Holocarboxylase Synthetase Deficiency

What is holocarboxylase synthetase deficiency?

Holocarboxylase synthetase deficiency is an inherited disorder in which the body is unable to use the vitamin biotin effectively. This disorder is classified as a multiple carboxylase deficiency, a group of disorders characterised by impaired activity of certain enzymes that depend on biotin.

The signs and symptoms of holocarboxylase synthetase deficiency typically appear within the first few months of life, but the age of onset varies. Affected infants often have difficulty feeding, breathing problems, a skin rash, hair loss (alopecia), and a lack of energy (lethargy). Immediate treatment and lifelong management (using biotin supplements) may prevent many of these complications. If left untreated, the disorder can lead to delayed development, seizures, and coma. These medical problems may be life-threatening in some cases.

How common is holocarboxylase synthetase deficiency?

This condition affects an estimated 1 in 87,000 people.

What genes are related to holocarboxylase synthetase deficiency?

Mutations in the HLCS gene cause holocarboxylase synthetase deficiency.

The HLCS gene makes an enzyme, holocarboxylase synthetase, that attaches biotin to other molecules. Biotin, a B vitamin, is found in foods such as liver, egg yolks, and milk. It is essential for the normal production and breakdown of proteins, fats, and carbohydrates in the body. Mutations in the HLCS gene reduce the activity of holocarboxylase synthetase, preventing cells from using biotin effectively and disrupting many cellular functions. These defects lead to the serious medical problems associated with holocarboxylase deficiency.

How do people inherit holocarboxylase synthetase deficiency?

This condition is inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered. Most often, the parents of an individual with an autosomal recessive disorder are carriers of one copy of the altered gene but do not show signs and symptoms of the disorder.

What other names do people use for holocarboxylase synthetase deficiency?

  • Early-Onset Biotin-Responsive Multiple Carboxylase Deficiency
  • Early-Onset Combined Carboxylase Deficiency
  • HLCS deficiency
  • Infantile Multiple Carboxylase Deficiency
  • Multiple Carboxylase Deficiency, Neonatal Form

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