@article {779, title = {Bi-allelic ADARB1 Variants Associated with Microcephaly, Intellectual Disability, and Seizures.}, journal = {Am J Hum Genet}, volume = {106}, year = {2020}, month = {2020 04 02}, pages = {467-483}, abstract = {

The RNA editing enzyme ADAR2 is essential for the recoding of brain transcripts. Impaired ADAR2 editing leads to early-onset epilepsy and premature death in a mouse model. Here, we report bi-allelic variants in ADARB1, the gene encoding ADAR2, in four unrelated individuals with microcephaly, intellectual disability, and epilepsy. In one individual, a homozygous variant in one of the double-stranded RNA-binding domains (dsRBDs) was identified. In the others, variants were situated in or around the deaminase domain. To evaluate the effects of these variants on ADAR2 enzymatic activity, we performed in~vitro assays with recombinant proteins in HEK293T cells and ex~vivo assays with fibroblasts derived from one of the individuals. We demonstrate that these ADAR2 variants lead to reduced editing activity on a known ADAR2 substrate. We also demonstrate that one variant leads to changes in splicing of ADARB1 transcript isoforms. These findings reinforce the importance of RNA editing in brain development and introduce ADARB1 as a genetic etiology in individuals with intellectual disability, microcephaly, and epilepsy.

}, keywords = {Adenosine Deaminase, Alleles, Alternative Splicing, Child, Child, Preschool, Genetic Predisposition to Disease, Genetic Variation, HEK293 Cells, Humans, Intellectual Disability, Male, Microcephaly, RNA Splicing, RNA-Binding Proteins, Seizures}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2020.02.015}, author = {Tan, Tiong Yang and Sedm{\'\i}k, Ji{\v r}{\'\i} and Fitzgerald, Mark P and Halevy, Rivka Sukenik and Keegan, Liam P and Helbig, Ingo and Basel-Salmon, Lina and Cohen, Lior and Straussberg, Rachel and Chung, Wendy K and Helal, Mayada and Maroofian, Reza and Houlden, Henry and Juusola, Jane and Sadedin, Simon and Pais, Lynn and Howell, Katherine B and White, Susan M and Christodoulou, John and O{\textquoteright}Connell, Mary A} } @article {432, title = {Nemaline myopathy and distal arthrogryposis associated with an autosomal recessive~TNNT3~splice variant.}, journal = {Hum Mutat}, volume = {39}, year = {2018}, month = {2018 03}, pages = {383-388}, abstract = {

A male neonate presented with severe weakness, hypotonia, contractures and congenital scoliosis. Skeletal muscle specimens showed marked atrophy and degeneration of fast fibers with striking nemaline rods and hypertrophy of slow fibers that were ultrastructurally normal. A neuromuscular gene panel identified a homozygous essential splice variant in TNNT3 (chr11:1956150G~>~A, NM_006757.3:c.681+1G~>~A). TNNT3 encodes skeletal troponin-T and is associated with autosomal dominant distal arthrogryposis. TNNT3 has not previously been associated with nemaline myopathy (NM), a rare congenital myopathy linked to defects in proteins associated with thin filament structure and regulation. cDNA studies confirmed pathogenic consequences of the splice variant, eliciting exon-skipping and intron retention events leading to a frameshift. Western blot showed deficiency of troponin-T protein with secondary loss of troponin-I . We establish a homozygous splice variant in TNNT3 as the likely cause of severe congenital NM with distal arthrogryposis, characterized by specific involvement of Type-2 fibers and deficiency of troponin-T .

