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

HCCS gene

The HCCS gene provides instructions for producing an enzyme essential for mitochondrial energy production and the regulation of programmed cell death.

Normal Function

The HCCS gene carries instructions for producing an enzyme called holocytochrome c-type synthase. This enzyme is active in many tissues of the body and is found in the mitochondria, the energy-producing centers within cells.

Within the mitochondria, this enzyme helps produce a molecule called cytochrome c. Specifically, it is involved in a reaction that adds an iron-containing molecule called heme to make mature cytochrome c (also called holocytochrome c) from a precursor form called apocytochrome c.

Cytochrome c is involved in oxidative phosphorylation, the process by which mitochondria generate adenosine triphosphate (ATP), the cell's main energy source. It also plays a role in the self-destruction of cells, known as apoptosis.

Health Conditions Related to Genetic Changes

Microphthalmia with linear skin defects syndrome

Mutations or deletions involving the HCCS gene have been identified in individuals with microphthalmia with linear skin defects syndrome. These genetic changes result in a holocytochrome c-type synthase enzyme that cannot perform its function or prevent the production of the enzyme entirely.

The loss of this functional enzyme can damage cells by:

  • Impairing the ability to generate energy.
  • Preventing cells from undergoing apoptosis.
  • Causing cells to die via necrosis, which triggers inflammation and damages neighboring cells.

During early development, this spreading cell damage leads to the eye and skin abnormalities characteristic of the syndrome.

Other Names for This Gene

  • CCHL
  • CCHL_HUMAN
  • DKFZp779I1858
  • holocytochrome c synthase (cytochrome c heme-lyase)
  • MCOPS7

Frequently Asked Questions

Microphthalmia (small or absent eyes) is usually noted at birth, often accompanied by linear or streaky skin lesions along the arms, legs, or trunk. Parents may also notice eyelid abnormalities or reduced eye movement early on.
definitive diagnosis requires a DNA test, typically a targeted gene panel or whole-exome sequencing that includes HCCS. The test looks for pathogenic variants or deletions that disrupt the gene. A confirmatory test may involve a copy‑number analysis if a deletion is suspected.
HCCS mutations are inherited in an autosomal recessive pattern. If both parents carry one mutated copy, each pregnancy has a 25 % chance of being affected, a 50 % chance of being a carrier, and a 25 % chance of being unaffected. Genetic counseling is recommended before conception.
Management focuses on supportive care: ophthalmologic monitoring for vision development, dermatologic care for skin lesions, and early intervention services for developmental delays. There is no cure to replace the enzyme; treatment is symptom‑based and multidisciplinary.
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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