@article {858, title = {Whole-exome sequencing in adult patients with developmental and epileptic encephalopathy: It is never too late.}, journal = {Clin Genet}, volume = {98}, year = {2020}, month = {2020 11}, pages = {477-485}, abstract = {

Developmental and epileptic encephalopathies (DEE) encompass rare, sporadic neurodevelopmental disorders and usually with pediatric onset. As these conditions are characterized by marked clinical and genetic heterogeneity, whole-exome sequencing (WES) represents the strategy of choice for the molecular diagnosis. While its usefulness is well established in pediatric DEE cohorts, our study is aimed at assessing the WES feasibility in adult DEE patients who experienced a diagnostic odyssey prior to the advent of this technique. We analyzed exomes from 71 unrelated adult DEE patients, consecutively recruited from an Italian cohort for the EPI25 Project. All patients underwent accurate clinical and electrophysiological characterization. An overwhelming percentage (90.1\%) had already undergone negative genetic testing. Variants were classified according to the American College of Medical Genetics and Genomics guidelines. WES disclosed 24 (likely) pathogenic variants among 18 patients in epilepsy-related genes with either autosomal dominant, recessive or X-linked inheritance. Ten of these were novel. We obtained a diagnostic yield of 25.3\%, higher among patients with brain malformations, early-onset epilepsy and dysmorphisms. Despite a median diagnostic delay of 38.7 years, WES analysis provided the long-awaited diagnosis for 18 adult patients, which also had an impact on the clinical management of 50\% of them.

}, issn = {1399-0004}, doi = {10.1111/cge.13823}, author = {Minardi, Raffaella and Licchetta, Laura and Baroni, Maria Chiara and Pippucci, Tommaso and Stipa, Carlotta and Mostacci, Barbara and Severi, Giulia and Toni, Francesco and Bergonzini, Luca and Carelli, Valerio and Seri, Marco and Tinuper, Paolo and Bisulli, Francesca} } @article {656, title = {Exploring by whole exome sequencing patients with initial diagnosis of Rubinstein-Taybi syndrome: the interconnections of epigenetic machinery disorders.}, journal = {Hum Genet}, volume = {138}, year = {2019}, month = {2019 Mar}, pages = {257-269}, abstract = {

Rubinstein-Taybi syndrome (RSTS) is an autosomal-dominant neurodevelopmental disease affecting 1:125,000 newborns characterized by intellectual disability, growth retardation, facial dysmorphisms and skeletal abnormalities. RSTS is caused by mutations in genes encoding for writers of the epigenetic machinery: CREBBP (~ 60\%) or its homologous EP300 (~ 10\%). No causative mutation is identified in up to 30\% of patients. We performed whole-exome sequencing (WES) on eight RSTS-like individuals who had normal high-resolution array CGH testing and were CREBBP- and EP300-mutation -negative, to identify the molecular cause. In four cases, we identified putatively causal variants in three genes (ASXL1, KMT2D and KMT2A) encoding members of the epigenetic machinery known to be associated with the Bohring-Opitz, Kabuki and Wiedemann-Steiner syndromes. Each variant is novel, de novo, fulfills the ACMG criteria and is predicted to result in loss-of-function leading to haploinsufficiency of the epi-gene. In two of the remaining cases, homozygous/compound heterozygous variants in XYLT2 and PLCB4 genes, respectively, associated with spondyloocular and auriculocondylar 2 syndromes and in the latter an additional candidate variant in XRN2, a gene yet unrelated to any disease, were detected, but their pathogenicity remains uncertain. These results underscore the broad clinical spectrum of Mendelian disorders of the epigenetic apparatus and the high rate of WES disclosure of the genetic basis in cases which may pose a challenge for phenotype encompassing distinct syndromes. The overlapping features of distinct intellectual disability syndromes reflect common pathogenic molecular mechanisms affecting the complex regulation of balance between open and closed chromatin.

