A method for non-invasive genotyping of APCmin/+ mice using fecal samples

With advances in molecular genetics, there are large numbers of transgenic and knock-out mice being developed. The most common method for genotyping these mice is with DNA isolated from tail, ear or toe tissue, or from blood. These collection techniques however are invasive procedures and are not appropriate for repeat sampling. Recent publications have shown that DNA can be isolated from fecal samples, which allows for non-invasive genotyping [1,2].In this work we describe a method for genotyping APCmin/+ and wild-type mice with DNA isolated from fecal pellets. The APCmin/+ mouse is a model for familial adenomatous polyposis, with the mice highly susceptible to spontaneous intestinal adenoma formation at an early age, and anaemia as a secondary condition [3]. This mouse model is therefore commonly used in cancer research. It has a chemically-induced dominant mutation (base substitution mutation) in the adenomatous polyposis coli (APC) gene which is considered a tumor suppressor gene [4]. It has been shown that the main mechanism for tumor induction is loss of the wild-type (Apc+) allele (ie. loss of heterozygosity) [5,6].The aims of this study were to assess the sensitivity, specificity and reproducibility of genotyping APCmin/+ mice and their wild-type littermates with DNA isolated from their fecal samples.This study has shown that APCmin/+ mice and their wild-type litter mates (> 3 wk) can be genotyped using DNA isolated from whole fecal samples without the need for isolation of the colonic cells from the rest of the fecal mass. The collection technique is non-invasive to the mouse and therefore repeatable. Fecal pellet collection from mice aged greater than 3 wk was very simple, with the majority of mice providing a sample within 1 min. Collection of feces from mice younger than the weaning age (3 wk) was difficult due to their milk diet, and resulted in a poor DNA yield as the sample was small. DNA extraction from a mouse (> 3 wk) fecal pellet resulted in a yie