MECP2 and neurodevelopmental disorder: <h4>Background</h4>Rett syndrome (RTT) is a rare neurodevelopmental disorder linked with MECP2 variants, frequently presenting with movement disorders (MDs).<h4>Objectives</h4>This study examined the frequency, types, and associations of MDs with RTT characteristics and severity.<h4>Methods</h4>Twenty female patients (median age 11 years, range 3-40) with MECP2 variants were recruited and assessed using disease severity and MD scales, alongside videotaped neurological examinations.<h4>Results</h4>Prevalent MD was hypokinetic in 55% of the patients and hyperkinetic in 45%.