}, keywords = {Child, Child, Preschool, Comparative Genomic Hybridization, CREB-Binding Protein, E1A-Associated p300 Protein, Epigenesis, Genetic, Facies, Female, Genetic Association Studies, Humans, Infant, Infant, Newborn, Male, Mutation, Phenotype, Rubinstein-Taybi Syndrome, Whole Exome Sequencing}, issn = {1432-1203}, doi = {10.1007/s00439-019-01985-y}, author = {Negri, Gloria and Magini, Pamela and Milani, Donatella and Crippa, Milena and Biamino, Elisa and Piccione, Maria and Sotgiu, Stefano and Perr{\`\i}a, Chiara and Vitiello, Giuseppina and Frontali, Marina and Boni, Antonella and Di Fede, Elisabetta and Gandini, Maria Chiara and Colombo, Elisa Adele and Bamshad, Michael J and Nickerson, Deborah A and Smith, Joshua D and Loddo, Italia and Finelli, Palma and Seri, Marco and Pippucci, Tommaso and Larizza, Lidia and Gervasini, Cristina} } @article {719, title = {Loss of SMPD4 Causes a Developmental Disorder Characterized by Microcephaly and Congenital Arthrogryposis.}, journal = {Am J Hum Genet}, volume = {105}, year = {2019}, month = {2019 Oct 03}, pages = {689-705}, abstract = {

Sphingomyelinases generate ceramide from sphingomyelin as a second messenger in intracellular signaling pathways involved in cell proliferation, differentiation, or apoptosis. Children from 12 unrelated families presented with microcephaly, simplified gyral pattern of the cortex, hypomyelination, cerebellar hypoplasia, congenital arthrogryposis, and early fetal/postnatal demise. Genomic analysis revealed bi-allelic loss-of-function variants in SMPD4, coding for the neutral sphingomyelinase-3 (nSMase-3/SMPD4). Overexpression of human Myc-tagged SMPD4 showed localization both to the outer nuclear envelope and the ER and additionally revealed interactions with several nuclear pore complex proteins by proteomics analysis. Fibroblasts from affected individuals showed ER cisternae abnormalities, suspected for increased autophagy, and were more susceptible to apoptosis under stress conditions, while treatment with siSMPD4 caused delayed cell cycle progression. Our data show that SMPD4 links homeostasis of membrane sphingolipids to cell fate by regulating the cross-talk between the ER and the outer nuclear envelope, while its loss reveals a pathogenic mechanism in microcephaly.

}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2019.08.006}, author = {Magini, Pamela and Smits, Daphne J and Vandervore, Laura and Schot, Rachel and Columbaro, Marta and Kasteleijn, Esmee and van der Ent, Mees and Palombo, Flavia and Lequin, Maarten H and Dremmen, Marjolein and de Wit, Marie Claire Y and Severino, Mariasavina and Divizia, Maria Teresa and Striano, Pasquale and Ordonez-Herrera, Natalia and Alhashem, Amal and Al Fares, Ahmed and Al Ghamdi, Malak and Rolfs, Arndt and Bauer, Peter and Demmers, Jeroen and Verheijen, Frans W and Wilke, Martina and van Slegtenhorst, Marjon and van der Spek, Peter J and Seri, Marco and Jansen, Anna C and Stottmann, Rolf W and Hufnagel, Robert B and Hopkin, Robert J and Aljeaid, Deema and Wiszniewski, Wojciech and Gawlinski, Pawel and Laure-Kamionowska, Milena and Alkuraya, Fowzan S and Akleh, Hanah and Stanley, Valentina and Musaev, Damir and Gleeson, Joseph G and Zaki, Maha S and Brunetti-Pierri, Nicola and Cappuccio, Gerarda and Davidov, Bella and Basel-Salmon, Lina and Bazak, Lily and Shahar, Noa Ruhrman and Bertoli-Avella, Aida and Mirzaa, Ghayda M and Dobyns, William B and Pippucci, Tommaso and Fornerod, Maarten and Mancini, Grazia M S} } @article {543, title = {Functional Dysregulation of CDC42 Causes Diverse Developmental Phenotypes.}, journal = {Am J Hum Genet}, volume = {102}, year = {2018}, month = {2018 Feb 01}, pages = {309-320}, abstract = {

Exome sequencing has markedly enhanced the discovery of genes implicated in Mendelian disorders, particularly for individuals in whom a known clinical entity could not be assigned. This has led to the recognition that phenotypic heterogeneity resulting from allelic mutations occurs more commonly than previously appreciated. Here, we report that missense variants in CDC42, a gene encoding a small GTPase functioning as an intracellular signaling node, underlie a clinically heterogeneous group of phenotypes characterized by variable growth dysregulation, facial dysmorphism, and neurodevelopmental, immunological, and hematological anomalies, including a phenotype resembling Noonan syndrome, a developmental disorder caused by dysregulated RAS signaling. In silico, in~vitro, and in~vivo analyses demonstrate that mutations variably perturb CDC42 function by altering the switch between the active and inactive states of the GTPase and/or affecting CDC42 interaction with effectors, and differentially disturb cellular and developmental processes. These findings reveal the remarkably variable impact that dominantly acting CDC42 mutations have on cell function and development, creating challenges in syndrome definition, and exemplify the importance of functional profiling for syndrome recognition and delineation.

