title: A Novel Kleefstra Syndrome-associated Variant That Affects the Conserved TPLXMotif within the Ankyrin Repeat of EHMT1 Leads to Abnormal Protein Folding.
abstract: Kleefstra syndrome (KS) (Mendelian Inheritance in Man (MIM) no. 610253), also known as 9q34 deletion syndrome, is an autosomal dominant disorder caused by haploinsufficiency of euchromatic histone methyltransferase-1 (EHMT1). The clinical phenotype of KS includes moderate to severe intellectual disability with absent speech, hypotonia, brachycephaly, congenital heart defects, and dysmorphic facial features with hypertelorism, synophrys, macroglossia, protruding tongue, and prognathism. Only a few cases ofde novomissense mutations inEHMT1giving rise to KS have been described. However, someEHMT1variants have been described in individuals presenting with autism spectrum disorder or mild intellectual disability, suggesting that the phenotypic spectrum resulting from EHMT1 alterations may be quite broad. In this report, we describe two unrelated patients with complex medical histories consistent with KS in whom next generation sequencing identified the same novel c.2426C>T (p.P809L) missense variant inEHMT1To examine the functional significance of this novel variant, we performed molecular dynamics simulations of the wild type and p.P809L variant, which predicted that the latter would have a propensity to misfold, leading to abnormal histone mark binding. Recombinant EHMT1 p.P809L was also studied using far UV circular dichroism spectroscopy and intrinsic protein fluorescence. These functional studies confirmed the model-based hypotheses and provided evidence for protein misfolding and aberrant target recognition as the underlying pathogenic mechanism for this novel KS-associated variant. This is the first report to suggest that missense variants in EHMT1 that lead to protein misfolding and disrupted histone mark binding can lead to KS.
authors.affiliation: From the Center for Individualized Medicine and.|the Department of Health Science Research, Mayo Clinic, Jacksonville, Florida 32224.
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Blackburn
authors.affiliation: the Division of Hematology, Departments of Internal Medicine and Biochemistry and Molecular Biology.
authors.forename: Alexander
authors.initials: A
authors.lastname: Tischer
authors.affiliation: the Department of Health Science Research, Division of Biomedical Statistics and Informatics.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Zimmermann
authors.affiliation: the Department of Clinical Genomics.|the Center for Individualized Medicine.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Kemppainen
authors.affiliation: the Department of Pediatrics, Division of Genetics and Metabolic Disorders, Wayne State University School of Medicine, Detroit, Michigan 48201, and.
authors.forename: Sujatha
authors.initials: S
authors.lastname: Sastry
authors.affiliation: the Department of Human Genetics, University of Chicago, Chicago, Illinois 60637.
authors.forename: Amy E
authors.initials: AE
authors.lastname: Knight Johnson
authors.affiliation: the Center for Individualized Medicine.|the Department of Health Science Research.
authors.forename: Margot A
authors.initials: MA
authors.lastname: Cousin
authors.affiliation: the Center for Individualized Medicine.|the Department of Health Science Research.
authors.forename: Nicole J
authors.initials: NJ
authors.lastname: Boczek
authors.affiliation: the Center for Individualized Medicine.
authors.forename: Gavin
authors.initials: G
authors.lastname: Oliver
authors.affiliation: the Department of Pediatrics, Division of Genetics and Metabolic Disorders, Wayne State University School of Medicine, Detroit, Michigan 48201, and.
authors.forename: Vinod K
authors.initials: VK
authors.lastname: Misra
authors.affiliation: the Department of Clinical Genomics.|the Department of Neurology, and.
authors.forename: Ralitza H
authors.initials: RH
authors.lastname: Gavrilova
authors.affiliation: the Laboratory of Epigenetics and Chromatin Dynamics, Epigenomics Translational Program, Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota 55905.
authors.forename: Gwen
authors.initials: G
authors.lastname: Lomberk
authors.affiliation: the Division of Hematology, Departments of Internal Medicine and Biochemistry and Molecular Biology.
authors.forename: Matthew
authors.initials: M
authors.lastname: Auton
authors.affiliation: the Laboratory of Epigenetics and Chromatin Dynamics, Epigenomics Translational Program, Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota 55905, urrutia.raul@mayo.edu.
authors.forename: Raul
authors.initials: R
authors.lastname: Urrutia
authors.affiliation: the Department of Clinical Genomics, klee.eric@mayo.edu.|the Center for Individualized Medicine.|the Department of Health Science Research.
authors.forename: Eric W
authors.initials: EW
authors.lastname: Klee
mesh_terms: D020816:Amino Acid Motifs; D017089:Ankyrin Repeat; D000067877:Autism Spectrum Disorder / Q000235:genetics; D002675:Child, Preschool; D002872:Chromosome Deletion; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics; D019465:Craniofacial Abnormalities / Q000235:genetics*; D005260:Female; D014644:Genetic Variation; D023281:Genomics; D006330:Heart Defects, Congenital / Q000235:genetics*; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics*; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D056004:Molecular Dynamics Simulation; D020125:Mutation, Missense; D010641:Phenotype; D017510:Protein Folding; D013050:Spectrometry, Fluorescence
chemical_list: C455847:EHMT1 protein, human; D011495:Histone-Lysine N-Methyltransferase
keywords: 9q34 deletion syndrome; DNA sequencing; EHMT1; GLP; Kleefstra syndrome; functional genomics; functional validation; genetic disease; molecular dynamics; molecular modeling