A more specific mechanism could be that increased AICAr alters sonic hedgehog (SHH) and Wnt/β-catenin pathway gene expression, as has been shown in human embryonic carcinoma cell line NT2/D1 during neural differentiation [69], thereby providing a mechanistic connection between the purinergic derangement due to HGprt dysfunction, the irregularities in RG-L morphology and subsequent abnormal proliferation and migration of DA progenitors as discussed above. Here, HPRT1 is linked to embryonal carcinoma.