}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.12.015}, author = {Martinelli, Simone and Krumbach, Oliver H F and Pantaleoni, Francesca and Coppola, Simona and Amin, Ehsan and Pannone, Luca and Nouri, Kazem and Farina, Luciapia and Dvorsky, Radovan and Lepri, Francesca and Buchholzer, Marcel and Konopatzki, Raphael and Walsh, Laurence and Payne, Katelyn and Pierpont, Mary Ella and Vergano, Samantha Schrier and Langley, Katherine G and Larsen, Douglas and Farwell, Kelly D and Tang, Sha and Mroske, Cameron and Gallotta, Ivan and Di Schiavi, Elia and Della Monica, Matteo and Lugli, Licia and Rossi, Cesare and Seri, Marco and Cocchi, Guido and Henderson, Lindsay and Baskin, Berivan and Alders, Marielle and Mendoza-Londono, Roberto and Dupuis, Lucie and Nickerson, Deborah A and Chong, Jessica X and Meeks, Naomi and Brown, Kathleen and Causey, Tahnee and Cho, Megan T and Demuth, Stephanie and Digilio, Maria Cristina and Gelb, Bruce D and Bamshad, Michael J and Zenker, Martin and Ahmadian, Mohammad Reza and Hennekam, Raoul C and Tartaglia, Marco and Mirzaa, Ghayda M} } @article {21, title = {Recurrent De Novo and Biallelic Variation of ATAD3A, Encoding a Mitochondrial Membrane Protein, Results in Distinct Neurological Syndromes.}, journal = {Am J Hum Genet}, volume = {99}, year = {2016}, month = {2016 Oct 06}, pages = {831-845}, abstract = {

ATPase family AAA-domain containing protein 3A (ATAD3A) is a nuclear-encoded mitochondrial membrane protein implicated in mitochondrial dynamics, nucleoid organization, protein translation, cell growth, and cholesterol metabolism. We identified a recurrent de novo ATAD3A c.1582C>T (p.Arg528Trp) variant by whole-exome sequencing (WES) in five unrelated individuals with a core phenotype of global developmental delay, hypotonia, optic atrophy, axonal neuropathy, and hypertrophic cardiomyopathy. We also describe two families with biallelic variants in ATAD3A, including a homozygous variant in two siblings, and biallelic ATAD3A deletions mediated by nonallelic homologous recombination (NAHR) between ATAD3A and gene family members ATAD3B and ATAD3C. Tissue-specific overexpression of bor, the Drosophila mutation homologous to the human c.1582C>T (p.Arg528Trp) variant, resulted in a dramatic decrease in mitochondrial content, aberrant mitochondrial morphology, and increased autophagy. Homozygous null bor larvae showed a significant decrease of mitochondria, while overexpression of bor resulted in larger, elongated mitochondria. Finally, fibroblasts of an affected individual exhibited increased mitophagy. We conclude that the p.Arg528Trp variant functions through a dominant-negative mechanism that results in small mitochondria that trigger mitophagy, resulting in a reduction in mitochondrial content. ATAD3A variation represents an additional link between mitochondrial dynamics and recognizable neurological syndromes, as seen with MFN2, OPA1, DNM1L, and STAT2 mutations.

}, keywords = {Adenosine Triphosphatases, Adult, Alleles, Animals, ATPases Associated with Diverse Cellular Activities, Axons, Cardiomyopathies, Child, Child, Preschool, Developmental Disabilities, DNA Copy Number Variations, Drosophila melanogaster, Female, Fibroblasts, Homozygote, Humans, Infant, Infant, Newborn, Male, Membrane Proteins, Mitochondria, Mitochondrial Proteins, Muscle Hypotonia, Muscles, Mutation, Nervous System Diseases, Neurons, Optic Atrophy, Phenotype, Polymorphism, Single Nucleotide, Syndrome, Young Adult}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2016.08.007}, author = {Harel, Tamar and Yoon, Wan Hee and Garone, Caterina and Gu, Shen and Coban-Akdemir, Zeynep and Eldomery, Mohammad K and Posey, Jennifer E and Jhangiani, Shalini N and Rosenfeld, Jill A and Cho, Megan T and Fox, Stephanie and Withers, Marjorie and Brooks, Stephanie M and Chiang, Theodore and Duraine, Lita and Erdin, Serkan and Yuan, Bo and Shao, Yunru and Moussallem, Elie and Lamperti, Costanza and Donati, Maria A and Smith, Joshua D and McLaughlin, Heather M and Eng, Christine M and Walkiewicz, Magdalena and Xia, Fan and Pippucci, Tommaso and Magini, Pamela and Seri, Marco and Zeviani, Massimo and Hirano, Michio and Hunter, Jill V and Srour, Myriam and Zanigni, Stefano and Lewis, Richard Alan and Muzny, Donna M and Lotze, Timothy E and Boerwinkle, Eric and Gibbs, Richard A and Hickey, Scott E and Graham, Brett H and Yang, Yaping and Buhas, Daniela and Martin, Donna M and Potocki, Lorraine and Graziano, Claudio and Bellen, Hugo J and Lupski, James R} } @article {196, title = {Mutations in RAD21 disrupt regulation of APOB in patients with chronic intestinal pseudo-obstruction.}, journal = {Gastroenterology}, volume = {148}, year = {2015}, month = {2015 Apr}, pages = {771-782.e11}, abstract = {

