Mutations in "Methyl-CpG-Binding protein 2" ("MECP2") are commonly associated with the neurodevelopmental disorder Rett syndrome (RTT). However, some people with RTT do not have mutations in "MECP2," and interestingly there have been people identified with "MECP2" mutations that do not have the clinical features of RTT. In this report we present four people with neurodevelopmental abnormalities and clear RTT-disease causing "MECP2" mutation but lacking the characteristic clinical features of RTT. One patient's symptoms suggest an extension of the known spectrum of "MECP2" associated phenotypes to include global developmental delay with obsessive compulsive disorder and attention deficit hyperactivity disorder. These results reemphasize that RTT should remain a clinical diagnosis, based on the recent consensus criteria.