Rett syndrome is a neurodevelopmental disorder caused by mutations in MECP2. The disease is characterized by early neurological regression following a normal initial development. The diagnosis is a clinical one, based on major and minor diagnostic criteria. This study, in a group of patients from a single tertiary center, aimed to evaluate the efficiency of clinical diagnosis and to see if there was a diagnostic delay. A second aim was to investigate genotype-phenotype correlations, based on Pineda scores. In this study, sixteen patients with a median age of 6.5 years (2.5-22 years) were included, following molecular confirmation of clinical diagnosis. The median age at the onset of symptoms and the median age at clinical diagnosis was 1.5 years and 2.5 years, respectively, the difference being statistically significant. Considering the Rett syndrome diagnostic criteria, initially regulated in 2002 and revised in 2010, seven and two patients in our group, respectively, did not meet the main criteria. Pineda scores among mutation groups were statistically not different. To conclude, the present study revealed presence of a diagnostic delay. The challenge may be that the patients do not exhibit full-blown clinical picture initially. No genotype-phenotype correlations were detected in clinical severity, as measured by Pineda scores. Moreover, the diagnostic criteria revised in 2010 are more comprehensive as compared to the 2002 criteria; however, further revision may increase diagnostic sensitivity.

Keywords: MECP2, Rett syndrome, diagnostic delay, genotype-phenotype correlation