eNews June 11, 2012

ICR/HaJ: an inbred ICR strain

If you're looking for an alternate control strain for NOD/ShiLtJ (NOD, 001976) as you investigate the genetics of diabetes susceptibility, consider inbred strain ICR/HaJ (009122).

“Swiss”-derived, outbred mice, including CD-1(Crl:CD-1®(ICR), Charles River) and ICR (ICRTac:ICR, Taconic; Hsd:ICR (CD-1®), Harlan), are notable for their excellent fecundity.  Inbred ICR/HaJ, which we imported from Dr. Rosemary Elliott at the Roswell Park Cancer Institute and is derived from ICR, matches this fecundity. ICR/HaJ shares the diabetogenic H2g7 MHC haplotype with NOD, which is also ICR-derived. Unlike NOD, however, ICR/HaJ is insulitis-and diabetes-free. Hence, it provides another H2g7-matched control to complement NOR/LtJ (NOR, 002050), a recombinant congenic strain that shares approximately 88% genome identity with NOD.

A recent strain survey indicates that ICR/HaJ has a higher percentage of invariant natural killer cells (cells with known immunoregulatory functions) in lymphoid organs than NOD (Chen et al. 2012).

You can find single nucleotide polymorphisms (SNPs) that distinguish ICR/HaJ, NOD, and other inbred strains in the Center for Genome Dynamics database. You also can compare SNPs across specific genomic regions of ICR/HaJ, NOD, and other inbred strains by using the “Compare 2 strains” feature of the Mouse Phenome Database.

Also of interest, inbreeding of the ICR/HaJ strain has fixed genes for susceptibility to certain carcinogens: following 24 weeks of subcutaneous injections of 1,2-dimethylhydrazine, all ICR/HaJ mice develop colon tumors and adenocarcinomas (Jacoby et al. 1994).