Publications by authors named "Andrea Accogli"

68 Publications

PCDH12 variants are associated with basal ganglia anomalies and exudative vitreoretinopathy.

Eur J Med Genet 2022 Feb 17;65(2):104405. Epub 2021 Dec 17.

Department of Human Genetics, McGill University Health Centre, Montreal, Quebec, Canada; Department of Medical Imaging, Montreal Children's Hospital, McGill University Health Centre, Montreal, QC, Canada; McGill University Health Center (MUHC) Research Institute, QC, H4A 3J1, Montreal, Canada.

PCDH12 is a member of the non-clustered protocadherins that mediate cell-cell adhesion, playing crucial roles in many biological processes. Among these, PCDH12 promotes cell-cell interactions at inter-endothelial junctions, exerting essential functions in vascular homeostasis and angiogenesis. However, its exact role in eye vascular and brain development is not completely understood. To date, biallelic loss of function variants in PCDH12 have been associated with a neurodevelopmental disorder characterized by the typical neuroradiological findings of diencephalic-mesencephalic junction dysplasia and intracranial calcifications, whereas heterozygous variants have been recently linked to isolated brain calcifications in absence of cognitive impairment or other brain malformations. Recently, the phenotypic spectrum associated with PCDH12 deficiency has been expanded including cerebellar and eye abnormalities. Here, we report two female siblings harboring a novel frameshift homozygous variant (c.2169delT, p.(Val724TyrfsTer8)) in PCDH12. In addition to the typical diencephalic-mesencephalic junction dysplasia, brain MRI showed dysmorphic basal ganglia and thalamus that were reminiscent of a tubulin-like phenotype, mild cerebellar vermis hypoplasia and extensive prominence of perivascular spaces in both siblings. The oldest sister developed profound and progressive monocular visual loss and the eye exam revealed exudative vitreoretinopathy. Similar but milder eye changes were also noted in her younger sister. In summary, our report expands the clinical (brain and ocular) spectrum of PCDH12-related disorders and adds a further line of evidence underscoring the important role of PCDH12 in retinal vascular and brain development.
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http://dx.doi.org/10.1016/j.ejmg.2021.104405DOI Listing
February 2022

Pathogenic variants in RNPC3 are associated with hypopituitarism and primary ovarian insufficiency.

Genet Med 2022 Feb 30;24(2):384-397. Epub 2021 Nov 30.

Genetics and Genomic Medicine Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, University College London, London, United Kingdom; South Australian Health and Medical Research Institute (SAHMRI), The University of Adelaide, Adelaide, South Australia, Australia; Department of Paediatric Endocrinology, Great Ormond Street Hospital for Children, London, United Kingdom. Electronic address:

Purpose: We aimed to investigate the molecular basis underlying a novel phenotype including hypopituitarism associated with primary ovarian insufficiency.

Methods: We used next-generation sequencing to identify variants in all pedigrees. Expression of Rnpc3/RNPC3 was analyzed by in situ hybridization on murine/human embryonic sections. CRISPR/Cas9 was used to generate mice carrying the p.Leu483Phe pathogenic variant in the conserved murine Rnpc3 RRM2 domain.

Results: We described 15 patients from 9 pedigrees with biallelic pathogenic variants in RNPC3, encoding a specific protein component of the minor spliceosome, which is associated with a hypopituitary phenotype, including severe growth hormone (GH) deficiency, hypoprolactinemia, variable thyrotropin (also known as thyroid-stimulating hormone) deficiency, and anterior pituitary hypoplasia. Primary ovarian insufficiency was diagnosed in 8 of 9 affected females, whereas males had normal gonadal function. In addition, 2 affected males displayed normal growth when off GH treatment despite severe biochemical GH deficiency. In both mouse and human embryos, Rnpc3/RNPC3 was expressed in the developing forebrain, including the hypothalamus and Rathke's pouch. Female Rnpc3 mutant mice displayed a reduction in pituitary GH content but with no reproductive impairment in young mice. Male mice exhibited no obvious phenotype.

Conclusion: Our findings suggest novel insights into the role of RNPC3 in female-specific gonadal function and emphasize a critical role for the minor spliceosome in pituitary and ovarian development and function.
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http://dx.doi.org/10.1016/j.gim.2021.09.019DOI Listing
February 2022

An eleven-year history of Vanishing White Matter Disease in an adult patient with no cognitive decline and mutations. A case report.

Neurocase 2021 Dec 9;27(6):452-456. Epub 2021 Nov 9.

Dinogmi Department, University of Genoa, Genoa, Italy.

Vanishing White Matter Disease (VWMD) is a rare autosomal recessive leukoencephalopathy . The classical presentation is characterized by a severe cerebellar ataxia, spasticity, neurological deterioration with a chronic progressive course and episodes of acute neurological deterioration after stress conditions.We report a 52-year-old man with VWMD and atypical features who manifested two major events of transient aphasia eleven years apart with complete recovery in 48 hours. No cognitive decline was present. Brain MRI revealed typical aspects of VWMD including diffuse leukoencephalopathy with relative sparing of U-fibers. We identified the presence of c.592G>A (p.Glu198Lys) and c.1360 C>T (p.Pro454Ser) mutations in .
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http://dx.doi.org/10.1080/13554794.2021.1999984DOI Listing
December 2021

Prominent and Regressive Brain Developmental Disorders Associated with Nance-Horan Syndrome.

