Publications by authors named "Federico Zara"

252 Publications

A case of Fibrodysplasia Ossificans Progressiva associated with a novel variant of the ACVR1 gene.

Mol Genet Genomic Med 2021 Aug 4:e1774. Epub 2021 Aug 4.

Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Sciences (DINOGMI), University of Genoa, Genoa, Italy.

Background: Fibrodysplasia Ossificans Progressiva (FOP) is a rare autosomal dominant disease characterized by congenital malformation of the great toes and progressive heterotopic ossification of soft tissues leading to cumulative disability. The genetic cause of FOP are mutations in the ACVR1 gene that encodes a type I receptor of Bone Morphogenetic Proteins. The most recurrent mutation in FOP patients is R206H affecting the Glycine-Serine rich domain and causing the hyper-activation of the receptor and the responsivity to the non-canonical ligand, Activin A. In the present study, we described a 3-years old child with early and highly suggestive clinical features of FOP who was found negative for the recurrent p.R206H substitution.

Methods: Molecular screening of the whole ACVR1 coding sequence and functional characterization in transfection-based assays.

Results And Conclusions: We identified a novel, de novo variant in the fifth ACVR1 coding exon (NM_001111067.4:c.772A>T; NP_001104537.1:p.(R258W)). This substitution, never reported in association with FOP, affects a conserved arginine residue in the kinase domain of the protein. In silico analysis predicted the pathogenicity of this substitution, demonstrated by in vitro assays showing that the p.R258W ACVR1 mutated receptor acquires the ability to transduce the aberrant Activin A-mediated signaling, as observed for the gene variants associated with FOP.
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http://dx.doi.org/10.1002/mgg3.1774DOI Listing
August 2021

Neuromuscular and Neuroendocrinological Features Associated With -Related Arthrogryposis Multiplex Congenita in a Sicilian Family: A Case Report.

Front Neurol 2021 12;12:704747. Epub 2021 Jul 12.

Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.

Wieacker-Wolff syndrome (WWS) is an X-linked Arthrogryposis Multiplex Congenita (AMC) disorder associated with broad neurodevelopmental impairment. The genetic basis of WWS lies in hemizygous pathogenic variants in , encoding a C4H2 type zinc-finger nuclear factor abundantly expressed in the developing human brain. The main clinical features described in WWS families carrying pathogenic variants encompass having a short stature, microcephaly, birth respiratory distress, arthrogryposis, hypotonia, distal muscle weakness, and broad neurodevelopmental delay. We hereby report a Sicilian family with a boy clinically diagnosed with WWS and genetically investigated with exome sequencing (ES), leading to the identification of a c.593G>A (p. R198Q) hemizygous pathogenic variant in the gene. During the first year of life, the onset of central hypoadrenalism led to recurrent hypoglycemic events, which likely contributed to seizure susceptibility. Also, muscle biopsy studies confirmed a pathology of the muscle tissue and revealed peculiar abnormalities of the neuromuscular junction. In conclusion, we expand the phenotypic spectrum of the WWS-related neurodevelopmental disorders and discuss the role of in the context of the potential neuroendocrinological and neuromuscular features associated with this condition.
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http://dx.doi.org/10.3389/fneur.2021.704747DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8313121PMC
July 2021

New phenotype caused by POMGNT2 mutations.

BMJ Case Rep 2021 Jul 22;14(7). Epub 2021 Jul 22.

Pediatrics and Neonatology Department, Ospedale Maggiore di Modica, Nino Baglieri, ASP Ragusa, Ragusa, Sicilia, Italy.

We present a case report about a Moroccan 3-year-old girl, with an intermediate phenotype of muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A, 8 form. We performed clinical and instrumental evaluation, muscle biopsy, genetic screening of 59 genes for different cerebral malformations, follow-up and review of literature. After investigations, we identified an intermediate new phenotype between the severe and mild form, characterised by significant malformations of the cortex with myopatic symptoms, this increases the genotype-phenotype correlation knowledge about POMGNT2 gene mutations. New homozygous missense mutation on POMGNT2 (c.511 G>A, p.Asp171Asn, rs768063378) was detected.
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http://dx.doi.org/10.1136/bcr-2021-242358DOI Listing
July 2021

Role of Common Genetic Variants for Drug-Resistance to Specific Anti-Seizure Medications.

Front Pharmacol 2021 9;12:688386. Epub 2021 Jun 9.

Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.

Resistance to anti-seizure medications (ASMs) presents a significant hurdle in the treatment of people with epilepsy. Genetic markers for resistance to individual ASMs could support clinicians to make better-informed choices for their patients. In this study, we aimed to elucidate whether the response to individual ASMs was associated with common genetic variation. A cohort of 3,649 individuals of European descent with epilepsy was deeply phenotyped and underwent single nucleotide polymorphism (SNP)-genotyping. We conducted genome-wide association analyses (GWASs) on responders to specific ASMs or groups of functionally related ASMs, using non-responders as controls. We performed a polygenic risk score (PRS) analyses based on risk variants for epilepsy and neuropsychiatric disorders and ASM resistance itself to delineate the polygenic burden of ASM-specific drug resistance. We identified several potential regions of interest but did not detect genome-wide significant loci for ASM-specific response. We did not find polygenic risk for epilepsy, neuropsychiatric disorders, and drug-resistance associated with drug response to specific ASMs or mechanistically related groups of ASMs. This study could not ascertain the predictive value of common genetic variants for ASM responder status. The identified suggestive loci will need replication in future studies of a larger scale.
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http://dx.doi.org/10.3389/fphar.2021.688386DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8220970PMC
June 2021

The first case of mosaic MNX1 mutation in an adult female with features of Currarino syndrome.

Birth Defects Res 2021 Jun 22. Epub 2021 Jun 22.

UOC Genetica Medica, Istituto Giannina Gaslini, Genoa, Italy.

Background: Currarino syndrome (CS) is a rare genetic condition characterized by the association of three major clinical signs: anorectal malformation (ARM), sacro-coccygeal bone defects, and presacral mass. Different kinds of ARM can be present such as anteriorly placed anus, imperforate anus, anorectal stenosis, rectal duplication, and fistulae. The presacral mass can be a benign teratoma, a dermoid or neurenteric cyst, anterior meningocele or hamartoma. Females are more frequently affected and usually present with associated gynecologic and urinary tract problems. CS is considered an autosomal dominant trait, with reduced penetrance and variable expressivity. CS is associated with mutations in the MNX1 gene (motor neuron and pancreas homeobox-1, previously known as HLXB9) mapped to chromosome 7q36. Heterozygous loss-of-function mutations in the coding sequence of MNX1 gene have been reported in nearly all familial CS cases and in approximately 30% of CS sporadic patients.

