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MT-ND4L gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

MT-ND4L gene

The MT-ND4L gene encodes a subunit of a critical mitochondrial enzyme complex, and mutations in this gene are linked to Leber hereditary optic neuropathy.

Normal Function

The MT-ND4L gene provides instructions for making a protein called NADH dehydrogenase 4L. This protein is part of a large enzyme complex known as complex I, which is active in mitochondria. Mitochondria are structures within cells that convert the energy from food into a form that cells can use through a process called oxidative phosphorylation, which uses oxygen and simple sugars to create adenosine triphosphate (ATP), the cell's main energy source.

Complex I is one of several enzyme complexes necessary for oxidative phosphorylation. Within mitochondria, these complexes are embedded in a tightly folded, specialized membrane called the inner mitochondrial membrane. During oxidative phosphorylation, mitochondrial enzyme complexes carry out chemical reactions that drive the production of ATP. Specifically, they create an unequal electrical charge on either side of the inner mitochondrial membrane through a step-by-step transfer of negatively charged particles called electrons. This difference in electrical charge provides the energy for ATP production.

Complex I is responsible for the first step in the electron transport process, the transfer of electrons from a molecule called NADH to another molecule called ubiquinone. Electrons are then passed from ubiquinone through several other enzyme complexes to provide energy for the generation of ATP.

Health Conditions Related to Genetic Changes

Leber hereditary optic neuropathy

A mutation in the MT-ND4L gene has been identified in several families with Leber hereditary optic neuropathy. This mutation, which can be written as T10663C or Val65Ala, changes a single protein building block (amino acid) in the NADH dehydrogenase 4L protein. Specifically, it replaces the amino acid valine with the amino acid alanine at protein position 65.

Researchers have not determined how a mutation in the MT-ND4L gene leads to the vision loss characteristic of Leber hereditary optic neuropathy. This genetic change appears to disrupt the normal activity of complex I in the mitochondrial inner membrane, which may affect the production of ATP. It remains unclear why the effects of this mutation are limited to the nerve that relays visual information from the eye to the brain (the optic nerve). Additional genetic and environmental factors likely contribute to the features of this condition.

Frequently Asked Questions

LHON is inherited in a mitochondrial (maternal) pattern, meaning only the mitochondria from the mother are passed on. If you carry the mutation, every child you have will inherit it, but only about 50% of those children will develop vision loss.
mutation in MT‑ND4L can cause Leber hereditary optic neuropathy (LHON), a genetic eye disease that often leads to sudden vision loss in one or both eyes, usually in young adults. The mutation disrupts the normal function of complex I in mitochondria, reducing the energy available for retinal cells and making them vulnerable to damage.
While no cure exists, some studies suggest that avoiding smoking, limiting alcohol, and ensuring adequate vitamin B12 and coenzyme Q10 levels may reduce the risk of progression. However, these measures are supportive and not guaranteed to prevent vision loss.
Current options include idebenone (a vitamin B3 derivative) and supportive therapies such as low‑vision aids. Early intervention may improve outcomes, but many patients experience permanent vision loss. Consult a neuro‑ophthalmologist for individualized care.
Typical early signs include a sudden, painless loss of central vision, a central scotoma (a dark spot in the center of vision), or blurred vision that worsens over days to weeks. If you notice any of these, seek ophthalmology care promptly.
Vision loss in LHON is usually irreversible; however, some patients experience partial spontaneous recovery within months. Long‑term prognosis depends on the severity of the initial loss and the presence of other mitochondrial mutations. Regular follow‑up is essential.
Testing is done via a blood draw or cheek swab for DNA sequencing of the mitochondrial genome. A positive result confirms the presence of a pathogenic mutation; it does not predict the exact age or severity of vision loss, but it indicates a higher risk and the need for regular eye monitoring.
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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