Brain Sci 2021 Aug 29;11(9). Epub 2021 Aug 29.

Unit of Pediatric Nephrology and Dialysis, Department of Human Pathology in Adult and Developmental Age "Gaetano Barresi, University of Messina, Via Consolare Valeria 1, 98125 Messina, Italy.

Nance-Horan syndrome (NHS) is a rare X-linked developmental disorder caused mainly by loss of function variants in the gene. NHS is characterized by congenital cataracts, dental anomalies, and distinctive facial features, and a proportion of the affected individuals also present intellectual disability and congenital cardiopathies. Despite identification of at least 40 distinct hemizygous variants leading to NHS, genotype-phenotype correlations remain largely elusive. In this study, we describe a Sicilian family affected with congenital cataracts and dental anomalies and diagnosed with NHS by whole-exome sequencing (WES). The affected boy from this family presented a late regression of cognitive, motor, language, and adaptive skills, as well as broad behavioral anomalies. Furthermore, brain imaging showed corpus callosum anomalies and periventricular leukoencephalopathy. We expand the phenotypic and mutational NHS spectrum and review potential disease mechanisms underlying the central neurological anomalies and the potential neurodevelopmental features associated with NHS.
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http://dx.doi.org/10.3390/brainsci11091150DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8465299PMC
August 2021

L1CAM variants cause two distinct imaging phenotypes on fetal MRI.

Ann Clin Transl Neurol 2021 10 12;8(10):2004-2012. Epub 2021 Sep 12.

Neuroradiology Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.

Data on fetal MRI in L1 syndrome are scarce with relevant implications for parental counseling and surgical planning. We identified two fetal MR imaging patterns in 10 fetuses harboring L1CAM mutations: the first, observed in 9 fetuses was characterized by callosal anomalies, diencephalosynapsis, and a distinct brainstem malformation with diencephalic-mesencephalic junction dysplasia and brainstem kinking. Cerebellar vermis hypoplasia, aqueductal stenosis, obstructive hydrocephalus, and pontine hypoplasia were variably associated. The second pattern observed in one fetus was characterized by callosal dysgenesis, reduced white matter, and pontine hypoplasia. The identification of these features should alert clinicians to offer a prenatal L1CAM testing.
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http://dx.doi.org/10.1002/acn3.51448DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8528460PMC
October 2021

Biallelic PI4KA variants cause neurological, intestinal and immunological disease.

Brain 2021 Dec;144(12):3597-3610

Department of Pediatrics, Sana Kliniken Duisburg, Germany.

Phosphatidylinositol 4-kinase IIIα (PI4KIIIα/PI4KA/OMIM:600286) is a lipid kinase generating phosphatidylinositol 4-phosphate (PI4P), a membrane phospholipid with critical roles in the physiology of multiple cell types. PI4KIIIα's role in PI4P generation requires its assembly into a heterotetrameric complex with EFR3, TTC7 and FAM126. Sequence alterations in two of these molecular partners, TTC7 (encoded by TTC7A or TCC7B) and FAM126, have been associated with a heterogeneous group of either neurological (FAM126A) or intestinal and immunological (TTC7A) conditions. Here we show that biallelic PI4KA sequence alterations in humans are associated with neurological disease, in particular hypomyelinating leukodystrophy. In addition, affected individuals may present with inflammatory bowel disease, multiple intestinal atresia and combined immunodeficiency. Our cellular, biochemical and structural modelling studies indicate that PI4KA-associated phenotypical outcomes probably stem from impairment of PI4KIIIα-TTC7-FAM126's organ-specific functions, due to defective catalytic activity or altered intra-complex functional interactions. Together, these data define PI4KA gene alteration as a cause of a variable phenotypical spectrum and provide fundamental new insight into the combinatorial biology of the PI4KIIIα-FAM126-TTC7-EFR3 molecular complex.
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http://dx.doi.org/10.1093/brain/awab313DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8719846PMC
December 2021

De novo DHDDS variants cause a neurodevelopmental and neurodegenerative disorder with myoclonus.

Brain 2021 Aug 11. Epub 2021 Aug 11.

Undiagnosed Diseases Program, National Institutes of Health, Bethesda, MD 20892-2152, USA.

