@article {690, title = {Bi-allelic GOT2 Mutations Cause a Treatable Malate-Aspartate Shuttle-Related Encephalopathy.}, journal = {Am J Hum Genet}, volume = {105}, year = {2019}, month = {2019 Sep 05}, pages = {534-548}, abstract = {

Early-infantile encephalopathies with epilepsy are devastating conditions mandating an accurate diagnosis to guide proper management. Whole-exome sequencing was used to investigate the disease etiology in four children from independent families with intellectual disability and epilepsy, revealing bi-allelic GOT2 mutations. In-depth metabolic studies in individual 1 showed low plasma serine, hypercitrullinemia, hyperlactatemia, and hyperammonemia. The epilepsy was serine and pyridoxine responsive. Functional consequences of observed mutations were tested by measuring enzyme activity and by cell and animal models. Zebrafish and mouse models were used to validate brain developmental and functional defects and to test therapeutic strategies. GOT2 encodes the mitochondrial glutamate oxaloacetate transaminase. GOT2 enzyme activity was deficient in fibroblasts with bi-allelic mutations. GOT2, a member of the malate-aspartate shuttle, plays an essential role in the intracellular NAD(H) redox balance. De novo serine biosynthesis was impaired in fibroblasts with GOT2 mutations and GOT2-knockout HEK293 cells. Correcting the highly oxidized cytosolic NAD-redox state by pyruvate~supplementation restored serine biosynthesis in GOT2-deficient cells. Knockdown of got2a in zebrafish resulted in a brain developmental defect associated with seizure-like electroencephalography spikes, which could be rescued by supplying pyridoxine in embryo water. Both pyridoxine and serine synergistically rescued embryonic developmental defects in zebrafish got2a morphants. The two treated individuals reacted favorably to their treatment. Our data provide a mechanistic basis for the biochemical abnormalities in GOT2 deficiency that may also hold for other MAS defects.

}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2019.07.015}, author = {van Karnebeek, Clara D M and Ramos, R{\'u}ben J and Wen, Xiao-Yan and Tarailo-Graovac, Maja and Gleeson, Joseph G and Skrypnyk, Cristina and Brand-Arzamendi, Koroboshka and Karbassi, Farhad and Issa, Mahmoud Y and van der Lee, Robin and Dr{\"o}gem{\"o}ller, Britt I and Koster, Janet and Rousseau, Justine and Campeau, Philippe M and Wang, Youdong and Cao, Feng and Li, Meng and Ruiter, Jos and Ciapaite, Jolita and Kluijtmans, Leo A J and Willemsen, Michel A A P and Jans, Judith J and Ross, Colin J and Wintjes, Liesbeth T and Rodenburg, Richard J and Huigen, Marleen C D G and Jia, Zhengping and Waterham, Hans R and Wasserman, Wyeth W and Wanders, Ronald J A and Verhoeven-Duif, Nanda M and Zaki, Maha S and Wevers, Ron A} } @article {589, title = {Missense Variants in the Histone Acetyltransferase Complex Component Gene TRRAP Cause Autism and Syndromic Intellectual Disability.}, journal = {Am J Hum Genet}, volume = {104}, year = {2019}, month = {2019 03 07}, pages = {530-541}, abstract = {

Acetylation of the lysine residues in histones and other DNA-binding proteins plays a major role in regulation of eukaryotic gene expression. This process is controlled by histone acetyltransferases (HATs/KATs) found in multiprotein complexes that are recruited to chromatin by the scaffolding subunit transformation/transcription domain-associated protein (TRRAP). TRRAP is evolutionarily conserved and is among the top five genes intolerant to missense variation. Through an international collaboration, 17 distinct de novo or apparently de novo variants were identified in TRRAP in 24 individuals. A strong genotype-phenotype correlation was observed with two distinct clinical spectra. The first is a complex, multi-systemic syndrome associated with various malformations of the brain, heart, kidneys, and genitourinary system and characterized by a wide range of intellectual functioning; a number of affected individuals have intellectual disability (ID) and markedly impaired basic life functions. Individuals with this phenotype had missense variants clustering around the c.3127G>A p.(Ala1043Thr) variant identified in five individuals. The second spectrum manifested with autism spectrum disorder (ASD) and/or ID and epilepsy. Facial dysmorphism was seen in both groups and included upslanted palpebral fissures, epicanthus, telecanthus, a wide nasal bridge and ridge, a broad and smooth philtrum, and a thin upper lip. RNA sequencing analysis of skin fibroblasts derived from affected individuals skin fibroblasts showed significant changes in the expression of several genes implicated in neuronal function and ion transport. Thus, we describe here the clinical spectrum associated with TRRAP pathogenic missense variants, and we suggest a genotype-phenotype correlation useful for clinical evaluation of the pathogenicity of the variants.

