MECP2 duplication syndrome in both genders.

BACKGROUND

Duplications involving the methyl-CpG-binding protein 2 gene (MECP2) locus at Xq28 have been frequently identified in male patients who exhibit a phenotype unique from that of Rett syndrome, which is mainly characterized by severe mental retardation, recurrent infections, and epilepsy. This combination of features is recognized as MECP2 duplication syndrome.

METHODS

Genomic copy number was investigated for patients with unexplained mental retardation, and phenotypic features of the patients having interstitial duplications including MECP2 were analyzed.

RESULTS

Three male and one female patients with MECP2 duplication were identified. The phenotypic features of all the four patients were compatible with MECP2 duplication syndrome. The X-chromosome inactivation (XCI) pattern was analyzed in the female patient, identifying a skewed XCI that activated the X-chromosome containing the MECP2 duplication. Her mother possessed the same MECP2 duplication and a random XCI pattern but exhibited no phenotypic features, indicating a nonsymptomatic carrier. The brain magnetic resonance imaging revealed periventricular cystic lesions in all four patients, including the female patient.

CONCLUSION

This study suggested clinical implications of the MECP2 duplication syndrome not only in the male but also in female patients with unexplained mental retardation.