Subcellular membrane systems are highly enriched in dolichol, whose role in organelle homeostasis and endosomal-lysosomal pathway remains largely unclear besides being involved in protein glycosylation. DHDDS encodes for the catalytic subunit (DHDDS) of the enzyme cis-prenyltransferase (cis-PTase), involved in dolichol biosynthesis and dolichol-dependent protein glycosylation in the endoplasmic reticulum. An autosomal recessive form of retinitis pigmentosa (retinitis pigmentosa 59) has been associated with a recurrent DHDDS variant. Moreover, two recurring de novo substitutions were detected in a few cases presenting with neurodevelopmental disorder, epilepsy, and movement disorder. We evaluated a large cohort of patients (n=25) with de novo pathogenic variants in DHDDS and provided the first systematic description of the clinical features and long-term outcome of this new neurodevelopmental and neurodegenerative disorder. The functional impact of the identified variants was explored by yeast complementation system and enzymatic assay. Patients presented during infancy or childhood with a variable association of neurodevelopmental disorder, generalized epilepsy, action myoclonus/cortical tremor, and ataxia. Later in the disease course they experienced a slow neurological decline with the emergence of hyperkinetic and/or hypokinetic movement disorder, cognitive deterioration, and psychiatric disturbances. Storage of lipidic material and altered lysosomes were detected in myelinated fibers and fibroblasts, suggesting a dysfunction of the lysosomal enzymatic scavenger machinery. Serum glycoprotein hypoglycosylation was not detected and, in contrast to retinitis pigmentosa and other congenital disorders of glycosylation involving dolichol metabolism, the urinary dolichol D18/D19 ratio was normal. Mapping the disease-causing variants into the protein structure revealed that most of them clustered around the active site of the DHDDS subunit. Functional studies using yeast complementation assay and in vitro activity measurements confirmed that these changes affected the catalytic activity of the cis-PTase and showed growth defect in yeast complementation system as compared with the wild-type enzyme and retinitis pigmentosa-associated protein. In conclusion, we characterized a distinctive neurodegenerative disorder due to de novo DHDDS variants, which clinically belongs to the spectrum of genetic progressive encephalopathies with myoclonus. Clinical and biochemical data from this cohort depicted a condition at the intersection of congenital disorders of glycosylation and inherited storage diseases with several features akin to of progressive myoclonus epilepsy such as neuronal ceroid lipofuscinosis and other lysosomal disorders.
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http://dx.doi.org/10.1093/brain/awab299DOI Listing
August 2021

Exome survey of individuals affected by VATER/VACTERL with renal phenotypes identifies phenocopies and novel candidate genes.

Am J Med Genet A 2021 12 2;185(12):3784-3792. Epub 2021 Aug 2.

Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

The acronym VATER/VACTERL refers to the rare nonrandom association of the following component features (CFs): vertebral defects (V), anorectal malformations (ARM) (A), cardiac anomalies (C), tracheoesophageal fistula with or without esophageal atresia (TE), renal malformations (R), and limb anomalies (L). For the clinical diagnosis, the presence of at least three CFs is required, individuals presenting with only two CFs have been categorized as VATER/VACTERL-like. The majority of VATER/VACTERL individuals displays a renal phenotype. Hitherto, variants in FGF8, FOXF1, HOXD13, LPP, TRAP1, PTEN, and ZIC3 have been associated with the VATER/VACTERL association; however, large-scale re-sequencing could only confirm TRAP1 and ZIC3 as VATER/VACTERL disease genes, both associated with a renal phenotype. In this study, we performed exome sequencing in 21 individuals and their families with a renal VATER/VACTERL or VATER/VACTERL-like phenotype to identify potentially novel genetic causes. Exome analysis identified biallelic and X-chromosomal hemizygous potentially pathogenic variants in six individuals (29%) in B9D1, FREM1, ZNF157, SP8, ACOT9, and TTLL11, respectively. The online tool GeneMatcher revealed another individual with a variant in ZNF157. Our study suggests six biallelic and X-chromosomal hemizygous VATER/VACTERL disease genes implicating all six genes in the expression of human renal malformations.
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http://dx.doi.org/10.1002/ajmg.a.62447DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8595524PMC
December 2021

ZTTK syndrome: Clinical and molecular findings of 15 cases and a review of the literature.

Am J Med Genet A 2021 12 31;185(12):3740-3753. Epub 2021 Jul 31.

St. George's Genomics Service, St. George's University Hospitals NHS FT, London, UK.

Zhu-Tokita-Takenouchi-Kim (ZTTK) syndrome is caused by de novo loss-of-function variants in the SON gene (MIM #617140). This multisystemic disorder is characterized by intellectual disability, seizures, abnormal brain imaging, variable dysmorphic features, and various congenital anomalies. The wide application and increasing accessibility of whole exome sequencing (WES) has helped to identify new cases of ZTTK syndrome over the last few years. To date, there have been approximately 45 cases reported in the literature. Here, we describe 15 additional individuals with variants in the SON gene, including those with missense variants bringing the total number of known cases to 60. We have reviewed the clinical and molecular data of these new cases and all previously reported cases to further delineate the most common as well as emerging clinical findings related to this syndrome. Furthermore, we aim to delineate any genotype-phenotype correlations specifically for a recurring pathogenic four base pair deletion (c.5753_5756del) along with discussing the impact of missense variants seen in the SON gene.
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http://dx.doi.org/10.1002/ajmg.a.62445DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8595531PMC
December 2021

Epileptic encephalopathy caused by ARV1 deficiency: Refinement of the genotype-phenotype spectrum and functional impact on GPI-anchored proteins.

Clin Genet 2021 11 29;100(5):607-614. Epub 2021 Jul 29.

CHU Sainte-Justine Research Center, University of Montreal, Montreal, Quebec, Canada.

