What is a key developmental feature of Rett syndrome?

A key developmental feature of Rett syndrome is the pattern of developmental regression that occurs after a period of seemingly normal development, typically around 6 to 18 months of age. Initially, children with Rett syndrome appear to develop normally during the first few years of life, reaching typical milestones such as walking and language skills. However, following this initial phase, they experience a loss of previously acquired skills, which is a hallmark of the syndrome.

This developmental regression can manifest as the loss of purposeful hand skills, the onset of repetitive hand movements, and deteriorating social and communication abilities. Such a regression is critical in diagnosing Rett syndrome and distinguishes it from other developmental disorders that typically present with persistent delays from birth. Therefore, the presence of normal early development followed by a significant decline in function is what characterizes this condition.