BACKGROUND \& AIMS: Chronic intestinal pseudo-obstruction (CIPO) is characterized by severe intestinal dysmotility that mimics a mechanical subocclusion with no~evidence of gut obstruction. We searched for genetic variants associated with CIPO to increase our understanding of its pathogenesis and to identify potential biomarkers.

METHODS: We performed whole-exome sequencing of genomic DNA from patients with familial CIPO syndrome. Blood and lymphoblastoid cells were collected from patients and controls (individuals without CIPO); levels of messenger RNA (mRNA) and proteins were analyzed by quantitative reverse-transcription polymerase chain reaction, immunoblot, and mobility shift assays. Complementary DNAs were transfected into HEK293 cells. Expression of rad21 was suppressed in zebrafish embryos using a splice-blocking morpholino (rad21a). Gut tissues were collected and analyzed.

RESULTS: We identified a homozygous mutation (p.622, encodes Ala>Thr) in RAD21 in patients from a consanguineous family with CIPO. Expression of RUNX1, a target of RAD21, was reduced in cells from patients with CIPO compared with controls. In zebrafish, suppression of rad21a reduced expression of runx1; this phenotype was corrected by injection of human RAD21 mRNA, but not with the mRNA from the mutated p.622 allele. rad21a Morpholino zebrafish had delayed intestinal transit and greatly reduced numbers of enteric neurons, similar to patients with CIPO. This defect was greater in zebrafish with suppressed expression of ret and rad21, indicating their interaction in the regulation of gut neurogenesis. The promoter region of APOB bound RAD21 but not RAD21 p.622 Ala>Thr; expression of wild-type RAD21 in HEK293 cells repressed expression of APOB, compared with control vector. The gut-specific isoform of APOB (APOB48) is overexpressed in sera from patients with CIPO who carry the RAD21 mutation. APOB48 also is overexpressed in sporadic CIPO in sera and gut biopsy specimens.

CONCLUSIONS: Some patients with CIPO carry mutations in RAD21 that disrupt the ability of its product to regulate genes such as RUNX1 and APOB. Reduced expression of rad21 in zebrafish, and dysregulation of these target genes, disrupts intestinal transit and the development of enteric neurons.

}, keywords = {Adult, Animals, Apolipoprotein B-100, Case-Control Studies, Cell Cycle Proteins, Chronic Disease, Core Binding Factor Alpha 2 Subunit, Enteric Nervous System, Female, Gastrointestinal Motility, Gene Expression Profiling, Gene Knockdown Techniques, HEK293 Cells, Humans, Intestinal Pseudo-Obstruction, Male, Middle Aged, Nuclear Proteins, Phosphoproteins, RNA, Messenger, Sequence Analysis, DNA, Young Adult, Zebrafish, Zebrafish Proteins}, issn = {1528-0012}, doi = {10.1053/j.gastro.2014.12.034}, author = {Bonora, Elena and Bianco, Francesca and Cordeddu, Lina and Bamshad, Michael and Francescatto, Ludmila and Dowless, Dustin and Stanghellini, Vincenzo and Cogliandro, Rosanna F and Lindberg, Greger and Mungan, Zeynel and Cefle, Kivanc and Ozcelik, Tayfun and Palanduz, Sukru and Ozturk, Sukru and Gedikbasi, Asuman and Gori, Alessandra and Pippucci, Tommaso and Graziano, Claudio and Volta, Umberto and Caio, Giacomo and Barbara, Giovanni and D{\textquoteright}Amato, Mauro and Seri, Marco and Katsanis, Nicholas and Romeo, Giovanni and De Giorgio, Roberto} }