@article {815, title = {Predominant and novel de novo variants in 29 individuals with ALG13 deficiency: Clinical description, biomarker status, biochemical analysis, and treatment suggestions.}, journal = {J Inherit Metab Dis}, volume = {43}, year = {2020}, month = {2020 11}, pages = {1333-1348}, abstract = {

Asparagine-linked glycosylation 13 homolog (ALG13) encodes a nonredundant, highly conserved, X-linked uridine diphosphate (UDP)-N-acetylglucosaminyltransferase required for the synthesis of lipid linked oligosaccharide precursor and proper N-linked glycosylation. De novo variants in ALG13 underlie a form of early infantile epileptic encephalopathy known as EIEE36, but given its essential role in glycosylation, it is also considered a congenital disorder of glycosylation (CDG), ALG13-CDG. Twenty-four previously reported ALG13-CDG cases had de novo variants, but surprisingly, unlike most forms of CDG, ALG13-CDG did not show the anticipated glycosylation defects, typically detected by altered transferrin glycosylation. Structural homology modeling of two recurrent de novo variants, p.A81T and p.N107S, suggests both are likely to impact the function of ALG13. Using a corresponding ALG13-deficient yeast strain, we show that expressing yeast ALG13 with either of the highly conserved hotspot variants rescues the observed growth defect, but not its glycosylation abnormality. We present molecular and clinical data on 29 previously unreported individuals with de novo variants in ALG13. This more than doubles the number of known cases. A key finding is that a vast majority of the individuals presents with West syndrome, a feature shared with other CDG types. Among these, the initial epileptic spasms best responded to adrenocorticotropic hormone or prednisolone, while clobazam and felbamate showed promise for continued epilepsy treatment. A ketogenic diet seems to play an important role in the treatment of these individuals.

}, issn = {1573-2665}, doi = {10.1002/jimd.12290}, author = {Ng, Bobby G and Eklund, Erik A and Shiryaev, Sergey A and Dong, Yin Y and Abbott, Mary-Alice and Asteggiano, Carla and Bamshad, Michael J and Barr, Eileen and Bernstein, Jonathan A and Chelakkadan, Shabeed and Christodoulou, John and Chung, Wendy K and Ciliberto, Michael A and Cousin, Janice and Gardiner, Fiona and Ghosh, Suman and Graf, William D and Grunewald, Stephanie and Hammond, Katherine and Hauser, Natalie S and Hoganson, George E and Houck, Kimberly M and Kohler, Jennefer N and Morava, Eva and Larson, Austin A and Liu, Pengfei and Madathil, Sujana and McCormack, Colleen and Meeks, Naomi J L and Miller, Rebecca and Monaghan, Kristin G and Nickerson, Deborah A and Palculict, Timothy Blake and Papazoglu, Gabriela Magali and Pletcher, Beth A and Scheffer, Ingrid E and Schenone, Andrea Beatriz and Schnur, Rhonda E and Si, Yue and Rowe, Leah J and Serrano Russi, Alvaro H and Russo, Rossana Sanchez and Thabet, Farouq and Tuite, Allysa and Villanueva, Mar{\'\i}a Mercedes and Wang, Raymond Y and Webster, Richard I and Wilson, Dorcas and Zalan, Alice and Wolfe, Lynne A and Rosenfeld, Jill A and Rhodes, Lindsay and Freeze, Hudson H} } @article {371, title = {Activation of a cryptic splice site in the mitochondrial elongation factor GFM1 causes combined OXPHOS deficiency.}, journal = {Mitochondrion}, volume = {34}, year = {2017}, month = {2017 05}, pages = {84-90}, abstract = {

We report the clinical, biochemical, and molecular findings in two brothers with encephalopathy and multi-systemic disease. Abnormal transferrin glycoforms were suggestive of a type I congenital disorder of glycosylation (CDG). While exome sequencing was negative for CDG related candidate genes, the testing revealed compound heterozygous mutations in the mitochondrial elongation factor G gene (GFM1). One of the mutations had been reported previously while the second, novel variant was found deep in intron 6, activating a cryptic splice site. Functional studies demonstrated decreased GFM1 protein levels, suggested disrupted assembly of mitochondrial complexes III and V and decreased activities of mitochondrial complexes I and IV, all indicating combined OXPHOS deficiency.

