FECH

The FECH gene produces an enzyme called ferrochelatase. This is the eighth and last enzyme in heme production. Heme is the portion of hemoglobin that carries oxygen in the blood from the lungs to the rest of the body. Each of the steps in heme production is controlled by a separate gene (see below). Ferrochelatase inserts an iron atom into the center of protoporphyrin IX (the product of the seventh step in the heme production pathway) in mitochondria to form heme. 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.

The following genes are part of the chemical pathway for making heme.

• ALAD:aminolevulinate, delta-, dehydratase
• ALAS1:aminolevulinate, delta-, synthase 1
• ALAS2:aminolevulinate, delta-, synthase 2 (sideroblastic/hypochromic anemia)
• CPOX:coproporphyrinogen oxidase (coproporphyria, harderoporphyria)
• FECH:ferrochelatase (protoporphyria)
• HMBS:hydroxymethylbilane synthase
• PPOX:protoporphyrinogen oxidase
• UROD:uroporphyrinogen decarboxylase
• UROS:uroporphyrinogen III synthase (congenital erythropoietic porphyria)

erythropoietic protoporphyria - caused by mutations in the FECH gene

At least 65 different mutations in the FECH gene have been identified in patients with erythropoietic protoporphyria. When present in one copy of the gene, these mutations greatly reduce the activity of the enzyme made by the gene. 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, 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, which causes the signs and symptoms of erythropoietic protoporphyria. For example, high levels of protoporphyrin in the skin cause sun sensitivity, and increased levels in the liver can result in liver damage.

18q21.3

The FECH gene is located on the long (q) arm of chromosome 18 at position 21.3.

See How do geneticists indicate the location of a gene? in the Handbook.

You and your healthcare professional may find the following resources about FECH helpful.

• Gene Tests - DNA tests ordered by healthcare professionals

You may also be interested in these resources, which are designed for genetics professionals and researchers.

• PubMed - Recent literature
• OMIM - Genetic disorder catalog
• Research Resources - Tools for researchers (3 links)

See How are genetic conditions and genes named? in the Handbook.

The Handbook provides basic information about genetics in clear language.

• What is DNA?
• What is a gene?
• How does a gene make a protein?
• How can gene mutations cause disorders?

These links provide additional genetics resources that may be useful.

• Genetics education
• Human Genome Project
• Resources for Genetic Researchers

allele ; anemia ; atom ; congenital ; enzyme ; gene ; heme ; hemoglobin ; iron ; mitochondria ; molecule ; mutation ; oxygen ; porphyrin ; protoheme ; red blood cell ; sensitivity ; sign ; sun sensitivity ; symptom ; synthetase

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.