A recent systematic review focusing on male patients carrying pathogenic or likely pathogenic variants in the MECP2 gene documented 49 cases (46.2%) of MRXS13, 32 cases (30.2%) of severe neonatal encephalopathy, and 25 cases (23.6%) of PPMX. Here, MECP2 is linked to X-linked intellectual disability-psychosis-macroorchidism syndrome.