Gunther Disease - Causes

Causes

Gunther disease is caused by mutations in the gene that encodes the enzyme uroporphyrinogen III synthase (UROS), located at human chromosome 10q25.2-q26.3. The disorder is inherited in an autosomal recessive manner. This means the defective gene responsible for the disorder is located on an autosome, and two copies of the defective gene (one inherited from each parent) are required in order to be born with the disorder. The parents of an individual with an autosomal recessive disorder both carry one copy of the defective gene, but usually do not experience any signs or symptoms of the disorder. When there is a homozygous mutation it causes a uroporphyringen III synthase and uroporphyrinogen cosynthetase defect. When the enzyme uroporphyrinogen II synthase is reacting normally it results in the making of isomer III porphyrinogen, which is what is used to form heme. When isomer III porphyrinogen is not produced because of a poor production of uroporphyringen III synthase then isomer I porphyrinogen is made which will oxidize and give the skin a reddish tint.