increased enzyme/coenzyme level abnormal hydroxymethylbilane synthase level increased hydroxymethylbilane synthase level increased HMB synthase level increased porphobilinogen ammonia-lyase (polymerizing) level increased level of the enzyme that catalyzes the head to tail condensation of four porphobilinogen molecules into the linear hydroxymethylbilane while releasing four ammonia molecules MP:0020283 increased uroporphyrinogen synthase level increased HMB-synthase level increased uroporphyrinogen I synthase level increased (4-(2-carboxyethyl)-3-(carboxymethyl)pyrrol-2-yl)methyltransferase (hydrolyzing) level increased uroporphyrinogen synthetase level increased pre-uroporphyrinogen synthase level increased porphobilinogen:(4-[2-carboxyethyl]-3-[carboxymethyl]pyrrol-2-yl)methyltransferase (hydrolysing) level increased porphobilinogen deaminase level increased uroporphyrinogen I synthetase level increased (4-[2-carboxyethyl]-3-[carboxymethyl]pyrrol-2-yl)methyltransferase (hydrolysing) level