Early infantile epileptic encephalopathy 38 (EIEE38, MIM #617020) is caused by biallelic variants in ARV1, encoding a transmembrane protein of the endoplasmic reticulum with a pivotal role in glycosylphosphatidylinositol (GPI) biosynthesis. We ascertained seven new patients from six unrelated families harboring biallelic variants in ARV1, including five novel variants. Affected individuals showed psychomotor delay, hypotonia, early onset refractory seizures followed by regression and specific neuroimaging features. Flow cytometric analysis on patient fibroblasts showed a decrease in GPI-anchored proteins on the cell surface, supporting a lower residual activity of the mutant ARV1 as compared to the wildtype. A rescue assay through the transduction of lentivirus expressing wild type ARV1 cDNA effectively rescued these alterations. This study expands the clinical and molecular spectrum of the ARV1-related encephalopathy, confirming the essential role of ARV1 in GPI biosynthesis and brain function.
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http://dx.doi.org/10.1111/cge.14033DOI Listing
November 2021

Pathogenic variants in PIDD1 lead to an autosomal recessive neurodevelopmental disorder with pachygyria and psychiatric features.

Eur J Hum Genet 2021 08 24;29(8):1226-1234. Epub 2021 Jun 24.

Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, Queen Square, WC1N3BG London, London, UK.

The PIDDosome is a multiprotein complex, composed by the p53-induced death domain protein 1 (PIDD1), the bipartite linker protein CRADD (also known as RAIDD) and the proform of caspase-2 that induces apoptosis in response to DNA damage. In the recent years, biallelic pathogenic variants in CRADD have been associated with a neurodevelopmental disorder (MRT34; MIM 614499) characterized by pachygyria with a predominant anterior gradient, megalencephaly, epilepsy and intellectual disability. More recently, biallelic pathogenic variants in PIDD1 have been described in a few families with apparently nonsydnromic intellectual disability. Here, we aim to delineate the genetic and radio-clinical features of PIDD1-related disorder. Exome sequencing was carried out in six consanguineous families. Thorough clinical and neuroradiological evaluation was performed for all the affected individuals as well as reviewing all the data from previously reported cases. We identified five distinct novel homozygous variants (c.2584C>T p.(Arg862Trp), c.1340G>A p.(Trp447*), c.2116_2120del p.(Val706Hisfs*30), c.1564_1565delCA p.(Gln522fs*44), and c.1804_1805del p.(Gly602fs*26) in eleven subjects displaying intellectual disability, behaviorial and psychiatric features, and a typical anterior-predominant pachygyria, remarkably resembling the CRADD-related neuroimaging pattern. In summary, we outlin`e the phenotypic and molecular spectrum of PIDD1 biallelic variants supporting the evidence that the PIDD1/CRADD/caspase-2 signaling is crucial for normal gyration of the developing human neocortex as well as cognition and behavior.
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http://dx.doi.org/10.1038/s41431-021-00910-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8385073PMC
August 2021

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

Seizure 2021 10 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
October 2021

Clinical and Genetic Features in Patients With Reflex Bathing Epilepsy.

Neurology 2021 08 2;97(6):e577-e586. Epub 2021 Jun 2.

From IRCCS Istituto Giannina Gaslini (A.A., M.S., M.I., A.R., B.C., P.S., S.B., V.D.S., C.M., F.Z., P.S.); Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI) (A.A., M.S., P.S., V.D.S., C.M., F.Z., P.S.), University of Genoa, Italy; Neuropediatrics Section of the Department of Pediatrics (G.W.), Asklepios Clinic Hamburg Nord-Heidberg, Hamburg; Department of Pediatric and Adolescent Medicine II (Neuropediatrics, Social Pediatrics) (G.W.), University Medical Centre Schleswig-Holstein, Kiel, Germany; Department of Neurosciences (C.C., C.D.L.), Pediatric Neurology Unit, Tor Vergata University, Roma; Human Genetics (L.C., F. Brancati), Department of Life, Health, and Environmental Sciences, and Department of Pediatrics (A.V.), University of L'Aquila; Child Neuropsychiatry Unit (V.B.), Department of Mental Health, ASST-LARIANA, Como; Medical Genetics Unit (P.P.), "S. Maria della Misericordia" Hospital, Perugia, Italy; Department of Pediatric Neurology (A.F.-J.), Hospital Universitario Quirónsalud and Universidad Europea de Madrid, Madrid, Spain; Istanbul University Istanbul Faculty of Medicine (N.B.), Department of Neurology, Turkey; Department of Biomedicine and Prevention (G.N.), Tor Vergata University of Rome; IRCCS Neuromed (G.N.), Pozzilli, Italy; Department of Pharmacology (G.N.), School of Medicine, University of Nevada, Reno; Department of Pediatrics (C.v.S.), University Hospital Munich, Germany; Paracelsus Medical University (C.v.S.), Salzburg, Austria; Epilepsy Center for Children and Adolescents (F.K., G.J.K.), Vogtareuth, Germany; Department of Neuropediatrics (G.C.W., G.R.), University Children's Hospital Zurich, Switzerland; Translational and Clinical Research Institute (D.L.-S., R.H.T., M.L.), Newcastle University; Department of Clinical Neurosciences (D.L.-S., R.H.T., M.L.), Newcastle Upon Tyne Hospitals National Health Service Foundation Trust, UK; Epilepsy Center (S.S.), Federico II University, Napoli, Italy; Institute of Human Genetics (C.D.), University Hospital Essen, University of Duisburg-Essen, Essen, Germany; Institut du Cerveau et de la Moelle épinière (ICM) (C.D.), Sorbonne Université, UMR S 1127, Inserm U1127, CNRS UMR 7225, Paris, France; Center for Synaptic Neuroscience and Technology (F.Benfenati), Istituto Italiano di Tecnologia; IRCCS Ospedale Policlinico San Martino (F. Benfenati), Genoa; and Human Functional Genomics (F. Brancati), IRCCS San Raffaele Pisana, Rome, Italy.

