Experiment
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 compared to DBA/2J. In F1 animals the freezing phenotype resembles the C57BL/6J parental. Lrncs1, a QTL associated with fear response to a conditioned stimulus, mapped to a region of chromosome 1 from 60 cM - 90 cM yielding a maximum LOD score of 5.6 at approximately 66.7cM. Increased freezing is associated with DBA/2J-derived alleles and appears to be inherited in a dominant fashion. In this study, Lrncs1 also shows association with contextual fear response (LOD = 3.8), and to emotionality (Flint, J:29027) and open field behavior (Gershenfeld, J:41249) in previous studies. No obvious candidate genes are found at this locus and no epistasis could be detected.
Analysis Tools