GPT and mucopolysaccharidosis type 3: Other gastrointestinal manifestations of Sanfilippo syndrome include elevations in liver enzymes (alanine aminotransferase ≤ 3.5 times upper limit of normal [ULN]; aspartate aminotransferase ≤ 1.5 × ULN) and hepatomegaly, which do not typically require intervention.