LAUSR

Since its first description in 2009,1 the AldaraTM (MEDA Pharma GmbH, Bad Homburg, Germany)-induced psoriasiform dermatitis (AIPD) model has become a most commonly used mouse model of plaque psoriasis. It is mostly conducted in the C57Bl/6 mouse strain. Two substrains of this mouse strain, C57Bl/6J and C57Bl/6N, are in parallel widely used for research purposes. The two substrains are phenotypically identical but genetically differ by 34 SNPs, two indels and 15 gene variants that overlap a gene.2–4 Notably, gene knockout and transgenic mice on the C57Bl/6 background are often held on an intermediate genotype between the two substrains due to incomplete backcrossing after genetic manipulation. This issue has become even more common in recent years with the International Knockout Mouse Consortium’s (IKMC) decision to preferentially generate genetic knockouts in C57Bl/6N embryonic stem cells,4 while, in contrast, most investigators still preferably use C57Bl/6J mice.