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

Methods: We investigated by Sanger and targeted resequencing the gene in 12 individuals from 10 different families presenting with seizures triggered primarily by bathing or showering. An additional 12 individuals 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 , 9 of which are novel. Conversely, none of the individuals with hot-water epilepsy displayed variants. In mutated individuals, seizures were typically triggered by showering or bathing regardless of the water temperature. Additional triggers included fingernail clipping, haircutting, or watching someone take a shower. Unprovoked seizures and a variable degree of developmental delay were also common.

Conclusion: Bathing epilepsy is genetically distinct reflex epilepsy caused mainly by mutations.
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http://dx.doi.org/10.1212/WNL.0000000000012298DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8424500PMC
August 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

A rare triad of morning glory disc anomaly, moyamoya vasculopathy, and transsphenoidal cephalocele: pathophysiological considerations and surgical management.

Neurol Sci 2021 Dec 6;42(12):5433-5439. Epub 2021 Apr 6.

Department of Neurosurgery, IRCCS Istituto Giannina Gaslini Children's Hospital, Genoa, Italy.

Morning glory disc anomaly is a congenital abnormality of the optic disc and peripapillary retina reported as an isolated condition or associated with various anomalies, including basal encephaloceles and moyamoya vasculopathy. However, the co-occurrence of these three entities is extremely rare and the pathogenesis is still poorly understood. Moreover, data on the surgical management and long-term follow-up of the intracranial anomalies are scarce. Here, we describe the case of a 11-year-old boy with morning glory disc anomaly, transsphenoidal cephalocele, and moyamoya vasculopathy, who underwent bilateral indirect revascularization with encephalo-duro-myo-arterio-pericranio-synangiosis at the age of 2 years, and endoscopic repair of the transsphenoidal cephalocele at the age of 6 years. A rare missense variant (c.1081T>C,p.Tyr361His) was found in OFD1, a gene responsible for a X-linked ciliopathy, the oral-facial-digital syndrome type 1 (OFD1; OMIM 311200). This case expands the complex phenotype of OFD1 syndrome and suggests a possible involvement of OFD1 gene and Shh pathway in the pathogenesis of these anomalies.
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http://dx.doi.org/10.1007/s10072-021-05221-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8642253PMC
December 2021

Diagnostic Approach to Cerebellar Hypoplasia.

Cerebellum 2021 Aug 3;20(4):631-658. Epub 2021 Feb 3.

Department of Pediatrics, Division of Pediatric Neurology, McGill University, Montreal, Canada.

Cerebellar hypoplasia (CH) refers to a cerebellum of reduced volume with preserved shape. CH is associated with a broad heterogeneity in neuroradiologic features, etiologies, clinical characteristics, and neurodevelopmental outcomes, challenging physicians evaluating children with CH. Traditionally, neuroimaging has been a key tool to categorize CH based on the pattern of cerebellar involvement (e.g., hypoplasia of cerebellar vermis only vs. hypoplasia of both the vermis and cerebellar hemispheres) and the presence of associated brainstem and cerebral anomalies. With the advances in genetic technologies of the recent decade, many novel CH genes have been identified, and consequently, a constant updating of the literature and revision of the classification of cerebellar malformations are needed. Here, we review the current literature on CH. We propose a systematic approach to recognize specific neuroimaging patterns associated with CH, based on whether the CH is isolated or associated with posterior cerebrospinal fluid anomalies, specific brainstem or cerebellar malformations, brainstem hypoplasia with or without cortical migration anomalies, or dysplasia. The CH radiologic pattern and clinical assessment will allow the clinician to guide his investigations and genetic testing, give a more precise diagnosis, screen for associated comorbidities, and improve prognostication of associated neurodevelopmental outcomes.
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http://dx.doi.org/10.1007/s12311-020-01224-5DOI Listing
August 2021

Variants in GNAI1 cause a syndrome associated with variable features including developmental delay, seizures, and hypotonia.

Genet Med 2021 05 20;23(5):881-887. Epub 2021 Jan 20.

Duke University Health System, Durham, NC, USA.

Purpose: Neurodevelopmental disorders (NDDs) encompass a spectrum of genetically heterogeneous disorders with features that commonly include developmental delay, intellectual disability, and autism spectrum disorders. We sought to delineate the molecular and phenotypic spectrum of a novel neurodevelopmental disorder caused by variants in the GNAI1 gene.

Methods: Through large cohort trio-based exome sequencing and international data-sharing, we identified 24 unrelated individuals with NDD phenotypes and a variant in GNAI1, which encodes the inhibitory Gαi1 subunit of heterotrimeric G-proteins. We collected detailed genotype and phenotype information for each affected individual.

