@article {543, title = {Functional Dysregulation of CDC42 Causes Diverse Developmental Phenotypes.}, journal = {Am J Hum Genet}, volume = {102}, year = {2018}, month = {2018 Feb 01}, pages = {309-320}, abstract = {

Exome sequencing has markedly enhanced the discovery of genes implicated in Mendelian disorders, particularly for individuals in whom a known clinical entity could not be assigned. This has led to the recognition that phenotypic heterogeneity resulting from allelic mutations occurs more commonly than previously appreciated. Here, we report that missense variants in CDC42, a gene encoding a small GTPase functioning as an intracellular signaling node, underlie a clinically heterogeneous group of phenotypes characterized by variable growth dysregulation, facial dysmorphism, and neurodevelopmental, immunological, and hematological anomalies, including a phenotype resembling Noonan syndrome, a developmental disorder caused by dysregulated RAS signaling. In silico, in~vitro, and in~vivo analyses demonstrate that mutations variably perturb CDC42 function by altering the switch between the active and inactive states of the GTPase and/or affecting CDC42 interaction with effectors, and differentially disturb cellular and developmental processes. These findings reveal the remarkably variable impact that dominantly acting CDC42 mutations have on cell function and development, creating challenges in syndrome definition, and exemplify the importance of functional profiling for syndrome recognition and delineation.

}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.12.015}, author = {Martinelli, Simone and Krumbach, Oliver H F and Pantaleoni, Francesca and Coppola, Simona and Amin, Ehsan and Pannone, Luca and Nouri, Kazem and Farina, Luciapia and Dvorsky, Radovan and Lepri, Francesca and Buchholzer, Marcel and Konopatzki, Raphael and Walsh, Laurence and Payne, Katelyn and Pierpont, Mary Ella and Vergano, Samantha Schrier and Langley, Katherine G and Larsen, Douglas and Farwell, Kelly D and Tang, Sha and Mroske, Cameron and Gallotta, Ivan and Di Schiavi, Elia and Della Monica, Matteo and Lugli, Licia and Rossi, Cesare and Seri, Marco and Cocchi, Guido and Henderson, Lindsay and Baskin, Berivan and Alders, Marielle and Mendoza-Londono, Roberto and Dupuis, Lucie and Nickerson, Deborah A and Chong, Jessica X and Meeks, Naomi and Brown, Kathleen and Causey, Tahnee and Cho, Megan T and Demuth, Stephanie and Digilio, Maria Cristina and Gelb, Bruce D and Bamshad, Michael J and Zenker, Martin and Ahmadian, Mohammad Reza and Hennekam, Raoul C and Tartaglia, Marco and Mirzaa, Ghayda M} } @article {388, title = {Heterozygous De Novo UBTF Gain-of-Function Variant Is Associated with Neurodegeneration in Childhood.}, journal = {Am J Hum Genet}, volume = {101}, year = {2017}, month = {2017 Aug 03}, pages = {267-273}, abstract = {

Ribosomal RNA (rRNA) is transcribed from rDNA by RNA polymerase I (Pol I) to produce the 45S precursor of the 28S, 5.8S, and 18S rRNA components of the ribosome. Two transcription factors have been defined for Pol I in mammals, the selectivity factor SL1, and the upstream binding transcription factor (UBF), which interacts with the upstream control element to facilitate the assembly of the transcription initiation complex including SL1 and Pol I. In seven unrelated affected individuals, all suffering from developmental regression starting at 2.5-7 years, we identified a heterozygous variant, c.628G>A in UBTF, encoding p.Glu210Lys in UBF, which occurred de novo in~all cases. While the levels of UBF, Ser388 phosphorylated UBF, and other Pol I-related components (POLR1E, TAF1A, and TAF1C) remained unchanged in cells of an affected individual, the variant conferred gain of function to UBF, manifesting by markedly increased UBF binding to the rDNA promoter and to the 5{\textquoteright}- external transcribed spacer. This was associated with significantly increased 18S expression, and enlarged nucleoli which were reduced in number per cell. The data link neurodegeneration in childhood with altered rDNA chromatin status and rRNA metabolism.

