title: Molecular analysis, pathogenic mechanisms, and readthrough therapy on a large cohort of Kabuki syndrome patients.
abstract: Kabuki syndrome (KS) is a multiple congenital anomalies syndrome characterized by characteristic facial features and varying degrees of mental retardation, caused by mutations in KMT2D/MLL2 and KDM6A/UTX genes. In this study, we performed a mutational screening on 303 Kabuki patients by direct sequencing, MLPA, and quantitative PCR identifying 133 KMT2D, 62 never described before, and four KDM6A mutations, three of them are novel. We found that a number of KMT2D truncating mutations result in mRNA degradation through the nonsense-mediated mRNA decay, contributing to protein haploinsufficiency. Furthermore, we demonstrated that the reduction of KMT2D protein level in patients' lymphoblastoid and skin fibroblast cell lines carrying KMT2D-truncating mutations affects the expression levels of known KMT2D target genes. Finally, we hypothesized that the KS patients may benefit from a readthrough therapy to restore physiological levels of KMT2D and KDM6A proteins. To assess this, we performed a proof-of-principle study on 14 KMT2D and two KDM6A nonsense mutations using specific compounds that mediate translational readthrough and thereby stimulate the re-expression of full-length functional proteins. Our experimental data showed that both KMT2D and KDM6A nonsense mutations displayed high levels of readthrough in response to gentamicin treatment, paving the way to further studies aimed at eventually treating some Kabuki patients with readthrough inducers.
authors.affiliation: Medical Genetics Unit, IRCCS Casa Sollievo Della Sofferenza Hospital, San Giovanni Rotondo, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Micale
authors.forename: Bartolomeo
authors.initials: B
authors.lastname: Augello
authors.forename: Claudia
authors.initials: C
authors.lastname: Maffeo
authors.forename: Angelo
authors.initials: A
authors.lastname: Selicorni
authors.forename: Federica
authors.initials: F
authors.lastname: Zucchetti
authors.forename: Carmela
authors.initials: C
authors.lastname: Fusco
authors.forename: Pasquelena
authors.initials: P
authors.lastname: De Nittis
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Pellico
authors.forename: Barbara
authors.initials: B
authors.lastname: Mandriani
authors.forename: Rita
authors.initials: R
authors.lastname: Fischetto
authors.forename: Loredana
authors.initials: L
authors.lastname: Boccone
authors.forename: Margherita
authors.initials: M
authors.lastname: Silengo
authors.forename: Elisa
authors.initials: E
authors.lastname: Biamino
authors.forename: Chiara
authors.initials: C
authors.lastname: Perria
authors.forename: Stefano
authors.initials: S
authors.lastname: Sotgiu
authors.forename: Gigliola
authors.initials: G
authors.lastname: Serra
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Lapi
authors.forename: Marcella
authors.initials: M
authors.lastname: Neri
authors.forename: Alessandra
authors.initials: A
authors.lastname: Ferlini
authors.forename: Maria Luigia
authors.initials: ML
authors.lastname: Cavaliere
authors.forename: Pietro
authors.initials: P
authors.lastname: Chiurazzi
authors.forename: Matteo Della
authors.initials: MD
authors.lastname: Monica
authors.forename: Gioacchino
authors.initials: G
authors.lastname: Scarano
authors.forename: Francesca
authors.initials: F
authors.lastname: Faravelli
authors.forename: Paola
authors.initials: P
authors.lastname: Ferrari
authors.forename: Laura
authors.initials: L
authors.lastname: Mazzanti
authors.forename: Alba
authors.initials: A
authors.lastname: Pilotta
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Patricelli
authors.forename: Maria Francesca
authors.initials: MF
authors.lastname: Bedeschi
authors.forename: Francesco
authors.initials: F
authors.lastname: Benedicenti
authors.forename: Paolo
authors.initials: P
authors.lastname: Prontera
authors.forename: Benedetta
authors.initials: B
authors.lastname: Toschi
authors.forename: Leonardo
authors.initials: L
authors.lastname: Salviati
authors.forename: Daniela
authors.initials: D
authors.lastname: Melis
authors.forename: Eliana
authors.initials: E
authors.lastname: Di Battista
authors.forename: Alessandra
authors.initials: A
authors.lastname: Vancini
authors.forename: Livia
authors.initials: L
authors.lastname: Garavelli
authors.forename: Leopoldo
authors.initials: L
authors.lastname: Zelante
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Merla
mesh_terms: D000015:Abnormalities, Multiple / Q000188:drug therapy / Q000235:genetics*; D002460:Cell Line; D018389:Codon, Nonsense / Q000187:drug effects; D015331:Cohort Studies; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005145:Face / Q000002:abnormalities*; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000187:drug effects; D056726:Genetic Association Studies; D005839:Gentamicins / Q000494:pharmacology / Q000627:therapeutic use; D057895:Haploinsufficiency; D006402:Hematologic Diseases / Q000188:drug therapy / Q000235:genetics*; D056466:Histone Demethylases / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D059365:Nonsense Mediated mRNA Decay; D009687:Nuclear Proteins / Q000235:genetics; D022821:RNA Splice Sites; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic; D015837:Vestibular Diseases / Q000188:drug therapy / Q000235:genetics*
chemical_list: D018389:Codon, Nonsense; D004268:DNA-Binding Proteins; D005839:Gentamicins; C094289:HOXC6 protein, human; D018398:Homeodomain Proteins; C120898:KMT2D protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D022821:RNA Splice Sites; D056466:Histone Demethylases; C523998:KDM6A protein, human
keywords: KDM6A; KMT2D; Kabuki syndrome; haploinsufficiency; readthrough