}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2019.01.010}, author = {Cogn{\'e}, Benjamin and Ehresmann, Sophie and Beauregard-Lacroix, Eliane and Rousseau, Justine and Besnard, Thomas and Garcia, Thomas and Petrovski, Slav{\'e} and Avni, Shiri and McWalter, Kirsty and Blackburn, Patrick R and Sanders, Stephan J and Uguen, K{\'e}vin and Harris, Jacqueline and Cohen, Julie S and Blyth, Moira and Lehman, Anna and Berg, Jonathan and Li, Mindy H and Kini, Usha and Joss, Shelagh and von der Lippe, Charlotte and Gordon, Christopher T and Humberson, Jennifer B and Robak, Laurie and Scott, Daryl A and Sutton, Vernon R and Skraban, Cara M and Johnston, Jennifer J and Poduri, Annapurna and Nordenskj{\"o}ld, Magnus and Shashi, Vandana and Gerkes, Erica H and Bongers, Ernie M H F and Gilissen, Christian and Zarate, Yuri A and Kvarnung, Malin and Lally, Kevin P and Kulch, Peggy A and Daniels, Brina and Hernandez-Garcia, Andres and Stong, Nicholas and McGaughran, Julie and Retterer, Kyle and Tveten, Kristian and Sullivan, Jennifer and Geisheker, Madeleine R and Stray-Pedersen, Asbjorg and Tarpinian, Jennifer M and Klee, Eric W and Sapp, Julie C and Zyskind, Jacob and Holla, {\O}ystein L and Bedoukian, Emma and Filippini, Francesca and Guimier, Anne and Picard, Arnaud and Busk, {\O}yvind L and Punetha, Jaya and Pfundt, Rolph and Lindstrand, Anna and Nordgren, Ann and Kalb, Fayth and Desai, Megha and Ebanks, Ashley Harmon and Jhangiani, Shalini N and Dewan, Tammie and Coban Akdemir, Zeynep H and Telegrafi, Aida and Zackai, Elaine H and Begtrup, Amber and Song, Xiaofei and Toutain, Annick and Wentzensen, Ingrid M and Odent, Sylvie and Bonneau, Dominique and Latypova, X{\'e}nia and Deb, Wallid and Redon, Sylvia and Bilan, Fr{\'e}d{\'e}ric and Legendre, Marine and Troyer, Caitlin and Whitlock, Kerri and Caluseriu, Oana and Murphree, Marine I and Pichurin, Pavel N and Agre, Katherine and Gavrilova, Ralitza and Rinne, Tuula and Park, Meredith and Shain, Catherine and Heinzen, Erin L and Xiao, Rui and Amiel, Jeanne and Lyonnet, Stanislas and Isidor, Bertrand and Biesecker, Leslie G and Lowenstein, Dan and Posey, Jennifer E and Denomm{\'e}-Pichon, Anne-Sophie and F{\'e}rec, Claude and Yang, Xiang-Jiao and Rosenfeld, Jill A and Gilbert-Dussardier, Brigitte and Audebert-Bellanger, S{\'e}verine and Redon, Richard and Stessman, Holly A F and Nellaker, Christoffer and Yang, Yaping and Lupski, James R and Goldstein, David B and Eichler, Evan E and Bolduc, Francois and B{\'e}zieau, St{\'e}phane and K{\"u}ry, S{\'e}bastien and Campeau, Philippe M} } @article {391, title = {Heterozygous variants in ACTL6A, encoding a component of the BAF complex, are associated with intellectual disability.}, journal = {Hum Mutat}, volume = {38}, year = {2017}, month = {2017 10}, pages = {1365-1371}, abstract = {

