| Disease ID | Source | Name | Description |
| 176200 | OMIM | Variegate porphyria (VP) | A form of porphyria. Porphyrias are inherited defects in the biosynthesis of heme, resulting in the accumulation and increased excretion of porphyrins or porphyrin precursors. They are classified as erythropoietic or hepatic, depending on whether the enzyme deficiency occurs in red blood cells or in the liver. Variegate porphyria is the most common form of porphyria in South Africa. It is characterized by skin hyperpigmentation and hypertrichosis, abdominal pain, tachycardia, hypertension and neuromuscular disturbances. High fecal levels of protoporphyrin and coproporphyrin, increased urine uroporphyrins and iron overload are typical markers of the disease. The disease is caused by variants affecting the gene represented in this entry. Mutations leading to severe PPOX deficiency cause the rare homozygous variant form of VP. Missense mutations that preserve 10%-25% of wild-type activity may not cause clinically overt VP in heterozygotes (PubMed:9811936). Mutations with intermediate effect on catalytic activity may cause VP, but with a low clinical penetrance (PubMed:10486317). |