Case: Here, we present the case of a woman with features of CS carrying a mosaic mutation in the coding region of MNX1 gene. This is the only reported case of a CS diagnosis in which the mutation is present in less than 50% of cells.

Conclusion: The lower detection rate of MNX1 mutations in sporadic cases could similarly be explained by somatic mosaicism, mutations occurring outside the coding regions, or genetic heterogeneity.
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http://dx.doi.org/10.1002/bdr2.1936DOI Listing
June 2021

Reply to Braun et al. "Novel bathing epilepsy in a patient with 2q22.3q23.2 deletion".

Seizure 2021 Jun 9;91:112-113. Epub 2021 Jun 9.

Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, Italy; Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.

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http://dx.doi.org/10.1016/j.seizure.2021.06.001DOI Listing
June 2021

KCNT1-related epilepsies and epileptic encephalopathies: phenotypic and mutational spectrum.

Brain 2021 Jun 11. Epub 2021 Jun 11.

Pediatric Neurology Department, Lyon University Hospital, 69500 Bron, France.

Variants in KCNT1, encoding a sodium-gated potassium channel (subfamily T member 1), have been associated with a spectrum of epilepsies and neurodevelopmental disorders. These range from familial autosomal dominant or sporadic sleep-related hypermotor epilepsy ((AD)SHE) to epilepsy of infancy with migrating focal seizures (EIMFS) and include developmental and epileptic encephalopathies (DEE). This study aims to provide a comprehensive overview of the phenotypic and genotypic spectrum of KCNT1 mutation-related epileptic disorders in 248 individuals, including 66 unpreviously published and 182 published cases, the largest cohort reported so far. Four phenotypic groups emerged from our analysis: i) EIMFS (152 individuals, 33 previously unpublished); ii) DEE other than EIMFS (non-EIMFS DEE) (37 individuals, 17 unpublished); iii) (AD)SHE (53 patients, 14 unpublished); iv) other phenotypes (6 individuals, 2 unpublished). In our cohort of 66 new cases, the most common phenotypic features were: a) in EIMFS, heterogeneity of seizure types, including epileptic spasms, epilepsy improvement over time, no epilepsy-related deaths; b) in non-EIMFS DEE, possible onset with West syndrome, occurrence of atypical absences, possible evolution to DEE with SHE features; one case of sudden unexplained death in epilepsy (SUDEP); c) in (AD)SHE, we observed a high prevalence of drug-resistance, although seizure frequency improved with age in some individuals, appearance of cognitive regression after seizure onset in all patients, no reported severe psychiatric disorders, although behavioural/psychiatric comorbidities were reported in about 50% of the patients, SUDEP in one individual; d) other phenotypes in individuals with mutation of KCNT1 included temporal lobe epilepsy, and epilepsy with tonic-clonic seizures and cognitive regression. Genotypic analysis of the whole cohort of 248 individuals showed only missense mutations and one inframe deletion in KCNT1. Although the KCNT1 mutations in affected individuals were seen to be distributed among the different domains of the KCNT1 protein, genotype-phenotype considerations showed many of the (AD)SHE-associated mutations to be clustered around the RCK2 domain in the C-terminus, distal to the NADP domain. Mutations associated with EIMFS/non-EIMFS DEE did not show a particular pattern of distribution in the KCNT1 protein. Recurrent KCNT1 mutations were seen to be associated with both severe and less severe phenotypes. Our study further defines and broadens the phenotypic and genotypic spectrums of KCNT1-related epileptic conditions and emphasizes the increasingly important role of this gene in the pathogenesis of early onset DEEs as well as in focal epilepsies, namely (AD)SHE.
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http://dx.doi.org/10.1093/brain/awab219DOI Listing
June 2021

Clinical and Genetic Features in Patients With Reflex Bathing Epilepsy.

Neurology 2021 Jun 2. Epub 2021 Jun 2.

Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy.

Objective: To describe the clinical and genetic findings in a cohort of subjects with bathing epilepsy, a rare form of reflex epilepsy.

Methods: We investigated by Sanger and targeted re-sequencing the gene in 12 individuals from 10 different families presenting with seizures primarily triggered by bathing or showering. Additional twelve subjects with hot-water epilepsy were also screened.

Results: In all families with bathing epilepsy we identified 8 distinct pathogenic or likely pathogenic variants and 2 variants of unknown significance in , nine of which are . Conversely, none of the subjects with hot-water epilepsy displayed variants. In mutated subjects, seizures were typically triggered by showering or bathing regardless of the water temperature. Additional triggers included fingernail-clipping, hair-cutting, or watching someone take a shower. Non-provoked seizures and a variable degree of developmental delay were also common.

Conclusion: bathing epilepsy is genetically distinct reflex epilepsy mainly caused by mutations.
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http://dx.doi.org/10.1212/WNL.0000000000012298DOI Listing
June 2021

Molecular Genetics in Neuroblastoma Prognosis.

Children (Basel) 2021 May 29;8(6). Epub 2021 May 29.

Department of Pathology, IRCCS Istituto Giannina Gaslini, 16147 Genova, Italy.

In recent years, much research has been carried out to identify the biological and genetic characteristics of the neuroblastoma (NB) tumor in order to precisely define the prognostic subgroups for improving treatment stratification. This review will describe the major genetic features and the recent scientific advances, focusing on their impact on diagnosis, prognosis, and therapeutic solutions in NB clinical management.
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http://dx.doi.org/10.3390/children8060456DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8226597PMC
May 2021

Partial Rescue of F508del-CFTR Stability and Trafficking Defects by Double Corrector Treatment.

Int J Mol Sci 2021 May 17;22(10). Epub 2021 May 17.

U.O.C. Genetica Medica, IRCCS Istituto Giannina Gaslini, 16147 Genova, Italy.

