We next extended the genetic analysis to the retina. We have shown previously that Pcdhg genes are required for the survival of many neuronal subpopulations in the developing inner retina, but appear to be dispensable for synapse formation and function (Lefebvre et al., 2008). To generate retina-specific knockouts of TCKO and TAKO mutants, trans-heterozygous animals containing one conditional Pcdhgfcon3 allele (Lefebvre et al., 2008; Prasad et al., 2008) and one Pcdhgtcko or Pcdhgtako allele were produced. Upon retina-specific recombination of Pcdhgfcon3 that leads to a functionally null allele, the remaining Pcdhg isoforms are only expressed from the Pcdhgtcko or Pcdhgtako allele, providing a convenient way to conditionally inactivate the three C-type or A-type isoforms in postnatal animals.
