Cytochrome b5 deficiency

Cytochrome b5 deficiency is a rare, inherited metabolic disorder characterized by a deficiency of the enzyme Cytochrome b5 reductase. This enzyme is involved in the electron transport chain, a series of reactions that produce energy in the body's cells.

Symptoms

The symptoms of Cytochrome b5 deficiency can vary greatly from person to person. Some individuals may experience no symptoms, while others may have severe symptoms. Common symptoms include methemoglobinemia, a condition characterized by an abnormally high level of methemoglobin (a form of hemoglobin) in the blood. This can lead to cyanosis, a bluish discoloration of the skin, lips, and nail beds. Other symptoms may include fatigue, shortness of breath, and headache.

Causes

Cytochrome b5 deficiency is caused by mutations in the CYB5R3 gene. This gene provides instructions for making the enzyme cytochrome b5 reductase. Mutations in the CYB5R3 gene reduce or eliminate the activity of this enzyme, leading to the symptoms of cytochrome b5 deficiency.

Diagnosis

Diagnosis of Cytochrome b5 deficiency is based on the symptoms, clinical examination, and confirmed by laboratory testing. This testing may include measuring the levels of methemoglobin in the blood and genetic testing to identify mutations in the CYB5R3 gene.

Treatment

Treatment for Cytochrome b5 deficiency is aimed at managing the symptoms. This may include oxygen therapy for individuals with severe cyanosis and medications to reduce the levels of methemoglobin in the blood.

See also

• Methemoglobinemia
• Cytochrome b5 reductase
• CYB5R3

References

Cytochrome b5 deficiency Resources
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