Results: We identified 16 unique variants in GNAI1 in 24 affected individuals; 23 occurred de novo and 1 was inherited from a mosaic parent. Most affected individuals have a severe neurodevelopmental disorder. Core features include global developmental delay, intellectual disability, hypotonia, and epilepsy.

Conclusion: This collaboration establishes GNAI1 variants as a cause of NDDs. GNAI1-related NDD is most often characterized by severe to profound delays, hypotonia, epilepsy that ranges from self-limiting to intractable, behavior problems, and variable mild dysmorphic features.
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http://dx.doi.org/10.1038/s41436-020-01076-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8107131PMC
May 2021

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

Neurogenesis, neuronal migration, and axon guidance.

Handb Clin Neurol 2020 ;173:25-42

Research Institute, McGill University Health Centre, Montreal, QC, Canada; Department of Pediatrics, Division of Pediatric Neurology, McGill University, Montreal, QC, Canada. Electronic address:

Development of the central nervous system (CNS) is a complex, dynamic process that involves a precisely orchestrated sequence of genetic, environmental, biochemical, and physical factors from early embryonic stages to postnatal life. Duringthe past decade, great strides have been made to unravel mechanisms underlying human CNS development through the employment of modern genetic techniques and experimental approaches. In this chapter, we review the current knowledge regarding the main developmental processes and signaling mechanisms of (i) neurogenesis, (ii) neuronal migration, and (iii) axon guidance. We discuss mechanisms related to neural stem cells proliferation, migration, terminal translocation of neuronal progenitors, and axon guidance and pathfinding. For each section, we also provide a comprehensive overview of the underlying regulatory processes, including transcriptional, posttranscriptional, and epigenetic factors, and a myriad of signaling pathways that are pivotal to determine the fate of neuronal progenitors and newly formed migrating neurons. We further highlight how impairment of this complex regulating system, such as mutations in its core components, may cause cortical malformation, epilepsy, intellectual disability, and autism in humans. A thorough understanding of normal human CNS development is thus crucial to decipher mechanisms responsible for neurodevelopmental disorders and in turn guide the development of effective and targeted therapeutic strategies.
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http://dx.doi.org/10.1016/B978-0-444-64150-2.00004-6DOI Listing
July 2021

Aicardi Syndrome: Key Fetal MRI Features and Prenatal Differential Diagnosis.

Neuropediatrics 2020 08 3;51(4):276-285. Epub 2020 Jul 3.

Department of Pediatric Radiology and Neuroradiology, Children's Hospital V. Buzzi, Milan, Italy.

Objective: This study was aimed to investigate the prenatal findings in Aicardi syndrome (AIC) by intrauterine magnetic resonance imaging (iuMRI) suggesting possible diagnostic criteria and differential diagnosis.

Methods: The iuMRI features of nine AIC confirmed cases were described and then compared with those of postnatal MRI. Furthermore, all iuMRI cases with both corpus callosum (CC) agenesis-dysgenesis and cortical malformation (AIC mimickers) were retrospectively reviewed and compared with iuMRI AIC cases, in order to identify possible neuroradiological predictors of AIC syndrome. For this purpose, Chi-square statistic and binary logistic regression analysis were performed.

Results: In all AIC cases, iuMRI was able to detect CC agenesis-dysgenesis and cortical development anomalies. Postnatal MRI revealed some additional findings mainly including further cystic lesions and in two cases small coloboma. A statistically significant difference between AIC and AIC mimicker were found regarding sex, nodular heterotopias, posterior fossa abnormalities, coloboma, and cortical gyration abnormalities. The most predictive variables in the logistic regression model were cortical gyration abnormalities, coloboma, and sex.

Conclusion: The iuMRI findings may suggest prenatal diagnosis of AIC syndrome with significant impact on parental counseling. Among possible differential diagnoses, tubulinopathies emerged.
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http://dx.doi.org/10.1055/s-0040-1710528DOI Listing
August 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

Targeted re-sequencing in malformations of cortical development: genotype-phenotype correlations.

Seizure 2020 Aug 3;80:145-152. Epub 2020 Jun 3.

Unit of Child Neuropsychiatry, ARNAS Civico G. Di Cristina Benefratelli, Palermo, Italy.

Purpose: Malformations of cortical development (MCD) are a phenotypically and genetically heterogeneous group of disorders, for which the diagnostic rate of genetic testing in a clinical setting remains to be clarified. In this study we aimed to assess the diagnostic rate of germline and pathogenic variants using a custom panel in a heterogeneous group of subjects with MCD and explore genotype-phenotype correlations.

Methods: A total of 84 subjects with different MCD were enrolled. Genomic DNA was isolated from peripheral blood. Fifty-nine tartget genes were assessed using a custom next-generation sequencing (NGS) panel.

