Mouse genotyping issues - (Mar/13/2013 )

Hi all,

Wondering if you can help. I am having some issues with genotyping, using a traditional KO LacZ gene targeting strain - and although I get exactly the predicted bands for LacZ, WT and both for het that the original paper predicted I am at times still seeing protein and transcripts of the knocked out protein in the tissue of a KO mouse. I am wondering if years of inbreeding may have introduced some mutation, not really sure how to test this. Any ideas would really help, thanks!

Functional pseudogene? Is it possible that the KO was a not a full length KO?

Spontaneous mutations do happen, but they are relatively rare, and it is unlikely that it would return a gene that has been removed. Perhaps there was a recombination event in the original mouse that resulted in the KO being only one allele?