| A rare X-linked intellectual disability syndrome with characteristics of psychomotor delay, intellectual deficit, hydrocephalus, and mild facial anomalies. Prevalence is unknown, but the syndrome was originally described in a large Scottish family. Mutations in the AP1S2 gene (Xp22), coding for a subunit of the clathrin-associated adaptor protein complex involved in intracellular protein trafficking and synaptic vesicle recycling, have been identified in seven families. |
