@article {804, title = {Loss of NARS1 impairs progenitor proliferation in cortical brain organoids and leads to microcephaly.}, journal = {Nat Commun}, volume = {11}, year = {2020}, month = {2020 08 12}, pages = {4038}, abstract = {

Asparaginyl-tRNA synthetase1 (NARS1) is a member of the ubiquitously expressed cytoplasmic Class IIa family of tRNA synthetases required for protein translation. Here, we identify biallelic missense and frameshift mutations in NARS1 in seven patients from three unrelated families with microcephaly and neurodevelopmental delay. Patient cells show reduced NARS1 protein, impaired NARS1 activity and impaired global protein synthesis. Cortical brain organoid modeling shows reduced proliferation of radial glial cells (RGCs), leading to smaller organoids characteristic of microcephaly. Single-cell analysis reveals altered constituents of both astrocytic and RGC lineages, suggesting a requirement for NARS1 in RGC proliferation. Our findings demonstrate that NARS1 is required to meet protein synthetic needs and to support RGC proliferation in human brain development.

}, keywords = {Adolescent, Adult, Aspartate-tRNA Ligase, Base Sequence, Cell Differentiation, Cell Proliferation, Cell Size, Cell Survival, Cerebral Cortex, Child, Family, Female, Fibroblasts, HEK293 Cells, Humans, Induced Pluripotent Stem Cells, Ki-67 Antigen, Male, Microcephaly, Mutation, Neural Stem Cells, Neuroglia, Organoids, Pedigree, RNA, Transfer, Amino Acyl, Young Adult}, issn = {2041-1723}, doi = {10.1038/s41467-020-17454-4}, author = {Wang, Lu and Li, Zhen and Sievert, David and Smith, Desir{\'e}e E C and Mendes, Marisa I and Chen, Dillon Y and Stanley, Valentina and Ghosh, Shereen and Wang, Yulu and Kara, Majdi and Aslanger, Ayca Dilruba and Rosti, Rasim O and Houlden, Henry and Salomons, Gajja S and Gleeson, Joseph G} } @article {828, title = {Loss of the neural-specific BAF subunit ACTL6B relieves repression of early response genes and causes recessive autism.}, journal = {Proc Natl Acad Sci U S A}, volume = {117}, year = {2020}, month = {2020 05 05}, pages = {10055-10066}, abstract = {

Synaptic activity in neurons leads to the rapid activation of genes involved in mammalian behavior. ATP-dependent chromatin remodelers such as the BAF complex contribute to these responses and are generally thought to activate transcription. However, the mechanisms keeping such "early activation" genes silent have been a mystery. In the course of investigating Mendelian recessive autism, we identified six families with segregating loss-of-function mutations in the neuronal BAF (nBAF) subunit (originally named ). Accordingly, was the most significantly mutated gene in the Simons Recessive Autism Cohort. At least 14 subunits of the nBAF complex are mutated in autism, collectively making it a major contributor to autism spectrum disorder (ASD). Patient mutations destabilized ACTL6B protein in neurons and rerouted dendrites to the wrong glomerulus in the fly olfactory system. Humans and mice lacking showed corpus callosum hypoplasia, indicating a conserved role for in facilitating neural connectivity. knockout mice on two genetic backgrounds exhibited ASD-related behaviors, including social and memory impairments, repetitive behaviors, and hyperactivity. Surprisingly, mutation of relieved repression of early response genes including AP1 transcription factors (, , , and ), increased chromatin accessibility at AP1 binding sites, and transcriptional changes in late response genes associated with early response transcription factor activity. loss is thus an important cause of recessive ASD, with impaired neuron-specific chromatin repression indicated as a potential mechanism.

}, keywords = {Actins, Adenosine Triphosphate, Animals, Autism Spectrum Disorder, Behavior, Animal, Chromatin, Chromatin Assembly and Disassembly, Chromosomal Proteins, Non-Histone, Chromosome Pairing, Corpus Callosum, Dendrites, Disease Models, Animal, DNA-Binding Proteins, Gene Expression Regulation, Hippocampus, Humans, Mice, Mice, Knockout, Mutation, Neurons, Transcription Factors}, issn = {1091-6490}, doi = {10.1073/pnas.1908238117}, author = {Wenderski, Wendy and Wang, Lu and Krokhotin, Andrey and Walsh, Jessica J and Li, Hongjie and Shoji, Hirotaka and Ghosh, Shereen and George, Renee D and Miller, Erik L and Elias, Laura and Gillespie, Mark A and Son, Esther Y and Staahl, Brett T and Baek, Seung Tae and Stanley, Valentina and Moncada, Cynthia and Shipony, Zohar and Linker, Sara B and Marchetto, Maria C N and Gage, Fred H and Chen, Dillon and Sultan, Tipu and Zaki, MAH S and Ranish, Jeffrey A and Miyakawa, Tsuyoshi and Luo, Liqun and Malenka, Robert C and Crabtree, Gerald R and Gleeson, Joseph G} } @article {956, title = {Recurrent homozygous damaging mutation in , encoding a protein disulfide isomerase, in four families with microlissencephaly.}, journal = {J Med Genet}, volume = {57}, year = {2020}, month = {2020 04}, pages = {274-282}, abstract = {

