Even though approximately 600 identified mutations leading to RTT have been detected in MECP2, genetic mutations that lead to 8 missense and nonsense mutations in the MeCP2 protein (R106W, R133C, T158M, R168X, R255X, R270X, R294X, and R306C) comprise about 70% of all mutations in RTT (Neul et al., 2008). Here, MECP2 is linked to Rett syndrome.