Arnt and Gdi2 emerged as candidate LMD-inducing genes from a study in which SB transposon mobilization in Math1+ GNPs in Patched+/− mice caused the typically localized, Shh-driven medulloblastomas to disseminate widely throughout the spinal leptomeninges [19]. The gene discussed is ARNT; the disease is Langer mesomelic dysplasia.