Deletion of phenylalanine at position 508 (F508del) in the CFTR chloride channel is the most frequent mutation in cystic fibrosis (CF) patients. F508del impairs the stability and folding of the CFTR protein, thus resulting in mistrafficking and premature degradation. F508del-CFTR defects can be overcome with small molecules termed correctors. We investigated the efficacy and properties of VX-445, a newly developed corrector, which is one of the three active principles present in a drug (Trikafta/Kaftrio) recently approved for the treatment of CF patients with F508del mutation. We found that VX-445, particularly in combination with type I (VX-809, VX-661) and type II (corr-4a) correctors, elicits a large rescue of F508del-CFTR function. In particular, in primary bronchial epithelial cells of CF patients, the maximal rescue obtained with corrector combinations including VX-445 was close to 60-70% of CFTR function in non-CF cells. Despite this high efficacy, analysis of ubiquitylation, resistance to thermoaggregation, protein half-life, and subcellular localization revealed that corrector combinations did not fully normalize F508del-CFTR behavior. Our study indicates that it is still possible to further improve mutant CFTR rescue with the development of corrector combinations having maximal effects on mutant CFTR structural and functional properties.
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http://dx.doi.org/10.3390/ijms22105262DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8156943PMC
May 2021

Assessing the role of rare genetic variants in drug-resistant, non-lesional focal epilepsy.

Ann Clin Transl Neurol 2021 Jul 21;8(7):1376-1387. Epub 2021 May 21.

Université de Montréal, Montreal, Canada.

Objective: Resistance to antiseizure medications (ASMs) is one of the major concerns in the treatment of epilepsy. Despite the increasing number of ASMs available, the proportion of individuals with drug-resistant epilepsy remains unchanged. In this study, we aimed to investigate the role of rare genetic variants in ASM resistance.

Methods: We performed exome sequencing of 1,128 individuals with non-familial non-acquired focal epilepsy (NAFE) (762 non-responders, 366 responders) and were provided with 1,734 healthy controls. We undertook replication in a cohort of 350 individuals with NAFE (165 non-responders, 185 responders). We performed gene-based and gene-set-based kernel association tests to investigate potential enrichment of rare variants in relation to drug response status and to risk for NAFE.

Results: We found no gene or gene set that reached genome-wide significance. Yet, we identified several prospective candidate genes - among them DEPDC5, which showed a potential association with resistance to ASMs. We found some evidence for an enrichment of truncating variants in dominant familial NAFE genes in our cohort of non-familial NAFE and in association with drug-resistant NAFE.

Interpretation: Our study identifies potential candidate genes for ASM resistance. Our results corroborate the role of rare variants for non-familial NAFE and imply their involvement in drug-resistant epilepsy. Future large-scale genetic research studies are needed to substantiate these findings.
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http://dx.doi.org/10.1002/acn3.51374DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8283173PMC
July 2021

Biallelic variants in HPDL cause pure and complicated hereditary spastic paraplegia.

Brain 2021 Jun;144(5):1422-1434

Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.

Human 4-hydroxyphenylpyruvate dioxygenase-like (HPDL) is a putative iron-containing non-heme oxygenase of unknown specificity and biological significance. We report 25 families containing 34 individuals with neurological disease associated with biallelic HPDL variants. Phenotypes ranged from juvenile-onset pure hereditary spastic paraplegia to infantile-onset spasticity and global developmental delays, sometimes complicated by episodes of neurological and respiratory decompensation. Variants included bona fide pathogenic truncating changes, although most were missense substitutions. Functionality of variants could not be determined directly as the enzymatic specificity of HPDL is unknown; however, when HPDL missense substitutions were introduced into 4-hydroxyphenylpyruvate dioxygenase (HPPD, an HPDL orthologue), they impaired the ability of HPPD to convert 4-hydroxyphenylpyruvate into homogentisate. Moreover, three additional sets of experiments provided evidence for a role of HPDL in the nervous system and further supported its link to neurological disease: (i) HPDL was expressed in the nervous system and expression increased during neural differentiation; (ii) knockdown of zebrafish hpdl led to abnormal motor behaviour, replicating aspects of the human disease; and (iii) HPDL localized to mitochondria, consistent with mitochondrial disease that is often associated with neurological manifestations. Our findings suggest that biallelic HPDL variants cause a syndrome varying from juvenile-onset pure hereditary spastic paraplegia to infantile-onset spastic tetraplegia associated with global developmental delays.
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http://dx.doi.org/10.1093/brain/awab041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8219359PMC
June 2021

Biallelic Variants in Associated with Microphthalmia and Coloboma Spectrum.

Int J Mol Sci 2021 Apr 25;22(9). Epub 2021 Apr 25.

Department of Human Pathology in Adult and Developmental Age "Gaetano Barresi, Unit of Pediatric Nephrology and Dialysis, University of Messina, Via Consolare Valeria 1, 98124 Messina, Italy.

Microphthalmia, anophthalmia, and coloboma (MAC) are a group of congenital eye anomalies that can affect one or both eyes. Patients can present one or a combination of these ocular abnormalities in the so called "MAC spectrum". The gene encodes the kinesin-like protein Kif17, a microtubule-based, ATP-dependent, motor protein that is pivotal for outer segment development and disc morphogenesis in different animal models, including mice and zebrafish. In this report, we describe a Sicilian family with two siblings affected with congenital coloboma, microphthalmia, and a mild delay of motor developmental milestones. Genomic DNA from the siblings and their unaffected parents was sequenced with a clinical exome that revealed compound heterozygous variants in the gene (NM_020816.4: c.1255C > T (p.Arg419Trp); c.2554C > T (p.Arg852Cys)) segregating with the MAC spectrum phenotype of the two affected siblings. Variants were inherited from the healthy mother and father, are present at a very low-frequency in genomic population databases, and are predicted to be deleterious in silico. Our report indicates the potential co-segregation of these biallelic variants with microphthalmia and coloboma, highlighting a potential conserved role of this gene in eye development across different species.
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http://dx.doi.org/10.3390/ijms22094471DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8123208PMC
April 2021

Genotype-Phenotype Correlations in Neurofibromatosis Type 1: A Single-Center Cohort Study.

Cancers (Basel) 2021 Apr 14;13(8). Epub 2021 Apr 14.

Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, 16132 Genoa, Italy.

Neurofibromatosis type 1 (NF1) is a proteiform genetic condition caused by pathogenic variants in and characterized by a heterogeneous phenotypic presentation. Relevant genotype-phenotype correlations have recently emerged, but only few pertinent studies are available. We retrospectively reviewed clinical, instrumental, and genetic data from a cohort of 583 individuals meeting at least 1 diagnostic National Institutes of Health (NIH) criterion for NF1. Of these, 365 subjects fulfilled ≥2 NIH criteria, including 235 pediatric patients. Genetic testing was performed through cDNA-based sequencing, Next Generation Sequencing (NGS), and Multiplex Ligation-dependent Probe Amplification (MLPA). Uni- and multivariate statistical analysis was used to investigate genotype-phenotype correlations. Among patients fulfilling ≥ 2 NIH criteria, causative single nucleotide variants (SNVs) and copy number variations (CNVs) were detected in 267/365 (73.2%) and 20/365 (5.5%) cases. Missense variants negatively correlated with neurofibromas ( = 0.005). Skeletal abnormalities were associated with whole gene deletions ( = 0.05) and frameshift variants ( = 0.006). The c.3721C>T; p.(R1241*) variant positively correlated with structural brain alterations ( = 0.031), whereas Lisch nodules ( = 0.05) and endocrinological disorders ( = 0.043) were associated with the c.6855C>A; p.(Y2285*) variant. We identified novel NF1 genotype-phenotype correlations and provided an overview of known associations, supporting their potential relevance in the implementation of patient management.
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http://dx.doi.org/10.3390/cancers13081879DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8070780PMC
April 2021

Exosomes from Plasma of Neuroblastoma Patients Contain Doublestranded DNA Reflecting the Mutational Status of Parental Tumor Cells.

