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CLN3 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

CLN3 gene

The CLN3 gene provides instructions for making a protein found in tissues throughout the body, with mutations linked to CLN3 disease and isolated retinal degeneration.

Normal Function

The CLN3 gene provides instructions for making a protein that is found in tissues throughout the body, yet its function is unclear. The CLN3 protein is found in many compartments within cells, but its role in lysosomes—cellular compartments that digest and recycle molecules—is most well-studied. The protein spans the membrane surrounding lysosomes, helping to facilitate communication between the organelle and the rest of the cell.

Studies have associated the CLN3 protein with many cellular processes, including:

  • Recycling of worn-out cell parts and unneeded proteins (autophagy)
  • Maintenance of the relative acidity (pH) of lysosomes
  • Movement of molecules from the cell surface into the cell (endocytosis)
  • Transportation (trafficking) of proteins to where they are needed in the cell
  • Self-destruction of cells (apoptosis)
  • Cell growth and division (proliferation)
  • Maintenance of the body's water balance (osmoregulation)

It is uncertain which of these varied functions is the primary role of the CLN3 protein, or if these processes represent downstream effects.

Health Conditions Related to Genetic Changes

CLN3 disease

More than 65 mutations in the CLN3 gene have been found to cause CLN3 disease, an inherited disorder that begins in childhood and primarily affects the nervous system. Symptoms include worsening vision impairment, intellectual disability, movement problems, speech difficulties, and seizures.

The most common mutation, found in the vast majority of cases, is a 1 kilobase (kb) deletion that removes a piece of the gene and leads to the production of an abnormally short protein. This abnormal protein is broken down or interferes with normal cellular processes. CLN3 disease is characterized by the accumulation of proteins and other substances in lysosomes, particularly in nerve cells, leading to cell damage and death.

Other disorders

Mutations in the CLN3 gene can also cause CLN3-associated isolated retinal degeneration, which involves vision impairment without the neurological features of CLN3 disease. This condition is caused by a breakdown of light-sensitive tissue at the back of the eye (retinal degeneration), leading to decreased sharpness of vision and increased sensitivity to light (photophobia).

  • Early-onset form: Begins in late childhood or adolescence.
  • Late-onset form: Begins in early to mid-adulthood.

Research suggests these mutations are less severe than those causing CLN3 disease, resulting in a partially functional protein.

Frequently Asked Questions

Early signs of CLN3 disease often begin in childhood, typically between ages 4 and 8. Parents might first notice subtle changes in vision, such as difficulty seeing in dim light or bumping into objects, which can progress to significant vision loss. Other early indicators can include clumsiness, changes in speech, learning difficulties, or new-onset seizures. If you observe a combination of these symptoms, especially progressive vision problems or neurological changes, it's important to consult a pediatrician or a neurologist for evaluation.
Children with CLN3 disease require comprehensive, multidisciplinary care due to the progressive nature of the condition. This typically involves regular visits with neurologists, ophthalmologists, and developmental specialists. Support services may include physical therapy, occupational therapy, speech therapy, and educational support to address intellectual and motor skill decline. Seizure management with anti-epileptic medications is often necessary. As the disease progresses, palliative care focused on comfort and quality of life becomes increasingly important.
CLN3 disease is inherited in an autosomal recessive pattern. This means that a child must inherit two copies of a mutated CLN3 gene (one from each parent) to develop the condition. Parents who each carry one copy of the mutated gene are typically healthy and unaware they are carriers. For each pregnancy, if both parents are carriers, there is a 25% chance their child will have CLN3 disease, a 50% chance the child will be a carrier, and a 25% chance the child will not have the disease and not be a carrier. Genetic counseling can help families understand these risks.
Yes, the diagnosis of CLN3 disease is primarily confirmed through genetic testing. A blood test can analyze the CLN3 gene for mutations. The most common mutation, a 1 kilobase (kb) deletion, accounts for the vast majority of cases and is specifically looked for. Other less common mutations can also be identified through full gene sequencing. Clinical evaluation, including neurological assessments, vision tests, and sometimes an MRI of the brain, can support the diagnosis but genetic testing is definitive.
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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