Erythropoietic porphyria

Erythropoietic porphyria is a type of porphyria associated with erythropoietic cells. In erythropoietic porphyrias, the enzyme deficiency occurs in the red blood cells.

There are three types:

X-linked sideroblastic anemia or "X-linked dominant erythropoietic protoporphyria", associated with ALAS2 (aminolevulinic acid synthase), has also been described. X-linked dominant erythropoietic protoporphyria (XDEPP) is caused by a gain of function mutation in the ALAS2 (5-aminolevulinate synthase) gene; the very first enzyme in the Heme biosynthetic pathway. The mutation is caused by a frameshift mutation caused by one of two deletions in the ALAS2 exon 11, either c. 1706-1709 delAGTG or c. 1699-1700 delAT. This alters the 19th and 20th residues of the C-terminal domain thereby altering the 2° structure of the enzyme. The delAT mutation only occurred in one family studied whereas the delAGTG mutation occurred in several genetically distinct families. The delAGTG causes a loss of an a-helix which is replaced by a ß-sheet.