BCS1L-related disease, provide better understanding of the genotype-phenotype correlations and identify reliable prognostic disease markers. METHODS: We performed a retrospective multinational cohort study of previously unpublished patients followed in 15 centres from 10 countries. Patients with confirmed biallelic pathogenic BCS1L variants were considered eligible. Clinical, laboratory, neuroimaging and genetic data were analysed. Patients were stratified into different groups based on the age of disease onset, whether homozygous or compound heterozygous for the c.232A>G (p.Ser78Gly) variant, and those with other pathogenic BCS1L variants. RESULTS: Thirty-three patients were included. We found that growth failure, lactic acidosis, tubulopathy, hepatopathy and early death were more frequent in those with disease onset within the first month of life. In those with onset after 1 month, neurological features including movement disorders and seizures were more frequent. Novel phenotypes, particularly involving movement disorder, were identified in this group. The presence of the c.232A>G (p.Ser78Gly) variant was associated with significantly worse survival and exclusively found in those with disease onset within the first month of life, whilst other pathogenic BCS1L variants were more frequent in those with later symptom onset. INTERPRETATION: The phenotypic spectrum of BCS1L-related disease comprises a continuum of clinical features rather than a set of separate syndromic clinical identities. Age of onset defines BCS1L-related disease clinically and early presentation is associated with poor prognosis. Genotype correlates with phenotype in the presence of the c.232A>G (p.Ser78Gly) variant. PMID:34662929 | DOI:10.1002/acn3.51470

October 19, 2021
Gene Discovery

Artificial intelligence enables comprehensive genome interpretation and nomination of candidate diagnoses for rare genetic diseases

De La Vega FM, Chowdhury S, Moore B, Frise E, McCarthy J, Hernandez EJ, Wong T, James K, Guidugli L, Agrawal PB, Genetti CA, Brownstein CA, Beggs AH, Löscher BS, Franke A, Boone B, Levy SE, Õunap K, Pajusalu S, Huentelman M, Ramsey K, Naymik M, Narayanan V, Veeraraghavan N, Billings P, Reese MG, Yandell M, Kingsmore SF.

Genome Med. 2021 Oct 14;13(1):153. doi: 10.1186/s13073-021-00965-0. ABSTRACT BACKGROUND: Clinical interpretation of genetic variants in the context of the patient’s phenotype is becoming the largest component of cost and time expenditure for genome-based diagnosis of rare genetic diseases. Artificial intelligence (AI) holds promise to greatly simplify and speed genome interpretation by integrating predictive methods with the growing knowledge of genetic disease. Here we assess the diagnostic performance of Fabric GEM, a new, AI-based, clinical decision support tool for expediting genome interpretation. METHODS: We benchmarked GEM in a retrospective cohort of 119 probands, mostly NICU infants, diagnosed with rare genetic diseases, who received whole-genome or whole-exome sequencing (WGS, WES). We replicated our analyses in a separate cohort of 60 cases collected from five academic medical centers. For comparison, we also analyzed these cases with current state-of-the-art variant prioritization tools. Included in the comparisons were trio, duo, and singleton cases. Variants underpinning diagnoses spanned diverse modes of inheritance and types, including structural variants (SVs). Patient phenotypes were extracted from clinical notes by two means: manually and using an automated clinical natural language processing (CNLP) tool. Finally, 14 previously unsolved cases were reanalyzed. RESULTS: GEM ranked over 90% of the causal genes among the top or second candidate and prioritized for review a median of 3 candidate genes per case, using either manually curated or CNLP-derived phenotype descriptions. Ranking of trios and duos was unchanged when analyzed as singletons. In 17 of 20 cases with diagnostic SVs, GEM identified the causal SVs as the top candidate and in 19/20 within the top five, irrespective of whether SV calls were provided or inferred ab initio by GEM using its own internal SV detection algorithm. GEM showed similar performance in absence of parental genotypes. Analysis of 14 previously unsolved cases resulted in a novel finding for one case, candidates ultimately not advanced upon manual review for 3 cases, and no new findings for 10 cases. CONCLUSIONS: GEM enabled diagnostic interpretation inclusive of all variant types through automated nomination of a very short list of candidate genes and disorders for final review and reporting. In combination with deep phenotyping by CNLP, GEM enables substantial automation of genetic disease diagnosis, potentially decreasing cost and expediting case review. PMID:34645491 | DOI:10.1186/s13073-021-00965-0

October 14, 2021
Rare Disease

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. ABSTRACT 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. PMID:34622282 | DOI:10.1093/hmg/ddab296

October 8, 2021
Neurogenomics

YY1: A New Gene for Childhood Onset Dystonia with Prominent Oromandibular-Laryngeal Involvement?

Ferng A, Thulin P, Walsh E, Weissbrod PA, Friedman J.

Mov Disord. 2021 Oct 7. doi: 10.1002/mds.28813. Online ahead of print. NO ABSTRACT PMID:34618373 | DOI:10.1002/mds.28813

October 8, 2021
Gene DiscoveryNeurogenomics

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. ABSTRACT 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. PMID:34611728 | DOI:10.1007/s00787-021-01883-7

October 6, 2021
Neurogenomics

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. ABSTRACT 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. PMID:34605855 | DOI:10.1093/brain/awab369

October 5, 2021
Neurogenomics

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. ABSTRACT 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. PMID:34587489 | DOI:10.1016/j.ajhg.2021.09.005

September 30, 2021
Neurogenomics

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. ABSTRACT 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.). PMID:34587386 | DOI:10.1056/NEJMoa2033911

September 30, 2021
Neurogenomics

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