@article {918, title = {De novo variants in SNAP25 cause an early-onset developmental and epileptic encephalopathy.}, journal = {Genet Med}, volume = {23}, year = {2021}, month = {2021 04}, pages = {653-660}, abstract = {

PURPOSE: This study aims to provide a comprehensive description of the phenotypic and genotypic spectrum of SNAP25 developmental and epileptic encephalopathy (SNAP25-DEE) by reviewing newly identified and previously reported individuals.

METHODS: Individuals harboring heterozygous missense or loss-of-function variants in SNAP25 were assembled through collaboration with international colleagues, matchmaking platforms, and literature review. For each individual, detailed phenotyping, classification, and structural modeling of the identified variant were performed.

RESULTS: The cohort comprises 23 individuals with pathogenic or likely pathogenic de novo variants in SNAP25. Intellectual disability and early-onset epilepsy were identified as the core symptoms of SNAP25-DEE, with recurrent findings of movement disorders, cerebral visual impairment, and brain atrophy. Structural modeling for all variants predicted possible functional defects concerning SNAP25 or impaired interaction with other components of the SNARE complex.

CONCLUSION: We provide a comprehensive description of SNAP25-DEE with intellectual disability and early-onset epilepsy mostly occurring before the age of two years. These core symptoms and additional recurrent phenotypes show an overlap to genes encoding other components or associated proteins of the SNARE complex such as STX1B, STXBP1, or VAMP2. Thus, these findings advance the concept of a group of neurodevelopmental disorders that may be termed "SNAREopathies."

}, keywords = {Brain Diseases, Child, Preschool, Epilepsy, Humans, Intellectual Disability, Neurodevelopmental Disorders, Phenotype, Synaptosomal-Associated Protein 25}, issn = {1530-0366}, doi = {10.1038/s41436-020-01020-w}, author = {Kl{\"o}ckner, Chiara and Sticht, Heinrich and Zacher, Pia and Popp, Bernt and Babcock, Holly E and Bakker, Dewi P and Barwick, Katy and Bonfert, Michaela V and B{\"o}nnemann, Carsten G and Brilstra, Eva H and Chung, Wendy K and Clarke, Angus J and Devine, Patrick and Donkervoort, Sandra and Fraser, Jamie L and Friedman, Jennifer and Gates, Alyssa and Ghoumid, Jamal and Hobson, Emma and Horvath, Gabriella and Keller-Ramey, Jennifer and Keren, Boris and Kurian, Manju A and Lee, Virgina and Leppig, Kathleen A and Lundgren, Johan and McDonald, Marie T and McLaughlin, Heather M and McTague, Amy and Mefford, Heather C and Mignot, Cyril and Mikati, Mohamad A and Nava, Caroline and Raymond, F Lucy and Sampson, Julian R and Sanchis-Juan, Alba and Shashi, Vandana and Shieh, Joseph T C and Shinawi, Marwan and Slavotinek, Anne and St{\"o}dberg, Tommy and Stong, Nicholas and Sullivan, Jennifer A and Taylor, Ashley C and Toler, Tomi L and van den Boogaard, Marie-Jos{\'e} and van der Crabben, Saskia N and van Gassen, Koen L I and van Jaarsveld, Richard H and Van Ziffle, Jessica and Wadley, Alexandrea F and Wagner, Matias and Wigby, Kristen and Wortmann, Saskia B and Zarate, Yuri A and M{\o}ller, Rikke S and Lemke, Johannes R and Platzer, Konrad} } @article {678, title = {Heterozygous Variants in KMT2E Cause a Spectrum of Neurodevelopmental Disorders and Epilepsy.}, journal = {Am J Hum Genet}, volume = {104}, year = {2019}, month = {2019 Jun 06}, pages = {1210-1222}, abstract = {

We delineate a KMT2E-related neurodevelopmental disorder on the basis of 38 individuals in 36 families. This study includes 31 distinct heterozygous variants in KMT2E (28 ascertained from Matchmaker Exchange and three previously reported), and four individuals with chromosome 7q22.2-22.23 microdeletions encompassing KMT2E (one previously reported). Almost all variants occurred de novo, and most were truncating. Most affected individuals with protein-truncating variants presented with mild intellectual disability. One-quarter of individuals met criteria for autism. Additional common features include macrocephaly, hypotonia, functional gastrointestinal abnormalities, and a subtle facial gestalt. Epilepsy was present in about one-fifth of individuals with truncating variants and was responsive to treatment with anti-epileptic medications in almost all. More than 70\% of the individuals were male, and expressivity was variable by sex; epilepsy was more common in females and autism more common in males. The four individuals with microdeletions encompassing KMT2E generally presented similarly to those with truncating variants, but the degree of developmental delay was greater. The group of four individuals with missense variants in KMT2E presented with the most severe developmental delays. Epilepsy was present in all individuals with missense variants, often manifesting as treatment-resistant infantile epileptic encephalopathy. Microcephaly was also common in this group. Haploinsufficiency versus gain-of-function or dominant-negative effects specific to these missense variants in KMT2E might explain this divergence in phenotype, but requires independent validation. Disruptive variants in KMT2E are an under-recognized cause of neurodevelopmental abnormalities.

