*2.2. PCR Genotyping*

Mouse genomic DNA samples obtained from tail snips were verified by PCR using primers *Dhdds*-FWD: 5-GTGTCATCCCCTGCTGCAGAT-3 and *Dhdds*-REV: 5-TGGGTGTAGTG-GCTCAGGTC-3 for genotype identification of floxed *Dhdds* alleles designed in a region which was conserved in both wild type (WT) and floxed alleles and also in the region flanking the loxP sites. The expected PCR product sizes for the WT and floxed alleles are 393 and 517 bp, respectively, thus differentiating WT, heterozygous floxed, and homozygous floxed alleles. PCR verification of Cre transgene modification was carried out using the following forward and reverse primer sets for Cre RPE 5-AGGTGTAGAGAAGGCACTTAGC-3 and 5-CTAATCGCCATCT-TCCAGCAGG-3, respectively, yielding a 411 bp product. RPE specific expression and activity of Cre-recombinase in VMD2-RPE Cre was verified by breeding these mouse lines against an ZsGreen reporter mouse strain (B6.Cg-*Gt(ROSA)26Sortm6(CAG-ZsGreen1)Hze*/J, Stock# 007906; The Jackson Laboratory, Bar Harbor, ME, USA) and monitoring ZsGreen expression in the retina.
