AXB/BXA Family


The AXB and BXA set of recombinant inbred (RI) strains were derived from a reciprocal cross between A/J (A) and C57BL/6J (B). A particular advantage of this RI set (shared with BXD) is that the two parental strains have both been sequenced and are known to differ at approximately 1.80 million SNPs. Variants (mostly single nucleotide polymorphisms and insertion-deletions) that may produce interesting phenotypes can be located efficiently. The zoomable physical maps in WebQTL display the positions of this A-type versus B-type SNPs down at high resolution.

Data acquired using AXB and BXA subsets should be combined; the only difference being the polarity of intercross matings that generated (A x B)F1s and (B x A)F1s. AXB and BXA strains were all produced by Muriel Nesbitt at UCSD in the mid and late 1970s and first used in the early 1980s (Skamene et al., 1984; Peleg and Nesbitt, 1984; Marshal et al., 1992). The set was imported into The Jackson Laboratory by Beverly Paigen (Pgn) in the early 1990s. As of 2004, approximately 25 viable and fully independent AXB/BXA strains are available. These strains are not segregating for the more recent A/J retrotransposon mutation in the dysferlin gene (Ho et al., 2004).

Approximately 122 traits are currently included in the AXBXA Phenotypes database (July 2005).

All strains have been genotyped using the Wellcome-CTC-Illumina set of SNPs (n = 13377), as well as some microsatellites, and other markers. WebQTL exploits a total of 8514 markers that are infomative in this mapping panel (Aug 2005).

There are a total of approximately 1600 known recombinations (corrected for five "duplicate strains") in the AXB/BXA set; an average of 54.4 recombinations per strain (Shifman et al., 2006). 

Several nominally independent strains in the AXB and BXA sets are very closely related. These duplicates should not be used without special statistical precaution. The most obvious option is to combine and average data from these strains except when their phenotypes differ significantly (Taylor 1996; Williams et al., 2001). 

AXB13=AXB14: 92.74% identity in an analysis of 8429 markers. 
AXB18=AXB19=AXB20: 97 to 99% identity (AXB18 to AXB19 = 98.16% identity, AXB18 to AXB20 = 95.72% identity, AXB19 to AXB20 = 97.34% identity n an analysis of 8429 markers) 
BXA8=BXA17: 99.79% identity in an analysis of 8429 markers. (Updated from Williams et al. 2001).

How to obtain these strains: Please see

For more details on the history, generation, and use of RI strains as genetic reference populations for systems genetics please see Silver (1995). Additional useful literature links are provided in the References link at the top center of this page.