UBE3A and autism: Moreover, several HOXA5 candidate target genes identified such as Cbln1, Cbln3, Homer3, Grm4, En2, Atp2a3, Fat2, and Car8, are also downregulated in a recent mouse model of ASD, generated by increasing dosage of E3 ubiquitin ligase UBE3A, which recapitulates a highly penetrant type of autism in humans (Smith et al., 2011; Krishnan et al., 2017).