Slc25a21_expression_profile
Homozygosity for Slc25a21<tm1a(KOMP)Wtsi> results in mice exhibiting orofacial abnormalities, alterations in carpal and rugae structures, and hearing impairment and inflammation in the middle ear. Unexpectedly, 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 wildtype. This led us to explore the genomic environment of Slc25a21 and discover that expression of Pax9, located 3’ of the target gene, was reduced in Slc25a21<tm1a(KOMP)Wtsi/tm1a(KOMP)Wtsi> mice. We hypothesise that the presence of the selection cassette affected expression of neighbouring genes, including down regulation of Pax9. The phenotypes we observed in Slc25a21<tm1a(KOMP)Wtsi/tm1a(KOMP)Wtsi mice> were broadly consistent with a hypomorphic Pax9 allele with the exception of otitis media and hearing impairment which may be novel consequences of Pax9 down regulation. To further explore the ramifications associated with this particular targeted mutation we aim to use RNAseq to identify other genes in the vicinity whose expression level has been altered by the targeting event.