Medicine and Health Sciences Commons^™

Deficient Histone H3 Propionylation By Brpf1-Kat6 Complexes In Neurodevelopmental Disorders And Cancer., Kezhi Yan, Justine Rousseau, Keren Machol, Laura A. Cross, Katherine E. Agre, Cynthia Forster Gibson, Anne Goverde, Kendra Engleman, Hannah Verdin, Elfride De Baere, Lorraine Potocki, Dihong Zhou, Maxime Cadieux-Dion, Gary A. Bellus, Monisa D. Wagner, Rebecca J. Hale, Natacha Esber, Alan F. Riley, Benjamin D. Solomon, Megan T. Cho, Kirsty Mcwalter, Roy Eyal, Meagan K. Hainlen, Bryce A. Mendelsohn, Hillary M. Porter, Brendan C. Lanpher, Andrea M. Lewis, Juliann Savatt, Isabelle Thiffault, Bert Callewaert, Philippe M. Campeau, Xiang-Jiao Yang

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Lysine acetyltransferase 6A (KAT6A) and its paralog KAT6B form stoichiometric complexes with bromodomain- and PHD finger-containing protein 1 (BRPF1) for acetylation of histone H3 at lysine 23 (H3K23). We report that these complexes also catalyze H3K23 propionylation in vitro and in vivo. Immunofluorescence microscopy and ATAC-See revealed the association of this modification with active chromatin. Brpf1 deletion obliterates the acylation in mouse embryos and fibroblasts. Moreover, we identify BRPF1 variants in 12 previously unidentified cases of syndromic intellectual disability and demonstrate that these cases and known BRPF1 variants impair H3K23 propionylation. Cardiac anomalies are present in a subset of the …

H3k27m Induces Defective Chromatin Spread Of Prc2-Mediated Repressive H3k27me2/Me3 And Is Essential For Glioma Tumorigenesis., Ashot S. Harutyunyan, Brian Krug, Haifen Chen, Simon Papillon-Cavanagh, Michele Zeinieh, Nicolas De Jay, Shriya Deshmukh, Carol C L Chen, Jad Belle, Leonie G. Mikael, Dylan M. Marchione, Rui Li, Hamid Nikbakht, Bo Hu, Gael Cagnone, Warren A. Cheung, Abdulshakour Mohammadnia, Denise Bechet, Damien Faury, Melissa K. Mcconechy, Manav Pathania, Siddhant U. Jain, Benjamin Ellezam, Alexander G. Weil, Alexandre Montpetit, Paolo Salomoni, Tomi Pastinen, Chao Lu, Peter W. Lewis, Benjamin A. Garcia, Claudia L. Kleinman, Nada Jabado, Jacek Majewski

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Lys-27-Met mutations in histone 3 genes (H3K27M) characterize a subgroup of deadly gliomas and decrease genome-wide H3K27 trimethylation. Here we use primary H3K27M tumor lines and isogenic CRISPR-edited controls to assess H3K27M effects in vitro and in vivo. We find that whereas H3K27me3 and H3K27me2 are normally deposited by PRC2 across broad regions, their deposition is severely reduced in H3.3K27M cells. H3K27me3 is unable to spread from large unmethylated CpG islands, while H3K27me2 can be deposited outside these PRC2 high-affinity sites but to levels corresponding to H3K27me3 deposition in wild-type cells. Our findings indicate that PRC2 recruitment and propagation on …

Precision Medicine In Pediatric Cancer: Current Applications And Future Prospects., Atif Ahmed, Divya S. Vundamati, Midhat S. Farooqi, Erin M. Guest

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Precision oncologic medicine is an emerging approach for cancer treatment that has recently taken giant steps in solid clinical practice. Recent advances in molecular diagnostics that can analyze the individual tumor's variability in genes have provided greater understanding and additional strategies to treat cancers. Although tumors can be tested by several molecular methods, the use of next-generation sequencing (NGS) has greatly facilitated our understanding of pediatric cancer and identified additional therapeutic opportunities. Pediatric tumors have a different genetic make-up, with a fewer number of actionable targets than adult tumors. Nevertheless, precision oncology in the pediatric population has greatly improved the …

