Dataset from An Open-Label Extension of Study HGT-SAN-055 Evaluating Long Term Safety and Clinical Outcomes of Intrathecal Administration of rhHNS in Patients With Sanfilippo Syndrome Type A (MPS IIIA)

Sanfilippo syndrome, or Mucopolysaccharidosis (MPS) III, is a rare lysosomal storage disease (LSD) caused by loss in activity of 1 of 9 enzymes necessary for degradation of the glycosaminoglycan (GAG) heparan sulfate (HS) in lysosomes. MPS IIIA results from deficiency of the enzyme heparan N-sulfatase (sulfamidase). In the absence of this enzyme, intermediates of the HS degradation process accumulate in the lysosomes of neurons and glial cells, with lesser accumulation outside the brain. MPS IIIA symptoms arise on average at 7 months of age, with the average age of diagnosis at 4.5 years for the majority of patients. Patients present a wide spectrum and severity of clinical symptoms. The central nervous system (CNS) is the most severely affected organ system in patients with MPS IIIA, evidenced by deficits in language development, motor skills, and intellectual development. In addition, there are abnormal behaviors including but not limited to aggression and excess motor activity/hyperactivity that contribute to disturbances in sleep.Overall, individuals with MPS IIIA have a marked developmental delay and significantly reduced lifespan to 15 years of age on average.The purpose of this study is to collect long term safety and tolerability data in patients with MPS IIIA who previously received rhHNS in study HGT-SAN-055 (NCT01155778).