SHH and Mobius syndrome: Early gene expression profiling classified MBs in four distinct molecular subtypes: two with mutations in developmental pathways, sonic hedgehog (SHH) and wingless (WNT), and two others, group 3 (G3) characterized by MYC overexpression from amplification in 17% of cases and group 4 (G4) that occurs in the highest number of patients (Fig. 1).