BACKGROUND: Protein disulfide isomerase (PDI) proteins are part of the thioredoxin protein superfamily. PDIs are involved in the formation and rearrangement of disulfide bonds between cysteine residues during protein folding in the endoplasmic reticulum and are implicated in stress response pathways.

METHODS: Eight children from four consanguineous families residing in distinct geographies within the Middle East and Central Asia were recruited for study. All probands showed structurally similar microcephaly with lissencephaly (microlissencephaly) brain malformations. DNA samples from each family underwent whole exome sequencing, assessment for repeat expansions and confirmatory segregation analysis.

RESULTS: An identical homozygous variant in (c.500G>A), encoding thioredoxin-related transmembrane protein 2, segregated with disease in all four families. This variant changed the last coding base of exon 6, and impacted mRNA stability. All patients presented with microlissencephaly, global developmental delay, intellectual disability and epilepsy. While is an activator of cellular repeat expansion toxicity, patients showed no evidence of repeat expansions.

CONCLUSION: The c.500G>A allele associates with recessive microlissencephaly, and patients show no evidence of expansions. is the first PDI implicated in a recessive disease, suggesting a protein isomerisation defect in microlissencephaly.

}, keywords = {Amino Acid Sequence, Child, Child, Preschool, Consanguinity, Endoplasmic Reticulum, Exons, Female, Genetic Predisposition to Disease, Homozygote, Humans, Male, Membrane Proteins, Microcephaly, Mutation, Protein Disulfide-Isomerases, Protein Folding, Thioredoxins, Whole Exome Sequencing}, issn = {1468-6244}, doi = {10.1136/jmedgenet-2019-106409}, author = {Ghosh, Shereen Georges and Wang, Lu and Breuss, Martin W and Green, Joshua D and Stanley, Valentina and Yang, Xiaoxu and Ross, Danica and Traynor, Bryan J and Alhashem, Amal M and Azam, Matloob and Selim, Laila and Bastaki, Laila and Elbastawisy, Hanan I and Temtamy, Samia and Zaki, MAH and Gleeson, Joseph G} } @article {525, title = {MendelProb: probability and sample size calculations for Mendelian studies of exome and whole genome sequence data.}, journal = {Bioinformatics}, volume = {35}, year = {2019}, month = {2019 02 01}, pages = {529-531}, abstract = {

Motivation: For the design of genetic studies, it is necessary to perform power calculations. Although for Mendelian traits the power of detecting linkage for pedigree(s) can be determined, it is also of great interest to determine the probability of identifying multiple pedigrees or unrelated cases with variants in the same gene. For many diseases, due to extreme locus heterogeneity this probability can be small. If only one family is observed segregating a variant classified as likely pathogenic or of unknown significance, the gene cannot be implicated in disease etiology. The probability of identifying several disease families or cases is dependent on the gene-specific disease prevalence and the sample size. The observation of multiple disease families or cases with variants in the same gene as well as evidence of pathogenicity from other sources, e.g. in silico prediction, expression and functional studies, can aid in implicating a gene in disease etiology. MendelProb can determine the probability of detecting a minimum number of families or cases with variants in the same gene. It can also calculate the probability of detecting genes with variants in different data types, e.g. identifying a variant in at least one family that can establish linkage and more the two additional families regardless of their size. Additionally, for a specified probability MendelProb can determine the number of probands which need to be screened to detect a minimum number of individuals with variants within the same gene.

Results: A single Mendelian disease family is not sufficient to implicate a gene in disease etiology. It is necessary to observe multiple families or cases with potentially pathogenic variants in the same gene. MendelProb, an R library, was developed to determine the probability of observing multiple families and cases with variants within a gene and to also establish the numbers of probands to screen to detect multiple observations of variants within a gene.

Availability and implementation: https://github.com/statgenetics/mendelprob.

}, keywords = {Exome, Genetic Linkage, Genomics, Humans, Pedigree, Probability, Sample Size, Software}, issn = {1367-4811}, doi = {10.1093/bioinformatics/bty542}, author = {He, Zongxiao and Wang, Lu and DeWan, Andrew T and Leal, Suzanne M} }