Int J Mol Sci 2021 Apr 1;22(7). Epub 2021 Apr 1.

IRCCS Giannina Gaslini, 16147 Genova, Italy.

Neuroblastoma (NB) is an aggressive infancy tumor, leading cause of death among preschool age diseases. Here we focused on characterization of exosomal DNA (exo-DNA) isolated from plasma cell-derived exosomes of neuroblastoma patients, and its potential use for detection of somatic mutations present in the parental tumor cells. Exosomes are small extracellular membrane vesicles secreted by most cells, playing an important role in intercellular communications. Using an enzymatic method, we provided evidence for the presence of double-stranded DNA in the NB exosomes. Moreover, by whole exome sequencing, we demonstrated that NB exo-DNA represents the entire exome and that it carries tumor-specific genetic mutations, including those occurring on known oncogenes and tumor suppressor genes in neuroblastoma (, , , , , , and ). NB exo-DNA can be useful to identify variants responsible for acquired resistance, such as mutations of , , and / genes that appear in relapsed patients. The possibility to isolate and to enrich NB derived exosomes from plasma using surface markers, and the quick and easy extraction of exo-DNA, gives this methodology a translational potential in the clinic. Exo-DNA can be an attractive non-invasive biomarker for NB molecular diagnostic, especially when tissue biopsy cannot be easily available.
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http://dx.doi.org/10.3390/ijms22073667DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8036333PMC
April 2021

Real-life survey of pitfalls and successes of precision medicine in genetic epilepsies.

J Neurol Neurosurg Psychiatry 2021 Apr 26. Epub 2021 Apr 26.

Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, and Chalfont Centre for Epilepsy, Gerrard Cross, UK

Objective: The term 'precision medicine' describes a rational treatment strategy tailored to one person that reverses or modifies the disease pathophysiology. In epilepsy, single case and small cohort reports document nascent precision medicine strategies in specific genetic epilepsies. The aim of this multicentre observational study was to investigate the deeper complexity of precision medicine in epilepsy.

Methods: A systematic survey of patients with epilepsy with a molecular genetic diagnosis was conducted in six tertiary epilepsy centres including children and adults. A standardised questionnaire was used for data collection, including genetic findings and impact on clinical and therapeutic management.

Results: We included 293 patients with genetic epilepsies, 137 children and 156 adults, 162 females and 131 males. Treatment changes were undertaken because of the genetic findings in 94 patients (32%), including rational precision medicine treatment and/or a treatment change prompted by the genetic diagnosis, but not directly related to known pathophysiological mechanisms. There was a rational precision medicine treatment for 56 patients (19%), and this was tried in 33/56 (59%) and was successful (ie, >50% seizure reduction) in 10/33 (30%) patients. In 73/293 (25%) patients there was a treatment change prompted by the genetic diagnosis, but not directly related to known pathophysiological mechanisms, and this was successful in 24/73 (33%).

Significance: Our survey of clinical practice in specialised epilepsy centres shows high variability of clinical outcomes following the identification of a genetic cause for an epilepsy. Meaningful change in the treatment paradigm after genetic testing is not yet possible for many people with epilepsy. This systematic survey provides an overview of the current application of precision medicine in the epilepsies, and suggests the adoption of a more considered approach.
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http://dx.doi.org/10.1136/jnnp-2020-325932DOI Listing
April 2021

Temporal-parietal-occipital epilepsy in GEFS+ associated with SCN1A mutation.

Epileptic Disord 2021 Apr;23(2):397-401

Department of Neuroscience, Reproductive and Odontostomatological Sciences, Federico II University, Napoli, Italy.

Most families with genetic epilepsy with febrile seizures plus show a mutation in the sodium channel alpha 1 subunit gene, however, but there is much phenotypic heterogeneity and focal epilepsy remains relatively rare. Here, we report a family with electroclinical features indicative of temporal-parietal-occipital carrefour epilepsy with common occurrence of post-ictal migraine. We studied a four-generation family including nine affected subjects by means of EEG and MRI. Genetic testing was performed by targeted re-sequencing (gene panel). In most patients, seizure semiology included cognitive, autonomic, and emotional symptoms, eventually evolving towards sensory visual phenomena. Focal sensory vestibular seizures and changes in body perception were also reported in some cases. Post-ictal migraine was common, occurring in five out of the six (83%) epilepsy patients. A missense mutation (c.1130 G>A; p.R377Q) affecting the S5-S6 segment (pore region) of the sodium channel alpha 1 subunit was identified in all affected and four unaffected subjects. Temporal-parietal-occipital carrefour epilepsy is part of the genetic epilepsy with febrile seizures plus spectrum. The electroclinical features in this family support the involvement of a genetically impaired neural network. High prevalence of post-ictal migraine suggests the role of posterior brain areas in the clinical expression of this gene defect.
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http://dx.doi.org/10.1684/epd.2021.1266DOI Listing
April 2021

Italian cohort of Lafora disease: Clinical features, disease evolution, and genotype-phenotype correlations.

J Neurol Sci 2021 May 20;424:117409. Epub 2021 Mar 20.

Unit of Medical Genetics, IRCCS Istituto Giannina Gaslini, Genova, Italy; Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, Università degli Studi di Genova, Genova, Italy.

Background: Lafora disease (LD) is characterized by progressive myoclonus, refractory epilepsy, and cognitive deterioration. This complex neurodegenerative condition is caused by pathogenic variants in EPM2A/EPM2B genes, encoding two essential glycogen metabolism enzymes known as laforin and malin. Long-term follow-up data are lacking. We describe the clinical features and genetic findings of a cohort of 26 Italian patients with a long clinical follow-up.

