@article {806, title = {Biallelic loss of function variants in SYT2 cause a treatable congenital onset presynaptic myasthenic syndrome.}, journal = {Am J Med Genet A}, volume = {182}, year = {2020}, month = {2020 10}, pages = {2272-2283}, abstract = {

Synaptotagmins are integral synaptic vesicle membrane proteins that function as calcium sensors and regulate neurotransmitter release at the presynaptic nerve terminal. Synaptotagmin-2 (SYT2), is the major isoform expressed at the neuromuscular junction. Recently, dominant missense variants in SYT2 have been reported as a rare cause of distal motor neuropathy and myasthenic syndrome, manifesting with stable or slowly progressive distal weakness of variable severity along with presynaptic NMJ impairment. These variants are thought to have a dominant-negative effect on synaptic vesicle exocytosis, although the precise pathomechanism remains to be elucidated. Here we report seven patients of five families, with biallelic loss of function variants in SYT2, clinically manifesting with a remarkably consistent phenotype of severe congenital onset hypotonia and weakness, with variable degrees of respiratory involvement. Electrodiagnostic findings were consistent with a presynaptic congenital myasthenic syndrome (CMS) in some. Treatment with an acetylcholinesterase inhibitor pursued in three patients showed clinical improvement with increased strength and function. This series further establishes SYT2 as a CMS-disease gene and expands its clinical and genetic spectrum to include recessive loss-of-function variants, manifesting as a severe congenital onset presynaptic CMS with potential treatment implications.

}, keywords = {Adolescent, Child, Child, Preschool, Female, Genetic Predisposition to Disease, Humans, Male, Muscle Hypotonia, Muscle Weakness, Mutation, Missense, Myasthenic Syndromes, Congenital, Pedigree, Phenotype, Synaptic Transmission, Synaptotagmin II}, issn = {1552-4833}, doi = {10.1002/ajmg.a.61765}, author = {Donkervoort, Sandra and Mohassel, Payam and Laugwitz, Lucia and Zaki, MAH S and Kamsteeg, Erik-Jan and Maroofian, Reza and Chao, Katherine R and Verschuuren-Bemelmans, Corien C and Horber, Veronka and Fock, Annemarie J M and McCarty, Riley M and Jain, Minal S and Biancavilla, Victoria and McMacken, Grace and Nalls, Matthew and Voermans, Nicol C and Elbendary, Hasnaa M and Snyder, Molly and Cai, Chunyu and Lehky, Tanya J and Stanley, Valentina and Iannaccone, Susan T and Foley, A Reghan and Lochm{\"u}ller, Hanns and Gleeson, Joseph and Houlden, Henry and Haack, Tobias B and Horvath, Rita and B{\"o}nnemann, Carsten G} } @article {451, title = {Congenital Titinopathy: Comprehensive characterization and pathogenic insights.}, journal = {Ann Neurol}, volume = {83}, year = {2018}, month = {2018 Jun}, pages = {1105-1124}, abstract = {

OBJECTIVE: Comprehensive clinical characterization of congenital titinopathy to facilitate diagnosis and management of this important emerging disorder.

METHODS: Using massively parallel sequencing we identified 30 patients from 27 families with 2 pathogenic nonsense, frameshift and/or splice site TTN mutations in trans. We then undertook a detailed analysis of the clinical, histopathological and imaging features of these patients.

RESULTS: All patients had prenatal or early onset hypotonia and/or congenital contractures. None had ophthalmoplegia. Scoliosis and respiratory insufficiency typically developed early and progressed rapidly, whereas limb weakness was often slowly progressive, and usually did not prevent independent walking. Cardiac involvement was present in 46\% of patients. Relatives of 2 patients had dilated cardiomyopathy. Creatine kinase levels were normal to moderately elevated. Increased fiber size variation, internalized nuclei and cores were common histopathological abnormalities. Cap-like regions, whorled or ring fibers, and mitochondrial accumulations were also observed. Muscle magnetic resonance imaging showed gluteal, hamstring and calf muscle involvement. Western blot analysis showed a near-normal sized titin protein in all samples. The presence of 2 mutations predicted to impact both N2BA and N2B cardiac isoforms appeared to be associated with greatest risk of cardiac involvement. One-third of patients had 1 mutation predicted to impact exons present in fetal skeletal muscle, but not included within the mature skeletal muscle isoform transcript. This strongly suggests developmental isoforms are involved in the pathogenesis of this congenital/early onset disorder.

