Multiple carboxylase deficiency

Multiple carboxylase deficiency (MCD) is a rare metabolic disorder that affects the body's ability to metabolize certain proteins and fats. It is characterized by a deficiency of the enzymes biotinidase and holocarboxylase synthetase, which are necessary for the body to use the vitamin biotin. This deficiency can lead to a variety of symptoms, including skin rash, hair loss, seizures, developmental delay, and potentially life-threatening complications such as metabolic acidosis and coma.

Symptoms and Signs

The symptoms of MCD can vary widely, but they typically begin in infancy or early childhood. They may include:

• Skin rash
• Hair loss
• Seizures
• Developmental delay
• Ataxia (lack of muscle control or coordination)
• Hypotonia (low muscle tone)
• Metabolic acidosis (a buildup of acid in the body)
• Coma

Causes

MCD is caused by mutations in the BTD gene, which provides instructions for making the enzyme biotinidase, or the HLCS gene, which provides instructions for making the enzyme holocarboxylase synthetase. These enzymes are necessary for the body to use the vitamin biotin. Without enough of these enzymes, the body cannot properly metabolize certain proteins and fats.

Diagnosis

Diagnosis of MCD is typically made through a combination of clinical examination, laboratory testing, and genetic testing. Laboratory tests may include blood and urine tests to check for elevated levels of certain substances that can indicate a problem with biotin metabolism. Genetic testing can confirm a diagnosis by identifying mutations in the BTD or HLCS genes.

Treatment

Treatment for MCD typically involves lifelong supplementation with biotin. This can help to replace the missing enzymes and allow the body to properly metabolize proteins and fats. In some cases, dietary modifications may also be necessary.

Prognosis

With early diagnosis and treatment, individuals with MCD can often lead normal, healthy lives. However, if left untreated, the condition can lead to serious, potentially life-threatening complications.

See also

• Biotinidase deficiency
• Holocarboxylase synthetase deficiency
• Metabolic disorder
• Inborn errors of metabolism

Multiple carboxylase deficiency Resources
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