MECP2 and neurodevelopmental disorder: This study evaluates the real-world effectiveness and side effect profile of Trofinetide in 55 individuals (50 females, 5 males) with RTT or <i>MECP2</i>-related neurodevelopmental disorders over a 12-month period.<h4>Methods</h4>Data was collected through clinic assessments and caregiver reports.<h4>Results</h4>Results demonstrated that 75.9% of individuals experienced some improvement in RTT symptoms by caregiver report, particularly in engagement, communication, and motor skills.