}, keywords = {Child, Child, Preschool, Congenital Abnormalities, Gene Expression, Humans, Infant, Infant, Newborn, Male, Mitochondrial Proteins, Oxidative Phosphorylation, Peptide Elongation Factor G, RNA Splice Sites}, issn = {1872-8278}, doi = {10.1016/j.mito.2017.02.004}, author = {Simon, Mariella T and Ng, Bobby G and Friederich, Marisa W and Wang, Raymond Y and Boyer, Monica and Kircher, Martin and Collard, Renata and Buckingham, Kati J and Chang, Richard and Shendure, Jay and Nickerson, Deborah A and Bamshad, Michael J and Van Hove, Johan L K and Freeze, Hudson H and Abdenur, Jose E} } @article {77, title = {ALG1-CDG: Clinical and Molecular Characterization of 39 Unreported Patients.}, journal = {Hum Mutat}, volume = {37}, year = {2016}, month = {2016 07}, pages = {653-60}, abstract = {

Congenital disorders of glycosylation (CDG) arise from pathogenic mutations in over 100 genes leading to impaired protein or lipid glycosylation. ALG1 encodes a β1,4 mannosyltransferase that catalyzes the addition of the first of nine mannose moieties to form a dolichol-lipid linked oligosaccharide intermediate required for proper N-linked glycosylation. ALG1 mutations cause a rare autosomal recessive disorder termed ALG1-CDG. To date 13 mutations in 18 patients from 14 families have been described with varying degrees of clinical severity. We identified and characterized 39 previously unreported cases of ALG1-CDG from 32 families and add 26 new mutations. Pathogenicity of each mutation was confirmed based on its inability to rescue impaired growth or hypoglycosylation of a standard biomarker in an alg1-deficient yeast strain. Using this approach we could not establish a rank order comparison of biomarker glycosylation and patient phenotype, but we identified mutations with a lethal outcome in the first two years of life. The recently identified protein-linked xeno-tetrasaccharide biomarker, NeuAc-Gal-GlcNAc2 , was seen in all 27 patients tested. Our study triples the number of known patients and expands the molecular and clinical correlates of this disorder.

}, keywords = {Biomarkers, Congenital Disorders of Glycosylation, Female, Genes, Lethal, Glycosylation, Humans, Male, Mannosyltransferases, Mutation, Polysaccharides, Sequence Analysis, DNA, Survival Analysis}, issn = {1098-1004}, doi = {10.1002/humu.22983}, author = {Ng, Bobby G and Shiryaev, Sergey A and Rymen, Daisy and Eklund, Erik A and Raymond, Kimiyo and Kircher, Martin and Abdenur, Jose E and Alehan, Fusun and Midro, Alina T and Bamshad, Michael J and Barone, Rita and Berry, Gerard T and Brumbaugh, Jane E and Buckingham, Kati J and Clarkson, Katie and Cole, F Sessions and O{\textquoteright}Connor, Shawn and Cooper, Gregory M and Van Coster, Rudy and Demmer, Laurie A and Diogo, Luisa and Fay, Alexander J and Ficicioglu, Can and Fiumara, Agata and Gahl, William A and Ganetzky, Rebecca and Goel, Himanshu and Harshman, Lyndsay A and He, Miao and Jaeken, Jaak and James, Philip M and Katz, Daniel and Keldermans, Liesbeth and Kibaek, Maria and Kornberg, Andrew J and Lachlan, Katherine and Lam, Christina and Yaplito-Lee, Joy and Nickerson, Deborah A and Peters, Heidi L and Race, Valerie and R{\'e}gal, Luc and Rush, Jeffrey S and Rutledge, S Lane and Shendure, Jay and Souche, Erika and Sparks, Susan E and Trapane, Pamela and Sanchez-Valle, Amarilis and Vilain, Eric and V{\o}llo, Arve and Waechter, Charles J and Wang, Raymond Y and Wolfe, Lynne A and Wong, Derek A and Wood, Tim and Yang, Amy C and Matthijs, Gert and Freeze, Hudson H} }