Investigating the Therapeutic Efficacy of All-trans Retinoic Acid in Autism Spectrum Disorder Patients With 15q11-13 Duplication Syndrome

"Treatment Phase (Duration: 18 months) Intervention: ATRA oral administration using a stepwise titration protocol (detailed below). Patients may discontinue treatment if intolerable adverse events occur; post-withdrawal symptom exacerbation is monitored.~\*Titration Protocol\*~Treatment Cycle (C): 3 weeks per cycle. Dose escalation follows:~Cycle Dosage Duration C1.1 15 mg/m²/day 2 weeks on / 1 week off C1.2 20 mg/m²/day 2 weeks on / 1 week off C1.3 25 mg/m²/day 2 weeks on / 1 week off Blinded Assessments: primary endpoints: ADOS-2 SA score, CARS, SRS, ATEC, Gesell, and Sensory Motor (SM) scales.~Biomarker/Diagnostic tests: blood tests (CBC, liver/kidney function, vitamin panels, ATRA levels, hepatitis markers), neuroimaging (cranial fMRI), neurophysiology (EEG, audiometry), skeletal imaging (limb long-bone radiographs, growth monitoring), and biobanking: 1 blood tube for proteomics (baseline, 6/12/18 months). Repeat all assessments at 6, 12, and 18 months after ATRA treatment."