MECP2 gene analysis in classical Rett syndrome and in patients with Rett-like features

Objective: To discuss the diagnostic criteria for Rett syndrome based on mu tational screening of the methyl-CpG-binding protein 2 gene (MECP2) in pati ents with classic Rett syndrome and patients with Rett-like features. Metho ds: Thirty-nine patients with classical Rett syndrome, one with preserved s peech variant (PSV), and 12 patients with developmental delay and some feat ures of Rett syndrome were recruited for sequence analysis of the MECP2 gen e coding region. The phenotype of the patients was correlated with the pres ence and type of the mutation as well as the X-chromosome inactivation (XCI ) pattern. Results: MECP2 gene mutations were found in 100% of the patients with classical Rett syndrome originating from Finland. One novel mutation, P127L, was detected in a patient with PSV. No mutations were found in othe r cases. The XCI status was found to be random in 72% of the patients with classical Rett syndrome, including the patient with PSV and all patients wi th developmental delay informative for the analysis. Conclusions: An MECP2 mutation can be found in almost every patient with classical Rett syndrome. More patients need to be analyzed in order to clarify the mutation prevale nce in patients with atypical Rett syndrome and in patients with mental ret ardation.