}, keywords = {Adolescent, Adult, Atrophy, Brain, Brain Diseases, Cell Nucleolus, Child, Chromatin, DNA-Binding Proteins, Female, Humans, Male, Neurodegenerative Diseases, Pol1 Transcription Initiation Complex Proteins, Polymorphism, Single Nucleotide, Promoter Regions, Genetic, RNA, Ribosomal, 18S, Young Adult}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.07.002}, author = {Edvardson, Simon and Nicolae, Claudia M and Agrawal, Pankaj B and Mignot, Cyril and Payne, Katelyn and Prasad, Asuri Narayan and Prasad, Chitra and Sadler, Laurie and Nava, Caroline and Mullen, Thomas E and Begtrup, Amber and Baskin, Berivan and Powis, Z{\"o}e and Shaag, Avraham and Keren, Boris and Moldovan, George-Lucian and Elpeleg, Orly} } @article {28, title = {De Novo Mutations in SON Disrupt RNA Splicing of Genes Essential for Brain Development and Metabolism, Causing an Intellectual-Disability Syndrome.}, journal = {Am J Hum Genet}, volume = {99}, year = {2016}, month = {2016 Sep 01}, pages = {711-719}, abstract = {

The overall understanding of the molecular etiologies of intellectual disability (ID) and developmental delay (DD) is increasing as next-generation sequencing technologies identify genetic variants in individuals with such disorders. However, detailed analyses conclusively confirming these variants, as well as the underlying molecular mechanisms explaining the diseases, are often lacking. Here, we report on an ID syndrome caused by de novo heterozygous loss-of-function (LoF) mutations in SON. The syndrome is characterized by ID and/or DD, malformations of the cerebral cortex, epilepsy, vision problems, musculoskeletal abnormalities, and congenital malformations. Knockdown of son in zebrafish resulted in severe malformation of the spine, brain, and eyes. Importantly, analyses of RNA from affected individuals revealed that genes critical for neuronal migration and cortex organization (TUBG1, FLNA, PNKP, WDR62, PSMD3, and~HDAC6) and metabolism (PCK2, PFKL, IDH2, ACY1, and ADA) are significantly downregulated because of the accumulation of mis-spliced transcripts resulting from erroneous SON-mediated RNA splicing. Our data highlight SON as a master regulator governing neurodevelopment and demonstrate the importance of SON-mediated RNA splicing in human development.

}, keywords = {Animals, Brain, Developmental Disabilities, DNA-Binding Proteins, Eye Abnormalities, Female, Genes, Essential, Haploinsufficiency, Head, Heterozygote, Humans, Intellectual Disability, Male, Metabolic Diseases, Minor Histocompatibility Antigens, Mutation, Pedigree, RNA Splicing, RNA, Messenger, Spine, Syndrome, Zebrafish}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2016.06.029}, author = {Kim, Jung-Hyun and Shinde, Deepali N and Reijnders, Margot R F and Hauser, Natalie S and Belmonte, Rebecca L and Wilson, Gregory R and Bosch, Dani{\"e}lle G M and Bubulya, Paula A and Shashi, Vandana and Petrovski, Slav{\'e} and Stone, Joshua K and Park, Eun Young and Veltman, Joris A and Sinnema, Margje and Stumpel, Connie T R M and Draaisma, Jos M and Nicolai, Joost and Yntema, Helger G and Lindstrom, Kristin and de Vries, Bert B A and Jewett, Tamison and Santoro, Stephanie L and Vogt, Julie and Bachman, Kristine K and Seeley, Andrea H and Krokosky, Alyson and Turner, Clesson and Rohena, Luis and Hempel, Maja and Kort{\"u}m, Fanny and Lessel, Davor and Neu, Axel and Strom, Tim M and Wieczorek, Dagmar and Bramswig, Nuria and Laccone, Franco A and Behunova, Jana and Rehder, Helga and Gordon, Christopher T and Rio, Marl{\`e}ne and Romana, Serge and Tang, Sha and El-Khechen, Dima and Cho, Megan T and McWalter, Kirsty and Douglas, Ganka and Baskin, Berivan and Begtrup, Amber and Funari, Tara and Schoch, Kelly and Stegmann, Alexander P A and Stevens, Servi J C and Zhang, Dong-Er and Traver, David and Yao, Xu and MacArthur, Daniel G and Brunner, Han G and Mancini, Grazia M and Myers, Richard M and Owen, Laurie B and Lim, Ssang-Taek and Stachura, David L and Vissers, Lisenka E L M and Ahn, Eun-Young Erin} }