Methods: Patients with EPM2A/EPM2B pathogenic variants were identified by direct gene sequencing or gene panels with targeted re-sequencing. Disease progression, motor functions, and mental performance were assessed by a simplified disability scale. Spontaneous/action myoclonus severity was scored by the Magaudda Scale.

Results: Age range was 12.2-46.2 years (mean:25.53 ± 9.14). Age at disease onset ranged from 10 to 22 years (mean:14.04 ± 2.62). The mean follow-up period was 11.48 ± 7.8 years. Twelve out of the 26 (46%) patients preserved walking ability and 13 (50%) maintained speech. A slower disease progression with preserved ambulation and speech after ≥4 years of follow-up was observed in 1 (11%) out of the 9 (35%) EPM2A patients and in 6 (35%) out of the 17 (65%) EPM2B patients. Follow-up was >10 years in 7 (41.2%) EPM2B individuals, including two harbouring the homozygous p.(D146N) pathogenic variant.

Conclusions: This study supports an overall worse disease outcome with severe deterioration of ambulation and speech in patients carrying EPM2A mutations. However, the delayed onset of disabling symptoms observed in the EPM2B subjects harbouring the p.(D146N) pathogenic variant suggests that the underlying causative variant may still influence LD severity.
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http://dx.doi.org/10.1016/j.jns.2021.117409DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8166462PMC
May 2021

Genotype-phenotype correlations in patients with de novo pathogenic variants.

Neurol Genet 2020 Dec 30;6(6):e528. Epub 2020 Nov 30.

Department of Neurosciences (F. Malerba, G.B., E.A., A. Riva, V.S., L.N., C. Minetti, F.Z., P.S.), Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, Università degli Studi di Genova; Pediatric Neurology and Muscular Diseases Unit (F. Malerba, G.B., F. Marchese, E.A., A. Riva, M.S.V., V.S., C. Minetti, P.S.), IRCCS Istituto G. Gaslini; Center for Synaptic Neuroscience and Technology ([email protected]) (G.A., L.M., F.B.), Istituto Italiano di Tecnologia; Department of Experimental Medicine (G.A.), Università degli Studi di Genova; Laboratory of Human Genetics (E.G.); Unit of Medical Genetics (F. Madia, F.Z.), IRCCS Istituto G. Gaslini, Genova, Italy; Child Neurology and Neurorehabilitation Unit (M.A.), Department of Pediatrics, Central Hospital of Bolzano, Bolzano; Child Neurology and Psychiatry Unit (L.G., P.A., P.M.), ASST Spedali Civili, Brescia; Neurology Unit (M. Trivisano, N.S.), Department of Neuroscience, Bambino Gesù Children's Hospital, IRCCS, Roma; Child Neurology Unit (A. Russo, G.G.), IRCCS, Institute of Neurological Sciences of Bologna; Child Neuropsychiatry Unit (F.R.), U.O.N.P.I.A. ASST-Rhodense, Rho, Milano; Neurology Unit and Laboratories (T.P.), A. Meyer Children's Hospital, Firenze; Child Neurology and Psychiatric Unit (C. Marini), Pediatric Hospital G. Salesi, United Hospital of Ancona; Child Neuropsychiatry Unit (M.M.M., L.N.), IRCCS Istituto G. Gaslini, Genova; Department of Pediatric Neuroscience (E.F.), Fondazione IRCCS Istituto Neurologico Carlo Besta; Unit of Genetics of Neurodegenerative and Metabolic Diseases (B. Castellotti), Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano; Department of Child Neuropsychiatry (G.C.), Epilepsy Center, C. Poma Hospital, Mantova; Fondazione Poliambulanza Brescia (G.C.); Epilepsy Center (A.C.), Department of Neuroscience, Reproductive and Odontostomatological Sciences, Università degli Studi di Napoli Federico II, Napoli; Department of Pediatrics (A.V.), University of Perugia; Section of Pharmacology (F. Miceli, M. Taglialatela), Department of Neuroscience, Reproductive and Odontostomatological Sciences, Università degli Studi di Napoli Federico II, Napoli; IRCCS Ospedale Policlinico San Martino (L.M., F.B.), Genova, Italy; Division of Pediatric Neurology (M.R.C.), Saint-Luc University Hospital, and Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain, Brussels, Belgium; Department of Epilepsy Genetics and Personalized Treatment (K.M.J., R.S.M.), The Danish Epilepsy Center Filadelfia, Dianalund, Denmark; Institute for Regional Health Services (K.M.J., R.S.M.), University of Southern Denmark, Odense, Denmark; Department of Neurology (B. Ceulemans, S.W.), University Hospital Antwerp; Applied & Translational Neurogenomics Group (S.W.), VIB-Center for Molecular Neurology; Laboratory of Neurogenetics (S.W.), Institute Born-Bunge, University of Antwerp, Belgium; and Department of Life and Environmental Sciences (L.M.), Polytechnic University of Marche, Ancona, Italy.

Objective: Early identification of de novo variants in patients with epilepsy raises prognostic issues toward optimal management. We analyzed the clinical and genetic information from a cohort of patients with de novo pathogenic variants to dissect genotype-phenotype correlations.

Methods: Patients with de novo pathogenic variants were identified from Italy, Denmark, and Belgium. Atomic resolution Kv7.2 structures were also generated using homology modeling to map the variants.

Results: We included 34 patients with a mean age of 4.7 years. Median seizure onset was 2 days, mainly with focal seizures with autonomic signs. Twenty-two patients (65%) were seizure free at the mean age of 1.2 years. More than half of the patients (17/32) displayed severe/profound intellectual disability; however, 4 (13%) of them had a normal cognitive outcome.A total of 28 de novo pathogenic variants were identified, most missense (25/28), and clustered in conserved regions of the protein; 6 variants recurred, and 7 were novel. We did not identify a relationship between variant position and seizure offset or cognitive outcome in patients harboring missense variants. Besides, recurrent variants were associated with overlapping epilepsy features but also variable evolution regarding the intellectual outcome.

Conclusions: We highlight the complexity of variant interpretation to assess the impact of a class of de novo mutations. Genetic modifiers could be implicated, but the study paradigms to successfully address the impact of each single mutation need to be developed.
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http://dx.doi.org/10.1212/NXG.0000000000000528DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7803337PMC
December 2020

Musculoskeletal Features without Ataxia Associated with a Novel de novo Mutation in Impairing the Voltage Sensitivity of Kv1.1 Channel.

Biomedicines 2021 Jan 14;9(1). Epub 2021 Jan 14.

Paediatric Neurology and Neuromuscular Disorders Unit, IRCCS Institute "G. Gaslini", 80131 Genoa, Italy.

