Through high density SNP analysis, some AXB and BXA recombinant inbred strains were shown to be the same or nearly the same genetically. AXB18/Pgn, AXB19/Pgn, and AXB20/Pgn were found to be highly similar in their overall genomes, but with particular Chromosomes differing between them. Two of these "sister" strains were renamed. AXB19/Pgn was designated the primary strain since it has the best traceable history, and therefore its name remained unchanged. AXB18/Pgn was renamed AXB19a/Pgn and AXB20/Pgn was renamed AXB19b/Pgn. In general, the "sister" strains (those with suffixes of a or b) should not be used for primary screening/QTL mapping. However, if a QTL is located in a region of difference in a sister recombinant inbred then this strain can serve as a "near congenic" for additional analysis.

The AXB and BXA set of RI strains are useful in the genetic analysis of several complex diseases including cardiovascular disease, diabetes, cancer, cleft palate, and hydrocephalus. The individual strains within the RI set also differ in their susceptibility to infectious diseases and in their responses to alcohol, stress, and endotoxin.

The strain distribution pattern (SDP) for the AXB RI strains is available through the Mouse Genome Informatics Contributed Data Sets and Gene Network. Additional tools and information are presented through the Mouse Phenome Database Specialized Strain Panel Query Form, and Gene Network .

The AXB and BXA recombinant inbred (RI) set of strains were originally generated and maintained at the University of California, San Diego, and have been imported into The Jackson Laboratory. There were originally 51 AXB and BXA strains derived from the C57BL/6J (Stock No. 000664) and A/J (Stock No. 000646) progenitor strains. Many of the original strains are either extinct or were discarded due to genetic contamination. Please refer to Sampson et al., 1998 for more information.