Pathogenic variants in genes encoding components of the BRG1-associated factor (BAF) chromatin remodeling complex have been associated with intellectual disability syndromes. We identified heterozygous, novel variants in ACTL6A, a gene encoding a component of the BAF complex, in three subjects with varying degrees of intellectual disability. Two subjects have missense variants affecting highly conserved amino acid residues within the actin-like domain. Missense mutations in the homologous region in yeast actin were previously reported to be dominant lethal and were associated with impaired binding of the human ACTL6A to β-actin and BRG1. A third subject has a splicing variant that creates an in-frame deletion. Our findings suggest that the variants identified in our subjects may have a deleterious effect on the function of the protein by disturbing the integrity of the BAF complex. Thus, ACTL6A gene mutation analysis should be considered in patients with intellectual disability, learning disabilities, or developmental language disorder.

}, keywords = {Actins, Adolescent, Child, Chromatin Assembly and Disassembly, Chromosomal Proteins, Non-Histone, DNA Helicases, DNA-Binding Proteins, Exome, Face, Female, Hand Deformities, Congenital, Heterozygote, Humans, Intellectual Disability, Male, Micrognathism, Multiprotein Complexes, Mutation, Missense, Nuclear Proteins, Protein Binding, Transcription Factors}, issn = {1098-1004}, doi = {10.1002/humu.23282}, author = {Marom, Ronit and Jain, Mahim and Burrage, Lindsay C and Song, I-Wen and Graham, Brett H and Brown, Chester W and Stevens, Servi J C and Stegmann, Alexander P A and Gunter, Andrew T and Kaplan, Julie D and Gavrilova, Ralitza H and Shinawi, Marwan and Rosenfeld, Jill A and Bae, Yangjin and Tran, Alyssa A and Chen, Yuqing and Lu, James T and Gibbs, Richard A and Eng, Christine and Yang, Yaping and Rousseau, Justine and de Vries, Bert B A and Campeau, Philippe M and Lee, Brendan} } @article {422, title = {Mutations in Fibronectin Cause a Subtype of Spondylometaphyseal Dysplasia with "Corner Fractures".}, journal = {Am J Hum Genet}, volume = {101}, year = {2017}, month = {2017 Nov 02}, pages = {815-823}, abstract = {

Fibronectin is a master organizer of extracellular matrices (ECMs) and promotes the assembly of collagens, fibrillin-1, and other proteins. It is also known to play roles in skeletal tissues through its secretion by osteoblasts, chondrocytes, and mesenchymal cells. Spondylometaphyseal dysplasias (SMDs) comprise a diverse group of skeletal dysplasias and often manifest as short stature, growth-plate irregularities, and vertebral anomalies, such as scoliosis. By comparing the exomes of individuals with SMD with the radiographic appearance of "corner fractures" at metaphyses, we identified three individuals with fibronectin (FN1) variants affecting highly conserved residues. Furthermore, using matching tools and the SkelDys emailing list, we identified other individuals with de novo~FN1 variants and a similar phenotype. The severe scoliosis in most individuals and rare developmental coxa vara distinguish individuals with FN1 mutations from those with classical Sutcliffe-type SMD. To study functional consequences of these FN1 mutations on the protein level, we introduced three disease-associated missense variants (p.Cys87Phe [c.260G>T], p.Tyr240Asp [c.718T>G], and p.Cys260Gly [c.778T>G]) into a recombinant secreted N-terminal 70~kDa fragment (rF70K) and the full-length fibronectin (rFN). The wild-type rF70K and rFN were secreted into the culture medium, whereas all mutant proteins were either not secreted or secreted at significantly lower amounts. Immunofluorescence analysis demonstrated increased intracellular retention of the mutant proteins. In summary, FN1 mutations that cause defective fibronectin secretion are found in SMD, and we thus provide additional evidence for a critical function of fibronectin in cartilage and bone.