The gene encodes the α subunit of the voltage-gated Kv1.1 potassium channel that critically regulates neuronal excitability in the central and peripheral nervous systems. Mutations in have been classically associated with episodic ataxia type 1 (EA1), a movement disorder triggered by physical and emotional stress. Additional features variably reported in recent years include epilepsy, myokymia, migraine, paroxysmal dyskinesia, hyperthermia, hypomagnesemia, and cataplexy. Interestingly, a few individuals with neuromyotonia, either isolated or associated with skeletal deformities, have been reported carrying variants in the S2-S3 transmembrane segments of Kv1.1 channels in the absence of any other symptoms. Here, we have identified by whole-exome sequencing a novel de novo variant, T268K, in in a boy displaying recurrent episodes of neuromyotonia, muscle hypertrophy, and skeletal deformities. Through functional analysis in heterologous cells and structural modeling, we show that the mutation, located at the extracellular end of the S3 helix, causes deleterious effects, disrupting Kv1.1 function by altering the voltage dependence of activation and kinetics of deactivation, likely due to abnormal interactions with the voltage sensor in the S4 segment. Our study supports previous evidence suggesting that specific residues within the S2 and S3 segments of Kv1.1 result in a distinctive phenotype with predominant musculoskeletal presentation.
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http://dx.doi.org/10.3390/biomedicines9010075DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7829709PMC
January 2021

Basal Ganglia Dysmorphism in Patients With Aicardi Syndrome.

Neurology 2021 03 4;96(9):e1319-e1333. Epub 2020 Dec 4.

From the Department of Brain and Behavioural Neurosciences (S.M., A.P., M. Formica, S.O.) and Department of Public Health Experimental and Forensic Medicine, Biostatistic and Clinical Epidemiology Unit (P. Borrelli), University of Pavia; Pediatric Neurology Unit (S.M., M. Mastrangelo, P.V.), V. Buzzi Children's Hospital, Milan; Department of Neuroradiology (A.P.), Child Neurology and Psychiatry Unit (R.B., V.D.G., S.O.), and Department of Internal Medicine and Therapeutics, Member of the ERN EpiCARE, University of Pavia and Clinical Trial Center (E.P.), IRCCS Mondino Foundation Pavia; Neuroimaging Lab (F.A.) and Neuropsychiatry and Neurorehabilitation Unit (R.R.), Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco; Child Neuropsychiatric Unit (P.A., L.G.), Civilian Hospital, Brescia; Scientific Institute (P. Bonanni, A.D., E.O.), IRCCS E. Medea, Epilepsy and Clinical Neurophysiology Unit, Conegliano, Treviso; UOC Child Neuropsychiatry (B.D.B., F.D.), Department of Surgical Sciences, Dentistry, Gynecology and Pediatrics, University of Verona, Italy; Département de Neurologie Pédiatrique (N.D.), Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Belgium; AdPueriVitam (O.D.), Antony; Service d'Explorations Fonctionnelles (S.G.), Centre de Médecine du Sommeil, l'Hôpital Àntoine Béclère, AP-HP, Clamart; Pediatrics Departement (S.G.), André-Grégoire Hospital, Centre Hospitalier Inter Communal, Montreuil, France; Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department (R.G., M. Montomoli, M.C.) and Radiology (M. Mortilla), A. Meyer Children's Hospital, Member of the ERN EpiCARE, University of Florence; IRCCS Stella Maris Foundation (R.G.), Pisa; Child Neuropsychiatry Unit, Epilepsy Center (F.L.B., A.V.), San Paolo Hospital, Department of Health Sciences, Università degli Studi di Milano, Milan; Child Neurology, NESMOS Department (P.P.), Faculty of Medicine & Psychology, Sant'Andrea Hospital, Sapienza University, Rome; Department of Neuroradiology (L.P.), Pediatric Neuroradiology Section, ASST Spedali Civili, Brescia; Pediatric Neuroradiology Unit (M.S.), IRCCS Istituto Giannina Gaslini, Genova; Neurology Unit, Department of Neuroscience, Member of the ERN EpiCARE (F.V.), Oncological Neuroradiology Unit, Department of Imaging, IRCCS (G.C.), and Department of Neuroscience and Neurorehabilitation (A.F.), Bambino Gesù Children's Hospital, Rome, Italy; Institut Imagine (N.B.-B.), Université Paris Descartes-Sorbonne Paris Cités; Pediatric Neurology (N.B.-B., I.D.), Necker Enfants Malades Hospital, Member of the ERN EpiCARE, Assistance Publique-Hôpitaux de Paris; INSERM UMR-1163 (N.B.-B., A. Arzimanoglou), Embryology and Genetics of Congenital Malformations, France; UOC Neurochirurgia (A. Accogli, V.C.), Pediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa (F.Z.), and Laboratory of Neurogenetics and Neuroscience, IRCCS (F.Z.), Istituto Giannina Gaslini, Genoa, Italy; Neurochirurgie Pédiatrique (M.B.), Hôpital NEM, Paris, France; Centre Médico-Chirurgical des Eaux-Vives (V.C.-V.), Swiss Medical Network, Genève, Switzerland; Neuroradiology Unit (L.C.) and Developmental Neurology Unit (S.D.), Foundation IRCCS C. Besta Neurological Institute, Milan; Service de Génétique (M.D.-F.), AMH2, CHU Reims, UFR de Médecine, Reims, France; Epilepsy Centre-Clinic of Nervous System Diseases (G.d.), Riuniti Hospital, Foggia, Italy; MediClubGeorgia Co Ltd (N.E.), Tbilisi, Georgia; Epilepsy Center (N.E.), Medical Center, Faculty of Medicine, University of Freiburg, Germany; Child and Adolescence Neurology and Psychiatry Unit (E. Fazzi), ASST Civil Hospital, Department of Clinical and Experimental Sciences, University of Brescia; Child Neurology Department (E. Fiorini), Verona, Italy; Service de Genetique Clinique (M. Fradin, P.L., C.Q.), CLAD-Ouest, Hospital Sud, Rennes, France; Child Neurology Unit, Pediatric Department (C.F., C.S.), Azienda USL-IRCCS di Reggio Emilia; Department of Pediatric Neuroscience (T.G., R.S.), Fondazione IRCCS Istituto Neurologico Carlo Besta, Member of the ERN EpiCARE, Milan, Italy; Department of Epilepsy Genetics and Personalized Treatment (K.M.J., R.S.M.), The Danish Epilepsy Centre, Dianalund; Institute for Regional Health Services (K.M.J., R.S.M.), University of Southern Denmark, Odense; Unit of Pediatric Neurology and Pediatric Neurorehabilitation (S.L.), Woman-Mother-Child Department, Lausanne University Hospital CHUV, Switzerland; Unit of Neuroradiology (D.M.), Fondazione CNR/Regione Toscana G. Monasterio, Pisa; Pediatric Neurology Unit and Epilepsy Center (E.R., A.R.), Fatebenefratelli Hospital, Milan, Italy; KJF Klinik Josefinum GmbH (C.U.), Klinik für Kinder und Jugendliche, Neuropädiatrie, Augsburg, Germany; Department of Paediatric Clinical Epileptology, Sleep Disorders and Functional Neurology (A. Arzimanoglou), University Hospitals of Lyon, Coordinator of the ERN EpiCARE, France; and Pediatric Epilepsy Unit, Child Neurology Department (P.V.), Hospital San Juan de Dios, Member of the ERN EpiCARE and Universitat de Barcelona, Spain.

