Column 1 gives the biosynthetic pathway of heme, in which eight molecules of aminolevulinic acid (ALA) are transformed into one molecule of heme; column 2, the enzymes that catalyze the reactions and their cellular locations (mito, mitochondria; cyto, cytoplasm); column 3, the form of porphyria associated with a defect in each of the enzymes; column 4, the main site of the enzyme defect; column 5, the inheritance pattern (all are autosomal); column 6, the presence of light sensitivity; and column 7, the presence of neurological symptoms.
| Compound |
Enzyme |
Porphyria Type |
Main Site of Defect |
Pattern of Inheritance |
Light Sensitivity |
Neurological Symptoms |
| Glycine + Succinyl CoA |
ALA Synthase (mito) |
- |
- |
- |
- |
- |
| Aminolevulinic acid (ALA) |
ALA dehydratase (cyto) |
Doss porphyria |
Liver |
Recessive |
No |
Yes |
| Porphrobilinogen (PBG) |
PBG deaminase (cyto) |
Acute intermittent porphyria |
Liver |
Dominant |
No |
Yes |
| Preuroporphyrinogen |
UPG synthase (cyto) |
Erythropoetic porphyria
(Gunther's disease) |
Bone marrow |
Recessive |
Yes |
No |
| Uroporphyrinogen I, III (UPG) |
UPG decarboxylase (cyto) |
1. Porphyria cutanea tarda
2. Hepato erythropoetic porphyria |
1. Liver
2. Liver |
1. Dominant
2. Recessive |
1. Yes
2. Yes |
1. No
2. No |
| Coporphyrinogen I, III (CPG) |
CPG oxidase (mito) |
Coproporphyria |
Liver |
Dominant |
Yes |
Yes |
| Protoporphyrinogen IX |
PPG oxidase (mito) |
Variegate porphyria | Liver |
Dominant |
Yes |
Yes |
| Protoporphyrin IX |
Ferrochetalase (mito) |
Erythropoetic protoporphyria |
Bone marrow |
Dominant |
Yes |
No |
| Heme |
- |
- |
- |
- |
- |
- |
Sources:
- A. Kappas et al., 1995, pp 2103-2159 in The Metabolic and Molecular Bases of Inherited Disease vol. 2, (C.R. Scriver et al., eds.), McGraw Hill.
- M.J Warren et al., 1996, TIBS 21, 229-34.