INTERPRETATION: This detailed clinical reference dataset will greatly facilitate diagnostic confirmation and management of patients, and has provided important insights into disease pathogenesis. Ann Neurol 2018;83:1105-1124.

}, issn = {1531-8249}, doi = {10.1002/ana.25241}, author = {Oates, Emily C and Jones, Kristi J and Donkervoort, Sandra and Charlton, Amanda and Brammah, Susan and Smith, John E and Ware, James S and Yau, Kyle S and Swanson, Lindsay C and Whiffin, Nicola and Peduto, Anthony J and Bournazos, Adam and Waddell, Leigh B and Farrar, Michelle A and Sampaio, Hugo A and Teoh, Hooi Ling and Lamont, Phillipa J and Mowat, David and Fitzsimons, Robin B and Corbett, Alastair J and Ryan, Monique M and O{\textquoteright}Grady, Gina L and Sandaradura, Sarah A and Ghaoui, Roula and Joshi, Himanshu and Marshall, Jamie L and Nolan, Melinda A and Kaur, Simranpreet and Punetha, Jaya and Topf, Ana and Harris, Elizabeth and Bakshi, Madhura and Genetti, Casie A and Marttila, Minttu and Werlauff, Ulla and Streichenberger, Nathalie and Pestronk, Alan and Mazanti, Ingrid and Pinner, Jason R and Vuillerot, Carole and Grosmann, Carla and Camacho, Ana and Mohassel, Payam and Leach, Meganne E and Foley, A Reghan and Bharucha-Goebel, Diana and Collins, James and Connolly, Anne M and Gilbreath, Heather R and Iannaccone, Susan T and Castro, Diana and Cummings, Beryl B and Webster, Richard I and Lazaro, Le{\"\i}la and Vissing, John and Coppens, Sandra and Deconinck, Nicolas and Luk, Ho-Ming and Thomas, Neil H and Foulds, Nicola C and Illingworth, Marjorie A and Ellard, Sian and McLean, Catriona A and Phadke, Rahul and Ravenscroft, Gianina and Witting, Nanna and Hackman, Peter and Richard, Isabelle and Cooper, Sandra T and Kamsteeg, Erik-Jan and Hoffman, Eric P and Bushby, Kate and Straub, Volker and Udd, Bjarne and Ferreiro, Ana and North, Kathryn N and Clarke, Nigel F and Lek, Monkol and Beggs, Alan H and B{\"o}nnemann, Carsten G and MacArthur, Daniel G and Granzier, Henk and Davis, Mark R and Laing, Nigel G} } @article {560, title = {Loss of tubulin deglutamylase CCP1 causes infantile-onset neurodegeneration.}, journal = {EMBO J}, volume = {37}, year = {2018}, month = {2018 Dec 03}, abstract = {

A set of glutamylases and deglutamylases controls levels of tubulin polyglutamylation, a prominent post-translational modification of neuronal microtubules. Defective tubulin polyglutamylation was first linked to neurodegeneration in the () mouse, which lacks deglutamylase CCP1, displays massive cerebellar atrophy, and accumulates abnormally glutamylated tubulin in degenerating neurons. We found biallelic rare and damaging variants in the gene encoding CCP1 in 13 individuals with infantile-onset neurodegeneration and confirmed the absence of functional CCP1 along with dysregulated tubulin polyglutamylation. The human disease mainly affected the cerebellum, spinal motor neurons, and peripheral nerves. We also demonstrate previously unrecognized peripheral nerve and spinal motor neuron degeneration in mice, which thus recapitulated key features of the human disease. Our findings link human neurodegeneration to tubulin polyglutamylation, entailing this post-translational modification as a potential target for drug development for neurodegenerative disorders.