Objective: Aiming to detect associations between neuroradiologic and EEG evaluations and long-term clinical outcome in order to detect possible prognostic factors, a detailed clinical and neuroimaging characterization of 67 cases of Aicardi syndrome (AIC), collected through a multicenter collaboration, was performed.

Methods: Only patients who satisfied Sutton diagnostic criteria were included. Clinical outcome was assessed using gross motor function, manual ability, and eating and drinking ability classification systems. Brain imaging studies and statistical analysis were reviewed.

Results: Patients presented early-onset epilepsy, which evolved into drug-resistant seizures. AIC has a variable clinical course, leading to permanent disability in most cases; nevertheless, some cases presented residual motor abilities. Chorioretinal lacunae were present in 86.56% of our patients. Statistical analysis revealed correlations between MRI, EEG at onset, and clinical outcome. On brain imaging, 100% of the patients displayed corpus callosum malformations, 98% cortical dysplasia and nodular heterotopias, and 96.36% intracranial cysts (with similar rates of 2b and 2d). As well as demonstrating that posterior fossa abnormalities (found in 63.63% of cases) should also be considered a common feature in AIC, our study highlighted the presence (in 76.36%) of basal ganglia dysmorphisms (never previously reported).

Conclusion: The AIC neuroradiologic phenotype consists of a complex brain malformation whose presence should be considered central to the diagnosis. Basal ganglia dysmorphisms are frequently associated. Our work underlines the importance of MRI and EEG, both for correct diagnosis and as a factor for predicting long-term outcome.

Classification Of Evidence: This study provides Class II evidence that for patients with AIC, specific MRI abnormalities and EEG at onset are associated with clinical outcomes.
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http://dx.doi.org/10.1212/WNL.0000000000011237DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8055324PMC
March 2021

Dual diagnosis in a child with familial SCN8A-related encephalopathy complicated by a 1p13.2 deletion involving NRAS gene.

Neurol Sci 2021 05 17;42(5):2115-2117. Epub 2020 Nov 17.

Department of Translational Medical Sciences, Child Neurology, University of Naples Federico II, Naples, Italy.

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http://dx.doi.org/10.1007/s10072-020-04898-1DOI Listing
May 2021

Brain Organoids as Model Systems for Genetic Neurodevelopmental Disorders.

Front Cell Dev Biol 2020 12;8:590119. Epub 2020 Oct 12.

Medical Genetics Unit, IRCSS Giannina Gaslini Institute, Genoa, Italy.

Neurodevelopmental disorders (NDDs) are a group of disorders in which the development of the central nervous system (CNS) is disturbed, resulting in different neurological and neuropsychiatric features, such as impaired motor function, learning, language or non-verbal communication. Frequent comorbidities include epilepsy and movement disorders. Advances in DNA sequencing technologies revealed identifiable genetic causes in an increasingly large proportion of NDDs, highlighting the need of experimental approaches to investigate the defective genes and the molecular pathways implicated in abnormal brain development. However, targeted approaches to investigate specific molecular defects and their implications in human brain dysfunction are prevented by limited access to patient-derived brain tissues. In this context, advances of both stem cell technologies and genome editing strategies during the last decade led to the generation of three-dimensional (3D) -models of cerebral organoids, holding the potential to recapitulate precise stages of human brain development with the aim of personalized diagnostic and therapeutic approaches. Recent progresses allowed to generate 3D-structures of both neuronal and non-neuronal cell types and develop either whole-brain or region-specific cerebral organoids in order to investigate key brain developmental processes, such as neuronal cell morphogenesis, migration and connectivity. In this review, we summarized emerging methodological approaches in the field of brain organoid technologies and their application to dissect disease mechanisms underlying an array of pediatric brain developmental disorders, with a particular focus on autism spectrum disorders (ASDs) and epileptic encephalopathies.
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http://dx.doi.org/10.3389/fcell.2020.590119DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7586734PMC
October 2020

De novo ARHGEF9 missense variants associated with neurodevelopmental disorder in females: expanding the genotypic and phenotypic spectrum of ARHGEF9 disease in females.

Neurogenetics 2021 03 17;22(1):87-94. Epub 2020 Sep 17.

Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.

Individuals harboring pathogenic variants in ARHGEF9, encoding an essential submembrane protein for gamma-aminobutyric acid (GABA)-ergic synapses named collybistin, show intellectual disability (ID), facial dysmorphism, behavioral disorders, and epilepsy. Only few affected females carrying large chromosomal rearrangements involving ARHGEF9 have been reported so far. Through next-generation sequencing (NGS)-based panels, we identified two single nucleotide variants (SNVs) in ARHGEF9 in two females with neurodevelopmental features. Sanger sequencing revealed that these variants were de novo. The X-inactivation pattern in peripheral blood cells was random. We report the first affected females harboring de novo SNVs in ARHGEF9, expanding the genotypic and phenotypic spectrum of ARHGEF9-related neurodevelopmental disorder in females.
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http://dx.doi.org/10.1007/s10048-020-00622-5DOI Listing
March 2021

Targeting Alternative Splicing as a Potential Therapy for Episodic Ataxia Type 2.

Biomedicines 2020 Sep 5;8(9). Epub 2020 Sep 5.

Department of Life Sciences, University of Trieste, 34127 Trieste, Italy.