}, keywords = {Arthrogryposis, Genes, Recessive, Humans, Infant, Infant, Newborn, Male, Myopathies, Nemaline, RNA Splice Sites, RNA Splicing, RNA, Messenger, Troponin T}, issn = {1098-1004}, doi = {10.1002/humu.23385}, author = {Sandaradura, Sarah A and Bournazos, Adam and Mallawaarachchi, Amali and Cummings, Beryl B and Waddell, Leigh B and Jones, Kristi J and Troedson, Christopher and Sudarsanam, Annapurna and Nash, Benjamin M and Peters, Gregory B and Algar, Elizabeth M and MacArthur, Daniel G and North, Kathryn N and Brammah, Susan and Charlton, Amanda and Laing, Nigel G and Wilson, Meredith J and Davis, Mark R and Cooper, Sandra T} } @article {395, title = {Mutations in KDSR Cause Recessive Progressive Symmetric Erythrokeratoderma.}, journal = {Am J Hum Genet}, volume = {100}, year = {2017}, month = {2017 Jun 01}, pages = {978-984}, abstract = {

The discovery of new genetic determinants of inherited skin disorders has been instrumental to the understanding of epidermal function, differentiation, and renewal. Here, we show that mutations in KDSR (3-ketodihydrosphingosine reductase), encoding an enzyme in the ceramide synthesis pathway, lead to a previously undescribed recessive Mendelian disorder in the progressive symmetric erythrokeratoderma spectrum. This disorder is characterized by severe lesions of thick scaly skin on the face and genitals and thickened, red, and scaly skin on the hands and feet. Although exome sequencing revealed several of the KDSR mutations, we employed genome sequencing to discover a pathogenic 346 kb inversion in multiple probands, and cDNA sequencing and a splicing assay established that two mutations, including a recurrent silent third base change, cause exon skipping. Immunohistochemistry and yeast complementation studies demonstrated that the mutations cause defects in KDSR function. Systemic isotretinoin therapy has achieved nearly complete resolution in the two probands in whom it has been applied, consistent with the effects of retinoic acid on alternative pathways for ceramide generation.

}, keywords = {Alcohol Oxidoreductases, Ceramides, Genes, Recessive, Genetic Complementation Test, Genetic Predisposition to Disease, Heterozygote, Humans, Intermediate Filament Proteins, Keratosis, Mutation, Polymorphism, Single Nucleotide, RNA Splicing, Saccharomyces cerevisiae}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.05.003}, author = {Boyden, Lynn M and Vincent, Nicholas G and Zhou, Jing and Hu, Ronghua and Craiglow, Brittany G and Bayliss, Susan J and Rosman, Ilana S and Lucky, Anne W and Diaz, Luis A and Goldsmith, Lowell A and Paller, Amy S and Lifton, Richard P and Baserga, Susan J and Choate, Keith A} } @article {24, title = {Bi-allelic Mutations in PKD1L1 Are Associated with Laterality Defects in Humans.}, journal = {Am J Hum Genet}, volume = {99}, year = {2016}, month = {2016 Oct 06}, pages = {886-893}, abstract = {

Disruption of the establishment of left-right (L-R) asymmetry leads to situs anomalies ranging from situs inversus totalis (SIT) to situs ambiguus (heterotaxy). The genetic causes of laterality defects in humans are highly heterogeneous. Via whole-exome sequencing (WES), we identified homozygous mutations in PKD1L1 from three affected individuals in two unrelated families. PKD1L1 encodes a polycystin-1-like protein and its loss of function is known to cause laterality defects in mouse and medaka fish models. Family 1 had one fetus and one deceased child with heterotaxy and complex congenital heart malformations. WES identified a homozygous splicing mutation, c.6473+2_6473+3delTG, which disrupts the invariant splice donor site in intron 42, in both affected individuals. In the second family, a homozygous c.5072G>C (p.Cys1691Ser) missense mutation was detected in an individual with SIT and congenital heart disease. The p.Cys1691Ser substitution affects a highly conserved cysteine residue and is predicted by molecular modeling to disrupt a disulfide bridge essential for the proper folding of the G protein-coupled receptor proteolytic site (GPS) motif. Damaging effects associated with substitutions of this conserved cysteine residue in the GPS motif have also been reported in other genes, namely GPR56, BAI3, and PKD1 in human and lat-1 in C.~elegans, further supporting the likely pathogenicity of p.Cys1691Ser in PKD1L1. The identification of bi-allelic PKD1L1 mutations recapitulates previous findings regarding phenotypic consequences of loss of function of the orthologous genes in mice and medaka fish and further expands our understanding of genetic contributions to laterality defects in humans.

