title: Characterization of two novel intronic OPA1 mutations resulting in aberrant pre-mRNA splicing.
abstract: We report two novel splice region mutations in OPA1 in two unrelated families presenting with autosomal-dominant optic atrophy type 1 (ADOA1) (ADOA or Kjer type optic atrophy). Mutations in OPA1 encoding a mitochondrial inner membrane protein are a major cause of ADOA.
  
  
  
  We analyzed two unrelated families including four affected individuals clinically suspicious of ADOA. Standard ocular examinations were performed in affected individuals of both families. All coding exons, as well as exon-intron boundaries of the OPA1 gene were sequenced. In addition, multiplex ligation-dependent probe amplification (MLPA) was performed to uncover copy number variations in OPA1. mRNA processing was monitored using RT-PCR and subsequent cDNA analysis.
  
  
  
  We report two novel splice region mutations in OPA1 in two unrelated individuals and their affected relatives, which were previously not described in the literature. In one family the heterozygous insertion and deletion c.[611-37_611-38insACTGGAGAATGTAAAGGGCTTT;611-6_611-16delCATATTTATCT] was found in all investigated family members leading to the activation of an intronic cryptic splice site. In the second family sequencing of OPA1 disclosed a de novo heterozygous deletion c.2012+4_2012+7delAGTA resulting in exon 18 and 19 skipping, which was not detected in healthy family members.
  
  
  
  We identified two novel intronic mutations in OPA1 affecting the correct OPA1 pre-mRNA splicing, which was confirmed by OPA1 cDNA analysis. This study shows the importance of transcript analysis to determine the consequences of unclear intronic mutations in OPA1 in proximity to the intron-exon boundaries.
authors.affiliation: Division of Human Genetics, Department of Pediatrics, Inselspital, Bern University Hospital, University of Bern, Freiburgstrasse 15, 3010, Bern, Switzerland.|Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Bern, Switzerland.
authors.forename: Ramona
authors.initials: R
authors.lastname: Bolognini
authors.affiliation: Department of Ophthalmology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Christina
authors.initials: C
authors.lastname: Gerth-Kahlert
authors.affiliation: Department of Ophthalmology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
authors.forename: Mathias
authors.initials: M
authors.lastname: Abegg
authors.affiliation: Division of Human Genetics, Department of Pediatrics, Inselspital, Bern University Hospital, University of Bern, Freiburgstrasse 15, 3010, Bern, Switzerland.
authors.forename: Deborah
authors.initials: D
authors.lastname: Bartholdi
authors.affiliation: Division of Human Genetics, Department of Pediatrics, Inselspital, Bern University Hospital, University of Bern, Freiburgstrasse 15, 3010, Bern, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Mathis
authors.affiliation: Department of Ophthalmology, Cantonal Hospital St. Gallen, St. Gallen, Switzerland.
authors.forename: Veit
authors.initials: V
authors.lastname: Sturm
authors.affiliation: Division of Human Genetics, Department of Pediatrics, Inselspital, Bern University Hospital, University of Bern, Freiburgstrasse 15, 3010, Bern, Switzerland.
authors.forename: Sabina
authors.initials: S
authors.lastname: Gallati
authors.affiliation: Division of Human Genetics, Department of Pediatrics, Inselspital, Bern University Hospital, University of Bern, Freiburgstrasse 15, 3010, Bern, Switzerland. andre.schaller@insel.ch.
authors.forename: André
authors.identifier: 0000-0001-5174-5764
authors.initials: A
authors.lastname: Schaller
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D004252:DNA Mutational Analysis; D005091:Exons; D020558:GTP Phosphohydrolases / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D054643:INDEL Mutation; D007438:Introns; D029241:Optic Atrophy, Autosomal Dominant / Q000235:genetics*; D010375:Pedigree; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism*; D012326:RNA Splicing; D012160:Retina / Q000000981:diagnostic imaging; D041623:Tomography, Optical Coherence
chemical_list: D012322:RNA Precursors; D004247:DNA; D020558:GTP Phosphohydrolases; C415198:OPA1 protein, human
keywords: Autosomal dominant optic atrophy; Kjer type optic atrophy; OPA1; Optic neuropathies; Splice site mutation