Interestingly, regions within both Gpc4 and RPTPδ have been identified as potential HARs (Doan et al., 2016), and two cases of ASD with intellectual disability (ID) were found that have point mutations in HARs of Gpc4 causing a significant decrease in Gpc4 expression (Doan et al., 2016). This evidence concerns the gene GPC4 and Intellectual disability.