SFRP4 and Anxiety: Some of these genes have previously been shown to be involved in natural behavioural variation and neural development, SFRP4 and LOC100136711 (the probeset was previously annotated as LOC770352, [21]) have, for example, been linked to anxiety in the chicken [21], demonstrating some overlap in the genetic architecture of intra-individual variation in behaviour based on anxiety-related traits and anxiety itself.