Lrnx9^DBA/2J
QTL Variant Detail

Summary

• QTL variant: Lrnx9^DBA/2J
• Name: learning-contextual 9; DBA/2J
• MGI ID: MGI:2429581
• QTL: Lrnx9 Location: Chr16:29225360-29225471 bp Genetic Position: Chr16, cM position of peak correlated region/allele: 20.26 cM
• QTL Note: genome coordinates based on the marker associated with the peak LOD score

Variant origin

• Strain of Specimen: DBA/2J

Variant description

• Allele Type: QTL
• Mutation: Undefined
• This allele confers increased freezing fear response compared to C57BL/6J. (J:43837)
• Inheritance: Dominant

Notes

Mapping and Phenotype information for this QTL, its variants and associated markers

J:43837

479 (C57BL/6J x DBA/2J)F2 animals were used to map QTLs involved in fear conditioned response. 84 markers at an average density of 20 cM were assayed in a selective genotyping strategy. The C57BL/6J inbred strain displays increased freezing (fear response) when introduced to an environment associated with electroshock (contextual), an auditory cue (conditioned stimulus) associated with electroshock, or an altered environment (altered context) compared to DBA/2J. In F1 animals the freezing phenotype resembles the C57BL/6J parental. Lrnx9, a QTL associated with contextual fear response, mapped to a region of chromosome 16 from 50 cM - 65 cM yielding a maximum LOD score of 4.5 at approximately 60 cM. Increased freezing is associated with DBA/2J-derived alleles and appears to be inherited in a dominant fashion. This locus also shows significant linkage to freezing to a conditioned stimulus (LOD = 3.7) with an additive mode of inheritance. No obvious candidate genes are found at this locus and no epistasis could be detected.

J:65698

A short term selection breeding strategy was used to confirm previously mapped QTLs (Lrncs1, Lrnx10, Lrnx7, Lrnx8, and Lrnx9) associated with contextual fear conditioned learning behavior. Starting with (C57BL/6J x DBA/2J)F2 progenitors, phenotype-drivenselection was used to generate a high line (where animals display high level of fear induced freezing response) and a low line (where animals display high level of fear induced freezing response) for 3 generations. At each generation, animals were assessed for DBA/2J-derived allele distribution at each of the previously mapped QTLs for confirmation of QTLs. Since parental strain DBA/2J displays decreased fear response compared to parental strain C57BL/6J, low lines should increase in DBA/2J-derived allele distribution at the QTLs in successive generations while high lines should decrease in DBA/2J-derived alleles. Lrnx10 on mouse Chromosome 2 (LOD = 3 at D2Mit52), Lrnx7 on mouse Chromosome 3 (LOD = 4.1 at D3Mit51), and Lrnx9 on mouse Chromosome 16 (LOD =4.5 at D16Mit57) were confirmed using this approach. Lrncs1 on mouse Chromosome 1 and Lrnx8 on mouse Chromosome 10 followed the expected allele distribution patterns at each generation but did not reach statistical significance.

References

• Original: J:43837 Wehner JM, et al., Quantitative trait locus analysis of contextual fear conditioning in mice. Nat Genet. 1997 Nov;17(3):331-4
• All: 2 reference(s)