The Natural History Study of Patients With Sanfilippo Disease(s) (MPS3)

Inclusion Criteria: 1. IRB - approved informed consent/assent signed by subject and/or parent(s) or legal guardian(s). 2. Genetically confirmed diagnosis of MPS III disease Genomic DNA analysis demonstrating a homozygous or compound heterozygous pathogenic variants in SGSH (type A), NAGLU (type B), HGSNAT (type C), or N- acetylglucosamine-6-sulfatase GNS (type D). 3. Male or female; five years of age and older 4. Negative urine pregnancy test at screening for female subjects with child-bearing potential Exclusion Criteria: 1. Unwilling or unable to follow protocol requirements as per principal investigator 2. Any serious or chronic medical illness, including significant cardiac or severe debilitating pulmonary disease as determined by the investigator. 3. Any medical condition that, in the opinion of the PI, would place a subject at undue risk 4. Inability to cooperate for clinical and safety data collection 5. Use of genistein or Miglustat within one week of the study 6. Evidence of hepatitis B or hepatitis C infection upon serological testing at screening 7. Currently participating in another interventional drug trial or has completed an interventional trial less than one month prior to the screening visit