}, keywords = {Adolescent, Adult, Bone and Bones, Bone Diseases, Developmental, Cartilage, Child, Child, Preschool, Exome, Female, Fibronectins, Fractures, Bone, Humans, Male, Mutation, Osteochondrodysplasias, Phenotype, Scoliosis}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.09.019}, author = {Lee, Chae Syng and Fu, He and Baratang, Nissan and Rousseau, Justine and Kumra, Heena and Sutton, V Reid and Niceta, Marcello and Ciolfi, Andrea and Yamamoto, Guilherme and Bertola, D{\'e}bora and Marcelis, Carlo L and Lugtenberg, Dorien and Bartuli, Andrea and Kim, Choel and Hoover-Fong, Julie and Sobreira, Nara and Pauli, Richard and Bacino, Carlos and Krakow, Deborah and Parboosingh, Jillian and Yap, Patrick and Kariminejad, Ariana and McDonald, Marie T and Aracena, Mariana I and Lausch, Ekkehart and Unger, Sheila and Superti-Furga, Andrea and Lu, James T and Cohn, Dan H and Tartaglia, Marco and Lee, Brendan H and Reinhardt, Dieter P and Campeau, Philippe M} } @article {493, title = {Mutations in GPAA1, Encoding a GPI Transamidase Complex Protein, Cause Developmental Delay, Epilepsy, Cerebellar Atrophy, and Osteopenia.}, journal = {Am J Hum Genet}, volume = {101}, year = {2017}, month = {2017 Nov 02}, pages = {856-865}, abstract = {

Approximately one in every 200 mammalian proteins is anchored to the cell membrane through a glycosylphosphatidylinositol (GPI) anchor. These proteins play important roles notably in neurological development and function. To date, more than 20 genes have been implicated in the biogenesis of GPI-anchored proteins. GPAA1 (glycosylphosphatidylinositol anchor attachment 1) is an essential component of the transamidase complex along with PIGK, PIGS, PIGT, and PIGU (phosphatidylinositol-glycan biosynthesis classes K, S, T, and U, respectively). This complex orchestrates the attachment of the GPI anchor to the C terminus of precursor proteins in the endoplasmic reticulum. Here, we report bi-allelic mutations in GPAA1 in ten individuals from five families. Using whole-exome sequencing, we identified two frameshift mutations (c.981_993del [p.Gln327Hisfs102] and c.920delG [p.Gly307Alafs11]), one intronic splicing mutation (c.1164+5C>T), and six missense mutations (c.152C>T [p.Ser51Leu], c.160_161delinsAA [p.Ala54Asn], c.527G>C [p.Trp176Ser], c.869T>C [p.Leu290Pro], c.872T>C [p.Leu291Pro], and c.1165G>C [p.Ala389Pro]). Most individuals presented with global developmental delay, hypotonia, early-onset seizures, cerebellar atrophy, and osteopenia. The splicing mutation was found to decrease GPAA1 mRNA. Moreover, flow-cytometry analysis of five available individual samples showed that several GPI-anchored proteins had decreased cell-surface abundance in leukocytes (FLAER, CD16, and CD59) or fibroblasts (CD73 and CD109). Transduction of fibroblasts with a lentivirus encoding the wild-type protein partially rescued the deficiency of GPI-anchored proteins. These findings highlight the role of the transamidase complex in the development and function of the cerebellum and the skeletal system.

}, keywords = {Acyltransferases, Adolescent, Adult, Alleles, Atrophy, Bone Diseases, Metabolic, Cerebellum, Child, Child, Preschool, Developmental Disabilities, Epilepsy, Exome, Female, Fibroblasts, Glycosylphosphatidylinositols, Humans, Male, Membrane Glycoproteins, Muscle Hypotonia, Mutation, Pedigree, RNA, Messenger, Seizures}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.09.020}, author = {Nguyen, Thi Tuyet Mai and Murakami, Yoshiko and Sheridan, Eamonn and Ehresmann, Sophie and Rousseau, Justine and St-Denis, Anik and Chai, Guoliang and Ajeawung, Norbert F and Fairbrother, Laura and Reimschisel, Tyler and Bateman, Alexandra and Berry-Kravis, Elizabeth and Xia, Fan and Tardif, Jessica and Parry, David A and Logan, Clare V and Diggle, Christine and Bennett, Christopher P and Hattingh, Louise and Rosenfeld, Jill A and Perry, Michael Scott and Parker, Michael J and Le Deist, Fran{\c c}oise and Zaki, Maha S and Ignatius, Erika and Isohanni, Pirjo and L{\"o}nnqvist, Tuula and Carroll, Christopher J and Johnson, Colin A and Gleeson, Joseph G and Kinoshita, Taroh and Campeau, Philippe M} }