Porphyria

Definition

• Any of a group of disorders caused by a defect in the heme synthesis pathway

Types of Porphyrias

Porphyria	Defect	Characteristics
Acute intermittent porphyria	Hydroxymethylbilane synthase	Intermittent attacks of severe abdominal pain triggered by certain stressors
Porphyria cutanea tarda	Uroporphyrinogen decarboxylase	Blistering skin lesions

Pathophysiology

graph TD;

alas[ALA synthase]; style alas fill:none,stroke:none
alad[ALA dehydratase]; style alad fill:none,stroke:none
hmbs[Hydroxymethylbilane synthase]; style hmbs fill:none,stroke:none
upiiis[Uroporphyrinogen III synthase]; style upiiis fill:none,stroke:none
nonenz[Non-enzymatic]; style nonenz fill:none,stroke:none
updc[Uroporphyrinogen decarboxylase]; style updc fill:none,stroke:none
cppo[Coproporphyrinogen oxidase]; style cppo fill:none,stroke:none
ppo[Protoporphyrinogen oxidase]; style ppo fill:none,stroke:none
ferro[Ferrochelatase]; style ferro fill:none,stroke:none

succ[Succinyl CoA]
glycine[Glycine]
daa[delta-aminolevulinic acid]
porpho[Porphobilinogen]
hmb[Hydroxymethylbilane]
uropoiii[Uroporphyrinogen III]
uropoi[Uroporphyrinogen I / Uroporphyrin I]
coproiii[Coproporphyrinogen III]
cpcp[Coproporphyrinogen I / Coproporphyrin I]
protogenix[Protoporphyrinogen IX]
protoix[Protoporphyrin IX]
heme[Heme]

succ --- alas
glycine --- alas
alas --> daa

daa --- alad
alad --> porpho

porpho --- hmbs
hmbs --> hmb

hmb --- upiiis
hmb --- nonenz
upiiis --> uropoiii
uropoiii --- updc

nonenz --> uropoi
uropoi --- updc
updc --> coproiii

coproiii --- cppo
updc --> cpcp
cppo --> protogenix

protogenix --- ppo
ppo --> protoix
protoix --- ferro
ferro --> heme