A pancreas specificPtf1a-driven Cre mouse line causes paternally transmitted germline recombination

Cre- lox P recombination system is a commonly used tool to achieve site-specific genetic manipulation in genome. For multiple Cre driver mouse lines, parental transmissions of recombined flox alleles are reported. Ptf1a -driven Cre lines are widely used to achieve genetic manipulation in a pancreas specific manner. Herein, we report germline recombination in breedings when Cre allele is retained paternally in Ptf1a tm1(cre)Hnak . The germline recombination frequency changed depending on the target allele. Therefore, unless the reporter allele is on the target gene, the reporter activity is to be validated. Overall, we highlight that all Ptf1a -driven Cre mouse lines should be genotyped for possible germline recombination and we advise the maternal transmission of the Cre to progeny.