MECP2 and Rett syndrome: Mutations in the 3′UTR of MECP2 were also found in a rare number of patients with RTT in a study by Santos and colleagues [88]; however, none of the five variants they discovered are found in the putative protein-targeting sites of the UTR; additionally, two had been previously described as polymorphisms, one was present in an unaffected father and another was present in an unaffected mother, suggesting that they are not pathogenic, particularly in the case of the father.