Hypotonia And Intellectual Disability Without Dysmorphic Features In A Patient With Pign-Related Disease., Isabelle Thiffault, Britton Zuccarelli, Holly Welsh, Xuan Yuan, Emily Farrow, Lee Zellmer, Neil Miller, Sarah Soden, Ahmed Abdelmoity, Robert A Brodsky, Carol Saunders

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BACKGROUND: Defects in the human glycosylphosphatidylinositol anchor biosynthetic pathway are associated with inherited glycosylphosphatidylinositol (GPI)-deficiencies characterized by a broad range of clinical phenotypes including multiple congenital anomalies, dysmorphic faces, developmental delay, hypotonia, and epilepsy. Biallelic variants in PIGN, encoding phosphatidylinositol-glycan biosynthesis class N have been recently associated with multiple congenital anomalies hypotonia seizure syndrome.

CASE PRESENTATION: Our patient is a 2 year old male with hypotonia, global developmental delay, and focal epilepsy. Trio whole-exome sequencing revealed heterozygous variants in PIGN, c.181G > T (p.Glu61*) and c.284G > A (p.Arg95Gln). Analysis of FLAER and anti-CD59 by flow-cytometry demonstrated a shift in this patient's …

Exome Analysis Of Rare And Common Variants Within The Nod Signaling Pathway., Gaia Andreoletti, Valentina Shakhnovich, Kathy Christenson, Tracy Coelho, Rachel Haggarty, Nadeem A. Afzal, Akshay Batra, Britt-Sabina Petersen, Matthew Mort, R Mark Beattie, Sarah Ennis

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Pediatric inflammatory bowel disease (pIBD) is a chronic heterogeneous disorder. This study looks at the burden of common and rare coding mutations within 41 genes comprising the NOD signaling pathway in pIBD patients. 136 pIBD and 106 control samples underwent whole-exome sequencing. We compared the burden of common, rare and private mutation between these two groups using the SKAT-O test. An independent replication cohort of 33 cases and 111 controls was used to validate significant findings. We observed variation in 40 of 41 genes comprising the NOD signaling pathway. Four genes were significantly associated with disease in the discovery cohort …

A Novel Compound-Heterozygous Epithelial Cell Adhesion Molecule Mutation In Tufting Enteropathy., Valentina Shakhnovich, Darrell Dinwiddie, Amber Hildreth, Thomas M. Attard, Stephen Kingsmore

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No abstract provided.

Biallelic Mutations In Tbcd, Encoding The Tubulin Folding Cofactor D, Perturb Microtubule Dynamics And Cause Early-Onset Encephalopathy., Elisabetta Flex, Marcello Niceta, Serena Cecchetti, Isabelle Thiffault, Margaret G. Au, Alessandro Capuano, Emanuela Piermarini, Anna A. Ivanova, Joshua W. Francis, Giovanni Chillemi, Balasubramanian Chandramouli, Giovanna Carpentieri, Charlotte A. Haaxma, Andrea Ciolfi, Simone Pizzi, Ganka V. Douglas, Kara Levine, Antonella Sferra, Maria Lisa Dentici, Rolph R. Pfundt, Jean-Baptist Lepichon, Emily G. Farrow, Frank Baas, Fiorella Piemonte, Bruno Dallapiccola, John M. Graham, Carol J. Saunders, Enrico Bertini, Richard A. Kahn, David A. Koolen, Marco Tartaglia

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Microtubules are dynamic cytoskeletal elements coordinating and supporting a variety of neuronal processes, including cell division, migration, polarity, intracellular trafficking, and signal transduction. Mutations in genes encoding tubulins and microtubule-associated proteins are known to cause neurodevelopmental and neurodegenerative disorders. Growing evidence suggests that altered microtubule dynamics may also underlie or contribute to neurodevelopmental disorders and neurodegeneration. We report that biallelic mutations in TBCD, encoding one of the five co-chaperones required for assembly and disassembly of the αβ-tubulin heterodimer, the structural unit of microtubules, cause a disease with neurodevelopmental and neurodegenerative features characterized by early-onset cortical atrophy, secondary hypomyelination, microcephaly, thin …