}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2019.03.021}, author = {O{\textquoteright}Donnell-Luria, Anne H and Pais, Lynn S and Faundes, V{\'\i}ctor and Wood, Jordan C and Sveden, Abigail and Luria, Victor and Abou Jamra, Rami and Accogli, Andrea and Amburgey, Kimberly and Anderlid, Britt Marie and Azzarello-Burri, Silvia and Basinger, Alice A and Bianchini, Claudia and Bird, Lynne M and Buchert, Rebecca and Carr{\'e}, Wilfrid and Ceulemans, Sophia and Charles, Perrine and Cox, Helen and Culliton, Lisa and Curr{\`o}, Aurora and Demurger, Florence and Dowling, James J and Duban-Bedu, Benedicte and Dubourg, Christ{\`e}le and Eiset, Saga Elise and Escobar, Luis F and Ferrarini, Alessandra and Haack, Tobias B and Hashim, Mona and Heide, Solveig and Helbig, Katherine L and Helbig, Ingo and Heredia, Raul and H{\'e}ron, Delphine and Isidor, Bertrand and Jonasson, Amy R and Joset, Pascal and Keren, Boris and Kok, Fernando and Kroes, Hester Y and Lavillaureix, Alino{\"e} and Lu, Xin and Maas, Saskia M and Maegawa, Gustavo H B and Marcelis, Carlo L M and Mark, Paul R and Masruha, Marcelo R and McLaughlin, Heather M and McWalter, Kirsty and Melchinger, Esther U and Mercimek-Andrews, Saadet and Nava, Caroline and Pendziwiat, Manuela and Person, Richard and Ramelli, Gian Paolo and Ramos, Luiza L P and Rauch, Anita and Reavey, Caitlin and Renieri, Alessandra and Rie{\ss}, Angelika and Sanchez-Valle, Amarilis and Sattar, Shifteh and Saunders, Carol and Schwarz, Niklas and Smol, Thomas and Srour, Myriam and Steindl, Katharina and Syrbe, Steffen and Taylor, Jenny C and Telegrafi, Aida and Thiffault, Isabelle and Trauner, Doris A and van der Linden, Helio and van Koningsbruggen, Silvana and Villard, Laurent and Vogel, Ida and Vogt, Julie and Weber, Yvonne G and Wentzensen, Ingrid M and Widjaja, Elysa and Zak, Jaroslav and Baxter, Samantha and Banka, Siddharth and Rodan, Lance H} } @article {414, title = {De novo missense variants in PPP1CB are associated with intellectual disability and congenital heart disease.}, journal = {Hum Genet}, volume = {135}, year = {2016}, month = {2016 12}, pages = {1399-1409}, abstract = {

Intellectual disabilities are genetically heterogeneous and can be associated with congenital anomalies. Using whole-exome sequencing (WES), we identified five different de novo missense variants in the protein phosphatase-1 catalytic subunit beta (PPP1CB) gene in eight unrelated individuals who share an overlapping phenotype of dysmorphic features, macrocephaly, developmental delay or intellectual disability (ID), congenital heart disease, short stature, and skeletal and connective tissue abnormalities. Protein phosphatase-1 (PP1) is a serine/threonine-specific protein phosphatase involved in the dephosphorylation of a variety of proteins. The PPP1CB gene encodes a PP1 subunit that regulates the level of protein phosphorylation. All five altered amino acids we observed are highly conserved among the PP1 subunit family, and all are predicted to disrupt PP1 subunit binding and impair dephosphorylation. Our data suggest that our heterozygous de novo PPP1CB pathogenic variants are associated with syndromic intellectual disability.

}, keywords = {Adolescent, Adult, Child, Child, Preschool, Exome, Female, Genetic Association Studies, Genetic Predisposition to Disease, Heart Defects, Congenital, Humans, Intellectual Disability, Male, Mutation, Missense, Phosphorylation, Protein Phosphatase 1}, issn = {1432-1203}, doi = {10.1007/s00439-016-1731-1}, author = {Ma, Lijiang and Bayram, Yavuz and McLaughlin, Heather M and Cho, Megan T and Krokosky, Alyson and Turner, Clesson E and Lindstrom, Kristin and Bupp, Caleb P and Mayberry, Katey and Mu, Weiyi and Bodurtha, Joann and Weinstein, Veronique and Zadeh, Neda and Alcaraz, Wendy and Powis, Z{\"o}e and Shao, Yunru and Scott, Daryl A and Lewis, Andrea M and White, Janson J and Jhangiani, Shalani N and Gulec, Elif Yilmaz and Lalani, Seema R and Lupski, James R and Retterer, Kyle and Schnur, Rhonda E and Wentzensen, Ingrid M and Bale, Sherri and Chung, Wendy K} } @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} }