@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 = {<p>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.</p>},
	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 {455,
	title = {Variants in the Oxidoreductase PYROXD1 Cause Early-Onset Myopathy with Internalized Nuclei and Myofibrillar Disorganization.},
	journal = {Am J Hum Genet},
	volume = {99},
	year = {2016},
	month = {2016 Nov 03},
	pages = {1086-1105},
	abstract = {<p>This study establishes PYROXD1 variants as a cause of early-onset myopathy and uses biospecimens and cell lines, yeast, and zebrafish models to elucidate the fundamental role of PYROXD1 in skeletal muscle. Exome sequencing identified recessive variants in PYROXD1 in nine probands from five families. Affected individuals presented in infancy or childhood with slowly progressive proximal and distal weakness, facial weakness, nasal speech, swallowing difficulties, and normal to moderately elevated creatine kinase. Distinctive histopathology showed abundant internalized nuclei, myofibrillar disorganization, desmin-positive inclusions, and thickened Z-bands. PYROXD1 is a nuclear-cytoplasmic pyridine nucleotide-disulphide reductase (PNDR). PNDRs are flavoproteins (FAD-binding) and catalyze pyridine-nucleotide-dependent (NAD/NADH) reduction of thiol residues in other proteins. Complementation experiments in yeast lacking glutathione reductase glr1 show that human PYROXD1 has reductase activity that is strongly impaired by the disease-associated missense mutations. Immunolocalization studies in human muscle and zebrafish myofibers demonstrate that PYROXD1 localizes to the nucleus and to striated sarcomeric compartments. Zebrafish with ryroxD1 knock-down recapitulate features of PYROXD1 myopathy with sarcomeric disorganization, myofibrillar aggregates, and marked swimming defect. We characterize variants in the oxidoreductase PYROXD1 as a cause of early-onset myopathy with distinctive histopathology and introduce altered redox regulation as a primary cause of congenital muscle disease.</p>},
	keywords = {Amino Acid Sequence, Animals, Cell Nucleus, Cercopithecus aethiops, Cohort Studies, COS Cells, Creatine Kinase, Cytoplasm, Distal Myopathies, ELAV-Like Protein 4, Female, Flavoproteins, Gene Deletion, Genetic Variation, Genome-Wide Association Study, Glutathione Reductase, HEK293 Cells, Humans, Male, Muscle, Skeletal, Mutation, Missense, Myopathies, Structural, Congenital, Oxidoreductases, Pedigree, Protein Conformation, Saccharomyces cerevisiae Proteins, Zebrafish},
	issn = {1537-6605},
	doi = {10.1016/j.ajhg.2016.09.005},
	author = {O{\textquoteright}Grady, Gina L and Best, Heather A and Sztal, Tamar E and Schartner, Vanessa and Sanjuan-Vazquez, Myriam and Donkervoort, Sandra and Abath Neto, Osorio and Sutton, Roger Bryan and Ilkovski, Biljana and Romero, Norma Beatriz and Stojkovic, Tanya and Dastgir, Jahannaz and Waddell, Leigh B and Boland, Anne and Hu, Ying and Williams, Caitlin and Ruparelia, Avnika A and Maisonobe, Thierry and Peduto, Anthony J and Reddel, Stephen W and Lek, Monkol and Tukiainen, Taru and Cummings, Beryl B and Joshi, Himanshu and Nectoux, Juliette and Brammah, Susan and Deleuze, Jean-Fran{\c c}ois and Ing, Viola Oorschot and Ramm, Georg and Ardicli, Didem and Nowak, Kristen J and Talim, Beril and Topaloglu, Haluk and Laing, Nigel G and North, Kathryn N and MacArthur, Daniel G and Friant, Sylvie and Clarke, Nigel F and Bryson-Richardson, Robert J and B{\"o}nnemann, Carsten G and Laporte, Jocelyn and Cooper, Sandra T}
}