}, issn = {1460-2075}, doi = {10.15252/embj.2018100540}, author = {Shashi, Vandana and Magiera, Maria M and Klein, Dennis and Zaki, Maha and Schoch, Kelly and Rudnik-Sch{\"o}neborn, Sabine and Norman, Andrew and Lopes Abath Neto, Osorio and Dusl, Marina and Yuan, Xidi and Bartesaghi, Luca and De Marco, Patrizia and Alfares, Ahmed A and Marom, Ronit and Arold, Stefan T and Guzm{\'a}n-Vega, Francisco J and Pena, Loren Dm and Smith, Edward C and Steinlin, Maja and Babiker, Mohamed Oe and Mohassel, Payam and Foley, A Reghan and Donkervoort, Sandra and Kaur, Rupleen and Ghosh, Partha S and Stanley, Valentina and Musaev, Damir and Nava, Caroline and Mignot, Cyril and Keren, Boris and Scala, Marcello and Tassano, Elisa and Picco, Paolo and Doneda, Paola and Fiorillo, Chiara and Issa, Mahmoud Y and Alassiri, Ali and Alahmad, Ahmed and Gerard, Amanda and Liu, Pengfei and Yang, Yaping and Ertl-Wagner, Birgit and Kranz, Peter G and Wentzensen, Ingrid M and Stucka, Rolf and Stong, Nicholas and Allen, Andrew S and Goldstein, David B and Schoser, Benedikt and R{\"o}sler, Kai M and Alfadhel, Majid and Capra, Valeria and Chrast, Roman and Strom, Tim M and Kamsteeg, Erik-Jan and B{\"o}nnemann, Carsten G and Gleeson, Joseph G and Martini, Rudolf and Janke, Carsten and Senderek, Jan} } @article {453, title = {High Rate of Recurrent De Novo Mutations in Developmental and Epileptic Encephalopathies.}, journal = {Am J Hum Genet}, volume = {101}, year = {2017}, month = {2017 Nov 02}, pages = {664-685}, abstract = {

Developmental and epileptic encephalopathy (DEE) is a group of conditions characterized by the co-occurrence of epilepsy and intellectual disability (ID), typically with developmental plateauing or regression associated with frequent epileptiform activity. The cause of DEE remains unknown in the majority of cases. We performed whole-genome sequencing (WGS) in 197 individuals with unexplained DEE and pharmaco-resistant seizures and in their unaffected parents. We focused our attention on de novo mutations (DNMs) and identified candidate genes containing such variants. We sought to identify additional subjects with DNMs in these genes by performing targeted sequencing in another series of individuals with DEE and by mining various sequencing datasets. We also performed meta-analyses to document enrichment of DNMs in candidate genes by leveraging our WGS dataset with those of several DEE and ID series. By combining these strategies, we were able to provide a causal link between DEE and the following genes: NTRK2, GABRB2, CLTC, DHDDS, NUS1, RAB11A, GABBR2, and SNAP25. Overall, we established a molecular diagnosis in 63/197 (32\%) individuals in our WGS series. The main cause of DEE in these individuals was de novo point mutations (53/63 solved cases), followed by inherited mutations (6/63 solved cases) and de novo CNVs (4/63 solved cases). De novo missense variants explained a larger proportion of individuals in our series than in other series that were primarily ascertained because of ID. Moreover, these DNMs were more frequently recurrent than those identified in ID series. These observations indicate that the genetic landscape of DEE might be different from that of ID without epilepsy.