}, keywords = {Alleles, Amino Acid Motifs, Amino Acid Sequence, Animals, Caenorhabditis elegans, Cysteine, Exome, Female, Fetal Diseases, Functional Laterality, Heart Defects, Congenital, Heterotaxy Syndrome, Homozygote, Humans, Infant, Newborn, Introns, Male, Membrane Proteins, Mice, Middle Aged, Models, Molecular, Mutation, Mutation, Missense, Oryzias, Pedigree, RNA Splicing, Situs Inversus}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2016.07.011}, author = {Vetrini, Francesco and D{\textquoteright}Alessandro, Lisa C A and Akdemir, Zeynep C and Braxton, Alicia and Azamian, Mahshid S and Eldomery, Mohammad K and Miller, Kathryn and Kois, Chelsea and Sack, Virginia and Shur, Natasha and Rijhsinghani, Asha and Chandarana, Jignesh and Ding, Yan and Holtzman, Judy and Jhangiani, Shalini N and Muzny, Donna M and Gibbs, Richard A and Eng, Christine M and Hanchard, Neil A and Harel, Tamar and Rosenfeld, Jill A and Belmont, John W and Lupski, James R and Yang, Yaping} } @article {103, title = {Chimeric transcripts resulting from complex duplications in chromosome Xq28.}, journal = {Hum Genet}, volume = {135}, year = {2016}, month = {2016 Feb}, pages = {253-6}, abstract = {

Gene fusions have been observed in somatic alterations in cancer and in schizophrenia. However, the underlying mechanism(s) for their formation are poorly understood. We experimentally demonstrated the expression of splicing variants of in silico predicted chimeric genes F8/CSAG1 and BCAP31/TEX28 in two individuals with de novo complex genomic rearrangements of Xq28; F8/CSAG1 includes exonization of an ERVL-MaLR intronic repetitive element. We provide evidence that replicative repair may contribute to exon shuffling processes and diversify the repertoire of expressed transcripts.

}, keywords = {Antigens, Neoplasm, Base Sequence, Cell Line, Chromosomes, Human, X, Exons, Gene Duplication, Gene Expression Regulation, Gene Rearrangement, Humans, Introns, Male, Membrane Proteins, Molecular Sequence Data, Neoplasm Proteins, RNA Splicing, RNA, Messenger, Transcription, Genetic}, issn = {1432-1203}, doi = {10.1007/s00439-015-1614-x}, author = {Zuccherato, Luciana W and Alleva, Benjamin and Whiters, Marjorie A and Carvalho, Claudia M B and Lupski, James R} } @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} } @article {83, title = {Mitral regurgitation as a phenotypic manifestation of nonphotosensitive trichothiodystrophy due to a splice variant in MPLKIP.}, journal = {BMC Med Genet}, volume = {17}, year = {2016}, month = {2016 Feb 16}, pages = {13}, abstract = {

BACKGROUND: Nonphotosensitive trichothiodystrophy (TTDN) is a rare autosomal recessive disorder of neuroectodermal origin. The condition is marked by hair abnormalities, intellectual impairment, nail dystrophies and susceptibility to infections but with no UV sensitivity.

METHODS: We identified three consanguineous Pakistani families with varied TTDN features and used homozygosity mapping, linkage analysis, and Sanger and exome sequencing in order to identify pathogenic variants. Haplotype analysis was performed and haplotype age estimated. A splicing assay was used to validate the effect of the MPLKIP splice variant on expression.