Recessive Mutations In Polr1c Cause A Leukodystrophy By Impairing Biogenesis Of Rna Polymerase Iii., Isabelle Thiffault, Nicole I Wolf, Diane Forget, Kether Guerrero, Luan T. Tran, Karine Choquet, Mathieu Lavallée-Adam, Christian Poitras, Bernard Brais, Grace Yoon, Laszlo Sztriha, Richard I. Webster, Dagmar Timmann, Bart P. Van De Warrenburg, Jürgen Seeger, Alíz Zimmermann, Adrienn Máté, Cyril Goizet, Eva Fung, Marjo S. Van Der Knaap, Sébastien Fribourg, Adeline Vanderver, Cas Simons, Ryan J. Taft, John R. Yates, Benoit Coulombe, Geneviève Bernard

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A small proportion of 4H (Hypomyelination, Hypodontia and Hypogonadotropic Hypogonadism) or RNA polymerase III (POLR3)-related leukodystrophy cases are negative for mutations in the previously identified causative genes POLR3A and POLR3B. Here we report eight of these cases carrying recessive mutations in POLR1C, a gene encoding a shared POLR1 and POLR3 subunit, also mutated in some Treacher Collins syndrome (TCS) cases. Using shotgun proteomics and ChIP sequencing, we demonstrate that leukodystrophy-causative mutations, but not TCS mutations, in POLR1C impair assembly and nuclear import of POLR3, but not POLR1, leading to decreased binding to POLR3 target genes. This study is the first …

A Patient With Polymerase E1 Deficiency (Pole1): Clinical Features And Overlap With Dna Breakage/Instability Syndromes., Isabelle Thiffault, Carol Saunders, Janda Jenkins, Nikita Raje, Kristi Canty, Mukta Sharma, Lauren Grote, Holly I. Welsh, Emily Farrow, Greyson Twist, Neil Miller, David Zwick, Lee Zellmer, Stephen F. Kingsmore, Nicole P. Safina

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BACKGROUND: Chromosome instability syndromes are a group of inherited conditions associated with chromosomal instability and breakage, often leading to immunodeficiency, growth retardation and increased risk of malignancy.

CASE PRESENTATION: We performed exome sequencing on a girl with a suspected chromosome instability syndrome that manifested as growth retardation, microcephaly, developmental delay, dysmorphic features, poikiloderma, immune deficiency with pancytopenia, and myelodysplasia. She was homozygous for a previously reported splice variant, c.4444 + 3A > G in the POLE1 gene, which encodes the catalytic subunit of DNA polymerase E.

CONCLUSION: This is the second family with POLE1-deficency, with the affected individual demonstrating a more …

Novel Napi-Iic Mutations Causing Hhrh And Idiopathic Hypercalciuria In Several Unrelated Families: Long-Term Follow-Up In One Kindred., Y Yu, S R. Sanderson, M Reyes, A Sharma, N Dunbar, Tarak Srivastava, H Jüppner, C Bergwitz

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Homozygous and compound heterozygous mutations in SLC34A3, the gene encoding the sodium-dependent co-transporter NaPi-IIc, cause hereditary hypophosphatemic rickets with hypercalciuria (HHRH), a disorder characterized by renal phosphate-wasting resulting in hypophosphatemia, elevated 1,25(OH)(2) vitamin D levels, hypercalciuria, rickets/osteomalacia, and frequently kidney stones or nephrocalcinosis. Similar albeit less severe biochemical changes are also observed in heterozygous carriers, which are furthermore indistinguishable from those encountered in idiopathic hypercalciuria (IH). We now searched for SLC34A3 mutations (exons and introns) in two previously not reported HHRH kindreds, which resulted in the identification of three novel mutations. The affected members of kindred A were compound heterozygous …