First Diagnostic Questionnaire for Assessing Patients' Social Functioning: Comprehensive DDX3X Syndrome Patient Profile.

Background/Objectives: DDX3X syndrome is often misdiagnosed as autism spectrum disorder (ASD, Rett Syndrome, and Dandy-Walker Syndrome). Precise phenotyping is needed with reference to neurodevelopmental diagnosis. Observation of behavior and communication in parents with DDX3X syndrome in the USA, France, and Poland; conversations with the parents of patients; and rudimentary information in evidence-based medical articles prompted us to identify differences in communication, play, and social interaction between children with ASD only, those with both ASD and DDX3X, and those with DDX3X only. Methods: As diagnostic tool for DDX3X patients, we created a questionnaire divided into four sections: medical, social, play, and communication. Results: The results showed inconsistent diagnoses in different countries where children could have been diagnosed with DDX3X. In a comparative analysis, individuals with DDX3X exhibited greater social skills than individuals with ASD. Furthermore, those with DDX3X demonstrated higher levels of social functioning compared to children with ASD. Therefore, parents of children recently diagnosed with ASD or similar conditions are encouraged to complete a survey to determine if their child is likely to have features of DDX3X syndrome. Conclusion: Identification of early behavioral markers that differentiate children with ASD and those with DDX3X could lead to the earliest opportunity for identification and intervention, and can significantly impact developmental trajectories, leading to better long-term outcomes.