Ontology of Biological Attributes term OBA_2041930 (level of heparan sulfate glucosamine 3-O-sulfotransferase 1 in blood serum) is the amount of a heparan sulfate glucosamine 3-O-sulfotransferase 1 when measured in blood serum. Also known as: blood serum heparan sulfate glucosamine 3-O-sulfotransferase 1 amount.