FECH

The FECH gene provides instructions for the production of an enzyme called ferrochelatase. This enzyme is the eighth and final enzyme involved in the production of heme, the iron-containing part of hemoglobin. Hemoglobin is the oxygen-carrying protein in red blood cells. Each step in heme production is controlled by a different enzyme, each of which is produced from a single gene. To form heme, ferrochelatase inserts an iron atom into the center of protoporphyrin IX (the product of the seventh step in the heme production pathway). This reaction occurs within the cell's energy-producing structures (mitochondria). The heme molecule is incorporated into hemoglobin and packaged into red blood cells, or it is used in the liver for the production of certain liver enzymes.

porphyria - caused by mutations in the FECH gene

More than 80 different mutations in the FECH gene have been identified in individuals with a form of porphyria called erythropoietic protoporphyria. These mutations greatly reduce the activity of ferrochelatase when they occur in one of the two copies of the FECH gene in each cell. To show signs and symptoms of the disorder, however, a person must also have a particular version of the other copy of the gene. This variant gene, called a low-expression allele, reduces enzyme activity even further. Low levels of enzyme activity allow protoporphyrin (a byproduct of heme production) to build up in the body. High levels of protoporphyrin in the skin cause sun sensitivity characteristic of erythropoietic protoporphyria, and increased levels of this substance in the liver can result in liver damage.