Adult‐onset drug‐resistant progressive epilepsy in a patient with novel <i>MECP2</i> mutation

Mutations in the Methyl-CpG-binding protein 2 (MECP2) gene are associated with a spectrum of neurologic disorders, most commonly of which is Rett syndrome (RTT). As these mutations occur in germ cells, neurologic symptoms usually begin in early childhood. Seizures, a common feature of MECP2-related disorders, often occur later in childhood or early adolescence. However, there has never been a documented case of progressive epilepsy and cognitive decline with onset in adulthood. Here, we present a novel case of a woman with normal developmental history who develops progressive drug-resistant epilepsy at age 27. Whole-exome sequencing revealed a loss-of-function mutation in the MECP2 gene: c.1059_1190del132ins24 that has not been previously reported. This report expands the phenotypic spectrum of MECP2-related epilepsy.