These four MB groups have been incorporated in the World Health Organization (WHO) Classifications of Tumors of the Central Nervous System in 2016 [3] and in 2021 [4], with Group 3 and 4 MBs considered together as MBs without WNT and SHH activation (MBs, non-WNT/non-SHH). The gene discussed is SHH; the disease is Mobius syndrome.