Another study demonstrated that the development of schizophrenia and intellectual disability is associated with the altered methylation levels of FYN, signal transducer and activator of transcription 3 (STAT3), Ras-related C3 botulinum toxin substrate 1 (Rac1), and nuclear receptor 4A2 (NR4A2) as well as changing function of the immune system [54]. Here, STAT3 is linked to schizophrenia.