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DHCR24 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

DHCR24 gene

The DHCR24 gene provides instructions for making the enzyme 24-dehydrocholesterol reductase, which is critical for the final steps of cholesterol production in the body.

Normal Function

The DHCR24 gene provides instructions for making an enzyme called 24-dehydrocholesterol reductase. This enzyme is involved in multiple pathways that produce cholesterol. Cholesterol is a waxy, fat-like substance that can be obtained from foods that come from animals (particularly egg yolks, meat, poultry, fish, and dairy products). It can also be produced in various tissues in the body. For example, the brain cannot access the cholesterol that comes from food, so brain cells must produce their own. In one pathway, 24-dehydrocholesterol reductase is involved in the final step of cholesterol production (synthesis), converting the fat desmosterol into cholesterol. In a different pathway, 24-dehydrocholesterol reductase converts the fat lanosterol into another fat called 24,25-dihydrolanosterol. The end product of both of these pathways is cholesterol.

Cholesterol is necessary for normal embryonic development and has important functions both before and after birth. Cholesterol is an important component of cell membranes and the fatty protective covering that insulates nerves (myelin). Cholesterol also attaches (binds) to certain proteins to turn on (activate) the hedgehog signaling pathway, which is critical for normal development of many parts of the body before birth. Additionally, cholesterol plays a role in the production of certain hormones and digestive acids.

Health Conditions Related to Genetic Changes

Desmosterolosis

At least seven mutations in the DHCR24 gene have been found to cause desmosterolosis. Desmosterolosis is a condition characterized by neurological problems, such as brain abnormalities and developmental delay, and can also include other signs and symptoms. The mutations that cause this condition change single protein building blocks (amino acids) in the 24-dehydrocholesterol reductase enzyme. As a result, enzyme activity is reduced and cholesterol production is decreased. Because the brain relies solely on cellular production for cholesterol, it is most severely affected. Without adequate cholesterol, cell membranes are not formed properly and nerve cells are not protected by myelin, leading to the death of these cells. In addition, a decrease in cholesterol production has more severe effects before birth than during other periods of development because of the rapid increase in cell number that takes place. Disruption of normal cell formation before birth likely accounts for the additional developmental abnormalities of desmosterolosis.

Other Names for This Gene

  • 3 beta-hydroxysterol delta 24-reductase
  • 3-beta-hydroxysterol delta-24-reductase
  • DCE
  • delta(24)-sterol reductase
  • delta(24)-sterol reductase precursor
  • desmosterol-to-cholesterol enzyme
  • diminuto/dwarf1 homolog
  • KIAA0018
  • Nbla03646
  • seladin 1
  • seladin-1
  • SELADIN1
  • selective AD indicator 1

Frequently Asked Questions

Desmosterolosis is diagnosed by measuring sterol profiles in plasma, tissue, or cultured skin fibroblasts using gas chromatography-mass spectrometry (GC-MS). Affected individuals show markedly elevated levels of the cholesterol precursor desmosterol alongside low or low-normal total cholesterol concentrations. The biochemical diagnosis is definitively confirmed through molecular genetic testing that identifies biallelic pathogenic variants in the DHCR24 gene.
Infants born with desmosterolosis present with severe neurodevelopmental deficits, microcephaly or macrocephaly, structural brain malformations (such as agenesis of the corpus callosum and ventriculomegaly), characteristic facial dysmorphisms (cleft palate, micrognathia, and low-set ears), short limbs (rhizomelia), clubfeet, and occasionally ambiguous genitalia or congenital heart defects.
While dietary cholesterol supplementation can assist with systemic, non-neurological tissues, it cannot cross the blood-brain barrier in meaningful amounts. Because the central nervous system relies almost exclusively on local, endogenous cholesterol synthesis by glial and neuronal cells, defective 24-dehydrocholesterol reductase in the brain prevents proper myelination and development regardless of how much cholesterol is provided in the diet.
Desmosterolosis is inherited in an autosomal recessive manner. Both biological parents of an affected child are typically asymptomatic carriers who each harbor one mutated DHCR24 allele. With each pregnancy, carrier parents face a 25% risk of having an affected child, a 50% chance of having an asymptomatic carrier child, and a 25% chance of having an unaffected child who does not carry the mutation. Genetic counseling and prenatal or preimplantation testing options are recommended for affected families.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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