C57BL/6-derived mice and the Cdh23allele - Background matters.

Abstract

C57BL/6-derived mice are the most utilised mice in biomedical research, and yet actually there is no such thing as a generic C57BL/6 mouse. Instead, there are more than 150 C57BL/6-derived sub-strains recognised by the Mouse Genome Informatics (MGI) database, each of which carry sub-strain-specific fixed genetic differences that can potentially lead to phenotypic differences affecting a single, or multiple biological systems. One of the most widely known strain-specific alleles is the Cdh23allele, a single nucleotide change that predisposes C57BL/6-derived mice to a progressive hearing loss that starts in the high-frequency region. As such, this allele is of particular relevance to auditory researchers. However, a recent study, comparing C57BL/6NTac mice with a co-isogenic strain in which the Cdh23allele has been 'repaired' using genome editing, suggests that the Cdh23allele may have a broader effect on phenotype expressivity of mouse mutants impacting not just the auditory system, but other organ systems as well. Here, using the Cdh23allele as an exemplar, we discuss the importance of knowing, understanding and reporting the genetic background of mouse mutants.