RESULTS: Affected individuals from all families exhibit several TTDN features along with a heart-specific feature, i.e. mitral regurgitation. Exome sequencing in the probands from families ED168 and ED241 identified a homozygous splice mutation c.339 + 1G > A within MPLKIP. The same splice variant co-segregates with TTDN in a third family ED210. The MPLKIP splice variant was not found in public databases, e.g. the Exome Aggregation Consortium, and in unrelated Pakistani controls. Functional analysis of the splice variant confirmed intron retention, which leads to protein truncation and loss of a phosphorylation site. Haplotype analysis identified a 585.1-kb haplotype which includes the MPLKIP variant, supporting the existence of a founder haplotype that is estimated to be 25,900 years old.

CONCLUSION: This study extends the allelic and phenotypic spectra of MPLKIP-related TTDN, to include a splice variant that causes cardiomyopathy as part of the TTDN phenotype.

}, keywords = {Adaptor Proteins, Signal Transducing, Adolescent, Adult, Alleles, Asian Continental Ancestry Group, Child, Cloning, Molecular, Exome, Female, Genetic Linkage, Haplotypes, HEK293 Cells, Homozygote, Humans, Introns, Male, Mitral Valve Insufficiency, Pakistan, Pedigree, Phenotype, Polymorphism, Single Nucleotide, RNA Splicing, Sequence Analysis, DNA, Trichothiodystrophy Syndromes, Young Adult}, issn = {1471-2350}, doi = {10.1186/s12881-016-0275-5}, author = {Shah, Khadim and Ali, Raja Hussain and Ansar, Muhammad and Lee, Kwanghyuk and Chishti, Muhammad Salman and Abbe, Izoduwa and Li, Biao and Smith, Joshua D and Nickerson, Deborah A and Shendure, Jay and Coucke, Paul J and Steyaert, Wouter and Bamshad, Michael J and Santos-Cortez, Regie Lyn P and Leal, Suzanne M and Ahmad, Wasim} } @article {108, title = {De Novo GMNN Mutations Cause Autosomal-Dominant Primordial Dwarfism Associated with Meier-Gorlin Syndrome.}, journal = {Am J Hum Genet}, volume = {97}, year = {2015}, month = {2015 Dec 03}, pages = {904-13}, abstract = {

Meier-Gorlin syndrome (MGS) is a genetically heterogeneous primordial dwarfism syndrome known to be caused by biallelic loss-of-function mutations in one of five genes encoding pre-replication complex proteins: ORC1, ORC4, ORC6, CDT1, and CDC6. Mutations in these genes cause disruption of the origin of DNA replication initiation. To date, only an autosomal-recessive inheritance pattern has been described in individuals with this disorder, with a molecular etiology established in about three-fourths of cases. Here, we report three subjects with MGS and de novo heterozygous mutations in the 5{\textquoteright} end of GMNN, encoding the DNA replication inhibitor geminin. We identified two truncating mutations in exon 2 (the 1(st) coding exon), c.16A>T (p.Lys6(*)) and c.35_38delTCAA (p.Ile12Lysfs(*)4), and one missense mutation, c.50A>G (p.Lys17Arg), affecting the second-to-last nucleotide of exon 2 and possibly RNA splicing. Geminin is present during the S, G2, and M phases of the cell cycle and is degraded during the metaphase-anaphase transition by the anaphase-promoting complex (APC), which recognizes the destruction box sequence near the 5{\textquoteright} end of the geminin protein. All three GMNN mutations identified alter sites 5{\textquoteright} to residue Met28 of the protein, which is located within the destruction box. We present data supporting a gain-of-function mechanism, in which the GMNN mutations result in proteins lacking the destruction box and hence increased protein stability and prolonged inhibition of replication leading to autosomal-dominant MGS.