Episodic ataxia type 2 (EA2) is an autosomal dominant neurological disorder characterized by paroxysmal attacks of ataxia, vertigo, and nausea that usually last hours to days. It is caused by loss-of-function mutations in , the gene encoding the pore-forming α subunit of P/Q-type voltage-gated Ca channels. Although pharmacological treatments, such as acetazolamide and 4-aminopyridine, exist for EA2, they do not reduce or control the symptoms in all patients. is heavily spliced and some of the identified EA2 mutations are predicted to disrupt selective isoforms of this gene. Modulating splicing of may therefore represent a promising new strategy to develop improved EA2 therapies. Because RNA splicing is dysregulated in many other genetic diseases, several tools, such as antisense oligonucleotides, -splicing, and CRISPR-based strategies, have been developed for medical purposes. Here, we review splicing-based strategies used for genetic disorders, including those for Duchenne muscular dystrophy, spinal muscular dystrophy, and frontotemporal dementia with Parkinsonism linked to chromosome 17, and discuss their potential applicability to EA2.
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http://dx.doi.org/10.3390/biomedicines8090332DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7555146PMC
September 2020

Clinical spectrum and genotype-phenotype correlations in PRRT2 Italian patients.

Eur J Paediatr Neurol 2020 Sep 23;28:193-197. Epub 2020 Jun 23.

Istituto di Ricovero e Cura a Carattere Scientifico, Ospedale Policlinico San Martino, Genoa, Italy; Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy.

Prrt2 is a neuron-specific protein expressed at axonal and pre-synaptic domains, involved in synaptic neurotransmitter release and modulation of intrinsic excitability. Mutations in PRRT2 cause a spectrum of autosomal dominant paroxysmal neurological disorders including epilepsy, movement disorders, and hemiplegic migraine and show incomplete penetrance and variable expressivity. We assessed the diagnostic rate of PRRT2 in a cohort of Italian patients with epilepsy and/or paroxysmal kinesigenic dyskinesia (PKD) and evaluated genotype-phenotype correlations. Clinical data were collected using a structured questionnaire. Twenty-seven out of 55 (49.1%) probands carried PRRT2 heterozygous pathogenic variants, including six previously known genotypes and one novel missense mutation. A family history of epilepsy starting in the first year of life and/or PKD was strongly suggestive of a PRRT2 pathogenic variant. Epilepsy patients harbouring PRRT2 pathogenic variants showed earlier seizure onset and more frequent clusters compared with PRRT2-negative individuals with epilepsy. Moreover, we did also identify individuals with PRRT2 pathogenic variants with atypical age at onset, i.e. childhood-onset epilepsy and infantile-onset PKD. However, the lack of a clear correlation between specific PRRT2 genotypes and clinical manifestations and the high incidence of asymptomatic carriers suggest the involvement of additional factors in modulating expressivity of PRRT2-related disorders. Finally, our study supports the pleiotropic and multifaceted physiological role of PRRT2 gene which is emerging from experimental neuroscience.
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http://dx.doi.org/10.1016/j.ejpn.2020.06.005DOI Listing
September 2020

Loss of Wwox Perturbs Neuronal Migration and Impairs Early Cortical Development.

Front Neurosci 2020 11;14:644. Epub 2020 Jun 11.

Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto "Giannina Gaslini", Genoa, Italy.

Mutations in the gene cause a broad range of ultra-rare neurodevelopmental and brain degenerative disorders, associated with a high likelihood of premature death in animal models as well as in humans. The encoded Wwox protein is a WW domain-containing oxidoreductase that participates in crucial biological processes including tumor suppression, cell growth/differentiation and regulation of steroid metabolism, while its role in neural development is less understood. We analyzed the exomes of a family affected with multiple pre- and postnatal anomalies, including cerebellar vermis hypoplasia, severe neurodevelopmental impairment and refractory epilepsy, and identified a segregating homozygous mutation leading to a premature stop codon. Abnormal cerebral cortex development due to a defective architecture of granular and molecular cell layers was found in the developing brain of a -deficient human fetus from this family. A similar disorganization of cortical layers was identified in rats (carrying a homozygous truncating mutation which disrupts the active Wwox C-terminal domain) investigated at perinatal stages. Transcriptomic analyses of Wwox-depleted human neural progenitor cells showed an impaired expression of a number of neuronal migration-related genes encoding for tubulins, kinesins and associated proteins. These findings indicate that loss of Wwox may affect different cytoskeleton components and alter prenatal cortical development, highlighting a regulatory role of the gene in migrating neurons across different species.
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http://dx.doi.org/10.3389/fnins.2020.00644DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7300205PMC
June 2020

Biallelic MFSD2A variants associated with congenital microcephaly, developmental delay, and recognizable neuroimaging features.

Eur J Hum Genet 2020 11 22;28(11):1509-1519. Epub 2020 Jun 22.

Signature Research Program in Cardiovascular and Metabolic Disorders, Duke-NUS Medical School, Singapore, 169857, Singapore.

Major Facilitator Superfamily Domain containing 2a (MFSD2A) is an essential endothelial lipid transporter at the blood-brain barrier. Biallelic variants affecting function in MFSD2A cause autosomal recessive primary microcephaly 15 (MCPH15, OMIM# 616486). We sought to expand our knowledge of the phenotypic spectrum of MCPH15 and demonstrate the underlying mechanism of inactivation of the MFSD2A transporter. We carried out detailed analysis of the clinical and neuroradiological features of a series of 27 MCPH15 cases, including eight new individuals from seven unrelated families. Genetic investigation was performed through exome sequencing (ES). Structural insights on the human Mfsd2a model and in-vitro biochemical assays were used to investigate the functional impact of the identified variants. All patients had primary microcephaly and severe developmental delay. Brain MRI showed variable degrees of white matter reduction, ventricular enlargement, callosal hypodysgenesis, and pontine and vermian hypoplasia. ES led to the identification of six novel biallelic MFSD2A variants (NG_053084.1, NM_032793.5: c.556+1G>A, c.748G>T; p.(Val250Phe), c.750_753del; p.(Cys251SerfsTer3), c.977G>A; p.(Arg326His), c.1386_1435del; p.(Gln462HisfsTer17), and c.1478C>T; p.(Pro493Leu)) and two recurrent variants (NM_032793.5: c.593C>T; p.(Thr198Met) and c.476C>T; p.(Thr159Met)). All these variants and the previously reported NM_032793.5: c.490C>A; p.(Pro164Thr) resulted in either reduced MFSD2A expression and/or transport activity. Our study further delineates the phenotypic spectrum of MCPH15, refining its clinical and neuroradiological characterization and supporting that MFSD2A deficiency causes early prenatal brain developmental disruption. We also show that poor MFSD2A expression despite normal transporter activity is a relevant pathomechanism in MCPH15.
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http://dx.doi.org/10.1038/s41431-020-0669-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7576150PMC
November 2020
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