Results: Genetic causes were identified in one-fourth of our cohort (21.4 %). Overall, we identified 19 pathogenic or likely pathogenic single-nucleotide variants in 11 genes among 18 subjects, including PAFAH1B1 (LIS1) (n = 3), TUBA1A (n = 3), DYNC1H1 (n = 3), ACTG1 (n = 2), TUBB2B (n = 1), TUBB3 (n = 1), DCX (n = 1), FLNA (n = 1), LAMA2 (n = 1), POMGNT2 (n = 1) and VLDLR (n = 1). The diagnostic yield was higher in patients with lissencephaly/pachygyria (60 %) (p = 0.001), cobblestone malformation (50 %), and subcortical band heterotopia (SBH) (40 %). Furthermore, five out of six subjects with suspect tubulinopathies on imaging harboured pathogenic variants in tubulin genes. Overall, germline pathogenic variants were more likely to be identified if MCD were diffuse (p = 0.002) and associated with other central nervous system malformations (p = 0.029). Moderate to severe intellectual disability was also more commonly associated with pathogenic variants (p = 0.044).

Conclusion: Customized gene panels may support the diagnostic work-up for some specific MCD, especially when these are diffuse, bilateral and associated with other brain malformations.
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http://dx.doi.org/10.1016/j.seizure.2020.05.023DOI Listing
August 2020

Psychiatric features and variable neurodevelopment outcome in four females with IQSEC2 spectrum disorder.

J Genet 2020 ;99

Department of Medical Genetics, McGill University Health Centre, Montreal, QC, Canada.

is an X-linked gene highly expressed at the excitatory synapses where it plays a crucial role in α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor trafficking and synaptic plasticity. To date, several males and females with severe to profound intellectual disability have been reported harbouring frameshift and nonsense variants in this gene, whereas a milder phenotype has been recognized in females carrying missense pathogenic variants. Here, we report two novel variants in four females with psychiatric features and otherwise variable cognitive impairment. A female (case 1) with severe verbal language learning disorder and a psychotic episode (precipitated by exposure to anti-contraceptive pill) harboured a pathogenic frameshift variant (c.1170dupG,p.Gln391Alafs*5), whereas the female proband of family 2, displaying severe psychomotor regression and complex psychiatric features carried a missense variant of uncertain significance (c.770G[A,p.Ser257Asn) that was maternally inherited. Skewed X-inactivation was noted in the carrier mother. The maternal aunt, affected by schizophrenia, was found to bear the same variant. We discuss the variable clinical presentation of IQSEC2 spectrum disorders and the challenging genotype-phenotype correlation, including the possible role of environmental factors as triggers for decompensation. Our report highlights how psychiatric features may be the main clinical presentation in subtle IQSEC2 phenotype, suggesting that the prevalence of IQSEC2 mutations in patients with psychiatric disorders may be underestimated.
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October 2020

Sinus pericranii, skull defects, and structural brain anomalies in TRAF7-related disorder.

Birth Defects Res 2020 08 27;112(14):1085-1092. Epub 2020 May 27.

UOC Neurosurgery, IRCCS Istituto Giannina Gaslini, Genoa, Italy.

Background: Several somatic mutations in TRAF7 have been reported in cancers, whereas a few germline heterozygous mutations have been recently linked to a neurodevelopmental disorder, characterized by craniofacial dysmorphisms, congenital heart defects, and digital anomalies.

Cases: We report two subjects harboring de novo heterozygous missense variants in TRAF7, namely the recurrent 1964G>A(p.Arg655Gln) and the novel missense c.1204C>G(p.Leu402Val) variants. In addition to the typical hallmarks of the TRAF7-related disorder, both subjects presented with a recognizable "pear-shaped" skull due to multiple craniosynostosis, sinus pericranii, skull base/cranio-cervical junction anomalies, dysgyria, and inferior cerebellar vermis hypoplasia.

Conclusions: Hence, we expand the genotypic and phenotypic spectrum of this neurodevelopmental disorder, discussing possible implications for clinical management of subjects with germline TRAF7 mutations.
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http://dx.doi.org/10.1002/bdr2.1711DOI Listing
August 2020

Congenital posterior cervical spine malformation due to biallelic c.240-4T>G RIPPLY2 variant: A discrete entity.

Am J Med Genet A 2020 06 25;182(6):1466-1472. Epub 2020 Mar 25.

Centre de génétique humaine, Université de Franche Comté, Besançon, France.

The clinical and radiological spectrum of spondylocostal dysostosis syndromes encompasses distinctive costo-vertebral anomalies. RIPPLY2 biallelic pathogenic variants were described in two distinct cervical spine malformation syndromes: Klippel-Feil syndrome and posterior cervical spine malformation. RIPPLY2 is involved in the determination of rostro-caudal polarity and somite patterning during development. To date, only four cases have been reported. The current report aims at further delineating the posterior malformation in three new patients. Three patients from two unrelated families underwent clinical and radiological examination through X-ray, 3D computed tomography and brain magnetic resonance imaging. After informed consent was obtained, family-based whole exome sequencing (WES) was performed. Complex vertebral segmentation defects in the cervico-thoracic spine were observed in all patients. WES led to the identification of the homozygous splicing variant c.240-4T>G in all subjects. This variant is predicted to result in aberrant splicing of Exon 4. The current report highlights a subtype of cervical spine malformation with major atlo-axoidal malformation compromising spinal cord integrity. This distinctive mutation-specific pattern of malformation differs from Klippel-Feil syndrome and broadens the current classification, defining a sub-type of RIPPLY2-related skeletal disorder. Of note, the phenotype of one patient overlaps with oculo-auriculo-vertebral spectrum disorder.
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http://dx.doi.org/10.1002/ajmg.a.61549DOI Listing
June 2020

Damaging de novo missense variants in EEF1A2 lead to a developmental and degenerative epileptic-dyskinetic encephalopathy.

