Together, these data provide further genetic evidence that EN2 might act as an ASD susceptibility locus, and they suggest that a risk allele that perturbs the spatial/temporal expression of EN2 could significantly alter normal brain development.
Further support that EN2 is a possible ASD susceptibility gene requires the identification of a risk allele, a DNA variant that is consistently associated with ASD but is also functional.
Elevated 5-hydroxymethylcytosine in the Engrailed-2 (EN-2) promoter is associated with increased gene expression and decreased MeCP2 binding in autism cerebellum.
As such, En2<sup>-/-</sup> mice display the behavioral deficits and neural impairments characteristic of the core symptoms associated with autism spectrum disorder (ASD).
Accordingly, mice lacking the En2 homeodomain (En2<sup>hd/hd</sup>, referred to as En2<sup>-/-</sup>) show molecular, anatomical and behavioral "ASD-like" features.