Four of these are involved in growth disorders in humans: ESX1 and GPR50 were found to be involved in growth and pituitary hormone deficiencies [64, 65], while GPC3 and GPC4 were identified as genes causing Simpson-Golabi-Behmel syndrome, a rare X-linked syndrome characterized by pre‐and post‐natal overgrowth [66]. The gene discussed is GPC4; the disease is hypopituitarism.