It is additionally known that 4% of MBs have homozygous mutations or deletions of UTX/KDM6A usually in male patients, but are also present in female patients in case they have lost an X chromosome (Xp11.3), with a greater enrichment in GR4 tumors (Dubuc et al., 2013; Jones et al., 2013). The gene discussed is KDM6A; the disease is Mobius syndrome.