Stephenson Syndrome: Rare Genetic Neurodevelopmental Disorder

Stephenson syndrome is an ultra-rare autosomal dominant disorder caused by de novo mutations in SUPT5H (SPT5 homolog), a transcription elongation factor. Fewer than 20 cases reported.

Features

• Global developmental delay / intellectual disability.
• Autism spectrum features.
• Speech/language impairment.
• Hypotonia, motor delays.
• Seizures (variable).
• Dysmorphic features (broad forehead, hypertelorism, thin upper lip).
• Cardiac, renal, GI, vision, hearing anomalies reported.

Management

Multidisciplinary: neurology, genetics, cardiology, nephrology, developmental therapies (PT/OT/SLP), educational support, seizure management. No cure; symptomatic care. Genetic counseling for recurrence risk (low if de novo, 50% if inherited).

Research ongoing; connect with rare disease networks (e.g., Simons Searchlight).