Hum Mutat 2020 07 6;41(7):1263-1279. Epub 2020 Apr 6.

Department of Genetics, Utrecht University, Utrecht, The Netherlands.

Heterozygous de novo variants in the eukaryotic elongation factor EEF1A2 have previously been described in association with intellectual disability and epilepsy but never functionally validated. Here we report 14 new individuals with heterozygous EEF1A2 variants. We functionally validate multiple variants as protein-damaging using heterologous expression and complementation analysis. Our findings allow us to confirm multiple variants as pathogenic and broaden the phenotypic spectrum to include dystonia/choreoathetosis, and in some cases a degenerative course with cerebral and cerebellar atrophy. Pathogenic variants appear to act via a haploinsufficiency mechanism, disrupting both the protein synthesis and integrated stress response functions of EEF1A2. Our studies provide evidence that EEF1A2 is highly intolerant to variation and that de novo pathogenic variants lead to an epileptic-dyskinetic encephalopathy with both neurodevelopmental and neurodegenerative features. Developmental features may be driven by impaired synaptic protein synthesis during early brain development while progressive symptoms may be linked to an impaired ability to handle cytotoxic stressors.
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http://dx.doi.org/10.1002/humu.24015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7292794PMC
July 2020

De novo heterozygous missense and loss-of-function variants in CDC42BPB are associated with a neurodevelopmental phenotype.

Am J Med Genet A 2020 05 7;182(5):962-973. Epub 2020 Feb 7.

Center for Pediatric Genomic Medicine, Children's Mercy Hospital, Kansas City, Missouri.

CDC42BPB encodes MRCKβ (myotonic dystrophy-related Cdc42-binding kinase beta), a serine/threonine protein kinase, and a downstream effector of CDC42, which has recently been associated with Takenouchi-Kosaki syndrome, an autosomal dominant neurodevelopmental disorder. We identified 12 heterozygous predicted deleterious variants in CDC42BPB (9 missense, 2 frameshift, and 1 nonsense) in 14 unrelated individuals (confirmed de novo in 11/14) with neurodevelopmental disorders including developmental delay/intellectual disability, autism, hypotonia, and structural brain abnormalities including cerebellar vermis hypoplasia and agenesis/hypoplasia of the corpus callosum. The frameshift and nonsense variants in CDC42BPB are expected to be gene-disrupting and lead to haploinsufficiency via nonsense-mediated decay. All missense variants are located in highly conserved and functionally important protein domains/regions: 3 are found in the protein kinase domain, 2 are in the citron homology domain, and 4 in a 20-amino acid sequence between 2 coiled-coil regions, 2 of which are recurrent. Future studies will help to delineate the natural history and to elucidate the underlying biological mechanisms of the missense variants leading to the neurodevelopmental and behavioral phenotypes.
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http://dx.doi.org/10.1002/ajmg.a.61505DOI Listing
May 2020

Heterozygous Missense Pathogenic Variants Within the Second Spectrin Repeat of SPTBN2 Lead to Infantile-Onset Cerebellar Ataxia.

J Child Neurol 2020 02 16;35(2):106-110. Epub 2019 Oct 16.

Department of Pediatrics, Division of Pediatric Neurology, McGill University, Montreal, Quebec, Canada.

The term encompasses a heterogeneous group of neurodegenerative disorders due to pathogenic variants in more than 100 genes, underlying 2 major groups of ataxia: autosomal dominant cerebellar ataxias (ADCA, also known as spinocerebellar ataxias [SCAs]) due to heterozygous variants or polyglutamine triplet expansions leading to adult-onset ataxia, and autosomal recessive spinocerebellar ataxias (ARCAs, also known as SCARs) due to biallelic variants, usually resulting in more severe and earlier-onset cerebellar ataxia. Certain ataxia genes, including which encodes β-III spectrin, are responsible for both SCA and SCAR, depending on whether the pathogenic variant occurs in a monoallelic or biallelic state, respectively. Accordingly, 2 major phenotypes have been linked to : pathogenic heterozygous in-frame deletions and missense variants result in an adult-onset, slowly progressive ADCA (SCA5) through a dominant negative effect, whereas biallelic loss-of-function variants cause SCAR14, an allelic disorder characterized by infantile-onset cerebellar ataxia and cognitive impairment. Of note, 2 heterozygous missense variants (c.1438C>T, p.R480 W; c.1309C>G, p.R437G), both lying in the second spectrin repeat of SPTBN2, have been linked to infantile-onset cerebellar ataxia, similar to SCAR14. Here, we report a novel heterozygous pathogenic missense variant (c.1310G>A) in in a child with infantile-onset cerebellar ataxia and mild cognitive impairment. This variant affects the same R437 residue of the second spectrin repeat but results in a different amino acid change (p.R437Q). We review previously reported cases and discuss possible pathomechanisms responsible for the early-onset cerebellar phenotype due to disease-causing variants in the second spectrin repeat.
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http://dx.doi.org/10.1177/0883073819878917DOI Listing
February 2020
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