}, keywords = {Brain Diseases, Child, Child, Preschool, Epilepsy, Female, Genome, Human, Genome-Wide Association Study, Humans, Intellectual Disability, Male, Mutation, Recurrence, Seizures}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.09.008}, author = {Hamdan, Fadi F and Myers, Candace T and Cossette, Patrick and Lemay, Philippe and Spiegelman, Dan and Laporte, Alexandre Dionne and Nassif, Christina and Diallo, Ousmane and Monlong, Jean and Cadieux-Dion, Maxime and Dobrzeniecka, Sylvia and Meloche, Caroline and Retterer, Kyle and Cho, Megan T and Rosenfeld, Jill A and Bi, Weimin and Massicotte, Christine and Miguet, Marguerite and Brunga, Ledia and Regan, Brigid M and Mo, Kelly and Tam, Cory and Schneider, Amy and Hollingsworth, Georgie and FitzPatrick, David R and Donaldson, Alan and Canham, Natalie and Blair, Edward and Kerr, Bronwyn and Fry, Andrew E and Thomas, Rhys H and Shelagh, Joss and Hurst, Jane A and Brittain, Helen and Blyth, Moira and Lebel, Robert Roger and Gerkes, Erica H and Davis-Keppen, Laura and Stein, Quinn and Chung, Wendy K and Dorison, Sara J and Benke, Paul J and Fassi, Emily and Corsten-Janssen, Nicole and Kamsteeg, Erik-Jan and Mau-Them, Frederic T and Bruel, Ange-Line and Verloes, Alain and {\~O}unap, Katrin and Wojcik, Monica H and Albert, Dara V F and Venkateswaran, Sunita and Ware, Tyson and Jones, Dean and Liu, Yu-Chi and Mohammad, Shekeeb S and Bizargity, Peyman and Bacino, Carlos A and Leuzzi, Vincenzo and Martinelli, Simone and Dallapiccola, Bruno and Tartaglia, Marco and Blumkin, Lubov and Wierenga, Klaas J and Purcarin, Gabriela and O{\textquoteright}Byrne, James J and Stockler, Sylvia and Lehman, Anna and Keren, Boris and Nougues, Marie-Christine and Mignot, Cyril and Auvin, St{\'e}phane and Nava, Caroline and Hiatt, Susan M and Bebin, Martina and Shao, Yunru and Scaglia, Fernando and Lalani, Seema R and Frye, Richard E and Jarjour, Imad T and Jacques, St{\'e}phanie and Boucher, Renee-Myriam and Riou, Emilie and Srour, Myriam and Carmant, Lionel and Lortie, Anne and Major, Philippe and Diadori, Paola and Dubeau, Fran{\c c}ois and D{\textquoteright}Anjou, Guy and Bourque, Guillaume and Berkovic, Samuel F and Sadleir, Lynette G and Campeau, Philippe M and Kibar, Zoha and Lafreni{\`e}re, Ronald G and Girard, Simon L and Mercimek-Mahmutoglu, Saadet and Boelman, Cyrus and Rouleau, Guy A and Scheffer, Ingrid E and Mefford, Heather C and Andrade, Danielle M and Rossignol, Elsa and Minassian, Berge A and Michaud, Jacques L} } @article {534, title = {Variants in SLC18A3, vesicular acetylcholine transporter, cause congenital myasthenic syndrome.}, journal = {Neurology}, volume = {87}, year = {2016}, month = {2016 Oct 04}, pages = {1442-1448}, abstract = {

OBJECTIVE: To describe the clinical and genetic characteristics of presynaptic congenital myasthenic syndrome secondary to biallelic variants in SLC18A3.

METHODS: Individuals from 2 families were identified with biallelic variants in SLC18A3, the gene encoding the vesicular acetylcholine transporter (VAChT), through whole-exome sequencing.

RESULTS: The patients demonstrated features seen in presynaptic congenital myasthenic syndrome, including ptosis, ophthalmoplegia, fatigable weakness, apneic crises, and deterioration of symptoms in cold water for patient 1. Both patients demonstrated moderate clinical improvement on pyridostigmine. Patient 1 had a broader phenotype, including learning difficulties and left ventricular dysfunction. Electrophysiologic studies were typical for a presynaptic defect. Both patients showed profound electrodecrement on low-frequency repetitive stimulation followed by a prolonged period of postactivation exhaustion. In patient 1, this was unmasked only after isometric contraction, a recognized feature of presynaptic disease, emphasizing the importance of activation procedures.

CONCLUSIONS: VAChT is responsible for uptake of acetylcholine into presynaptic vesicles. The clinical and electrographic characteristics of the patients described are consistent with previously reported mouse models of VAChT deficiency. These findings make it very likely that defects in VAChT due to variants in SLC18A3 are a cause of congenital myasthenic syndrome in humans.

}, keywords = {Adolescent, Child, Diagnosis, Differential, Female, Genetic Variation, Humans, Male, Myasthenic Syndromes, Congenital, Vesicular Acetylcholine Transport Proteins}, issn = {1526-632X}, doi = {10.1212/WNL.0000000000003179}, author = {O{\textquoteright}Grady, Gina L and Verschuuren, Corien and Yuen, Michaela and Webster, Richard and Menezes, Manoj and Fock, Johanna M and Pride, Natalie and Best, Heather A and Benavides Damm, Tatiana and Turner, Christian and Lek, Monkol and Engel, Andrew G and North, Kathryn N and Clarke, Nigel F and MacArthur, Daniel G and Kamsteeg, Erik-Jan and Cooper, Sandra T} }