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Porphyrias

Inherited and acquired Hepatic and erythropoietic all are autosomal dominant except CEP Mnemonic to remember heme synthesis pathway Some Great Doctors Palpate Heart Under Cover & Produces Pure Heme Enzymes -As Ad U1 U3 Ud Co Po F Reason for abdominal pain and neuropsychiatric symptoms The exact mechanism is not known but it is thought to be due to accumulation of ALA, phorphobilinogen and hydroxymethylbilane. The neurological symptoms are due to decrease activity of tryptophan pyrrolase, which causes accumulation of tryptophan and serotonin (5-hydroxy tryptamine) ALA causes impaired nerve conduction Reason for photosensitivity and cutaneous manifestations Porphyrinogen get accumulated when defect is below the hydroxymethylbilane. On oxidation these porphyrinogens are converted into porphyrins and cause photosensitivity. When exposed to light, porphyrin reacts with O2 to from free radicals (ROS). Reactive oxygen species causes lysosomal damage and release of degradative enzymes which lead to the cutaneous manifestations (skin injuries).