A rare autosomal recessive lysosomal storage disease caused by deficiency of the enzyme heparan sulfate sulfatase. It is characterized by behavioral changes, sleep disturbances, mental developmental delays and seizures. The disease is Monarch Disease Ontology id MONDO_0009655 (mucopolysaccharidosis type 3A). Also known as: MPS III A, MPS3A, MPSIIIA, Sanfilippo A, Sanfilippo syndrome a, Sanfilippo syndrome type A, heparan sulfamidase deficiency, mucopolysaccharidosis type IIIA.