title: Targeting of Slc25a21 is associated with orofacial defects and otitis media due to disrupted expression of a neighbouring gene.
abstract: Homozygosity for Slc25a21(tm1a(KOMP)Wtsi) results in mice exhibiting orofacial abnormalities, alterations in carpal and rugae structures, hearing impairment and inflammation in the middle ear. In humans it has been hypothesised that the 2-oxoadipate mitochondrial carrier coded by SLC25A21 may be involved in the disease 2-oxoadipate acidaemia. Unexpectedly, no 2-oxoadipate acidaemia-like symptoms were observed in animals homozygous for Slc25a21(tm1a(KOMP)Wtsi) despite confirmation that this allele reduces Slc25a21 expression by 71.3%. To study the complete knockout, an allelic series was generated using the loxP and FRT sites typical of a Knockout Mouse Project allele. After removal of the critical exon and neomycin selection cassette, Slc25a21 knockout mice homozygous for the Slc25a21(tm1b(KOMP)Wtsi) and Slc25a21(tm1d(KOMP)Wtsi) alleles were phenotypically indistinguishable from wild-type. This led us to explore the genomic environment of Slc25a21 and to discover that expression of Pax9, located 3' of the target gene, was reduced in homozygous Slc25a21(tm1a(KOMP)Wtsi) mice. We hypothesize that the presence of the selection cassette is the cause of the down regulation of Pax9 observed. The phenotypes we observed in homozygous Slc25a21(tm1a(KOMP)Wtsi) mice were broadly consistent with a hypomorphic Pax9 allele with the exception of otitis media and hearing impairment which may be a novel consequence of Pax9 down regulation. We explore the ramifications associated with this particular targeted mutation and emphasise the need to interpret phenotypes taking into consideration all potential underlying genetic mechanisms.
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: Simon
authors.initials: S
authors.lastname: Maguire
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: Jeanne
authors.initials: J
authors.lastname: Estabel
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: Neil
authors.initials: N
authors.lastname: Ingham
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: Selina
authors.initials: S
authors.lastname: Pearson
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: Edward
authors.initials: E
authors.lastname: Ryder
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: Damian M
authors.initials: DM
authors.lastname: Carragher
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom; Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Walker
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: James
authors.initials: J
authors.lastname: Bussell
authors.affiliation: Department of Haematology, Cambridge Institute for Medical Research, Cambridge, Cambridgeshire, United Kingdom.
authors.forename: Wai-In
authors.initials: WI
authors.lastname: Chan
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Keane
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: Adams
authors.affiliation: Department of Pathology and Infectious Diseases, Royal Veterinary College, Hatfield, Hertfordshire, United Kingdom.
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Scudamore
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Lelliott
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: Ramiro
authors.initials: R
authors.lastname: Ramírez-Solis
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: Natasha A
authors.initials: NA
authors.lastname: Karp
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: Karen P
authors.initials: KP
authors.lastname: Steel
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: Jacqueline K
authors.initials: JK
authors.lastname: White
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: Anna-Karin
authors.initials: AK
authors.lastname: Gerdin
mesh_terms: D000483:Alleles; D000818:Animals; D029382:Dicarboxylic Acid Transporters / Q000172:deficiency / Q000235:genetics*; D005091:Exons; D005260:Female; D005786:Gene Expression Regulation; D005818:Genetic Engineering; D006720:Homozygote; D006801:Humans; D008297:Male; D026901:Membrane Transport Proteins / Q000172:deficiency / Q000235:genetics*; D051379:Mice; D018345:Mice, Knockout; D033681:Mitochondrial Membrane Transport Proteins / Q000172:deficiency / Q000235:genetics*; D009056:Mouth Abnormalities / Q000235:genetics* / Q000473:pathology; D009154:Mutation; D010033:Otitis Media / Q000235:genetics* / Q000473:pathology; D051764:PAX9 Transcription Factor; D051761:Paired Box Transcription Factors / Q000172:deficiency / Q000235:genetics*; D015398:Signal Transduction
chemical_list: D029382:Dicarboxylic Acid Transporters; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D051764:PAX9 Transcription Factor; D051761:Paired Box Transcription Factors; C488759:Pax9 protein, mouse; C000594005:Slc25a21 protein, mouse