}, keywords = {Adolescent, Amino Acid Sequence, Base Sequence, Cell Cycle, Child, Preschool, Congenital Microtia, Dwarfism, Exons, Female, Geminin, Gene Expression, Genes, Dominant, Growth Disorders, Heterozygote, High-Throughput Nucleotide Sequencing, Humans, Inheritance Patterns, Male, Micrognathism, Molecular Sequence Data, Mutation, Patella, Pedigree, Protein Stability, Proteolysis, RNA Splicing, Sequence Alignment}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2015.11.006}, author = {Burrage, Lindsay C and Charng, Wu-Lin and Eldomery, Mohammad K and Willer, Jason R and Davis, Erica E and Lugtenberg, Dorien and Zhu, Wenmiao and Leduc, Magalie S and Akdemir, Zeynep C and Azamian, Mahshid and Zapata, Gladys and Hernandez, Patricia P and Schoots, Jeroen and de Munnik, Sonja A and Roepman, Ronald and Pearring, Jillian N and Jhangiani, Shalini and Katsanis, Nicholas and Vissers, Lisenka E L M and Brunner, Han G and Beaudet, Arthur L and Rosenfeld, Jill A and Muzny, Donna M and Gibbs, Richard A and Eng, Christine M and Xia, Fan and Lalani, Seema R and Lupski, James R and Bongers, Ernie M H F and Yang, Yaping} } @article {252, title = {CLP1 founder mutation links tRNA splicing and maturation to cerebellar development and neurodegeneration.}, journal = {Cell}, volume = {157}, year = {2014}, month = {2014 Apr 24}, pages = {651-63}, abstract = {

Neurodegenerative diseases can occur so early as to affect neurodevelopment. From a cohort of more than 2,000 consanguineous families with childhood neurological disease, we identified a founder mutation in four independent pedigrees in cleavage and polyadenylation factor I subunit 1 (CLP1). CLP1 is a multifunctional kinase implicated in tRNA, mRNA, and siRNA maturation. Kinase activity of the CLP1 mutant protein was defective, and the tRNA endonuclease complex (TSEN) was destabilized, resulting in impaired pre-tRNA cleavage. Germline clp1 null zebrafish showed cerebellar neurodegeneration that was rescued by wild-type, but not mutant, human CLP1 expression. Patient-derived induced neurons displayed both depletion of mature tRNAs and accumulation of unspliced pre-tRNAs. Transfection of partially processed tRNA fragments into patient cells exacerbated an oxidative stress-induced reduction in cell survival. Our data link tRNA maturation to neuronal development and neurodegeneration through defective CLP1 function in humans.

}, keywords = {Animals, Brain, Cerebellum, Cleavage And Polyadenylation Specificity Factor, Female, Humans, Male, Mice, Models, Molecular, Neurodegenerative Diseases, Nuclear Proteins, Pedigree, Phosphotransferases, RNA Splicing, RNA, Transfer, Saccharomyces cerevisiae, Transcription Factors, Zebrafish, Zebrafish Proteins}, issn = {1097-4172}, doi = {10.1016/j.cell.2014.03.049}, author = {Schaffer, Ashleigh E and Eggens, Veerle R C and {\c C}a{\u g}layan, Ahmet Okay and Reuter, Miriam S and Scott, Eric and Coufal, Nicole G and Silhavy, Jennifer L and Xue, Yuanchao and Kayserili, H{\"u}lya and Yasuno, Katsuhito and Rosti, Rasim Ozgur and Abdellateef, Mostafa and Caglar, Caner and Kasher, Paul R and Cazemier, J Leonie and Weterman, Marian A and Cantagrel, Vincent and Cai, Na and Zweier, Christiane and Altunoglu, Umut and Satkin, N Bilge and Aktar, Fesih and Tuysuz, Beyhan and Yalcinkaya, Cengiz and Caksen, Huseyin and Bilguvar, Kaya and Fu, Xiang-Dong and Trotta, Christopher R and Gabriel, Stacey and Reis, Andr{\'e} and G{\"u}nel, Murat and Baas, Frank and Gleeson, Joseph G} }