Summary about Disease
Leber Congenital Amaurosis (LCA) is a rare, inherited eye disorder that causes severe vision loss beginning in infancy or early childhood. It is characterized by nystagmus (involuntary rapid eye movements), extreme light sensitivity (photophobia), and sluggish or absent pupillary responses. LCA is one of the most common causes of congenital blindness or severe visual impairment in infants and young children.
Symptoms
Severe vision loss from birth or early infancy
Nystagmus (rapid, involuntary eye movements)
Photophobia (extreme sensitivity to light)
Sluggish or absent pupillary responses to light
Eye poking or rubbing (oculo-digital sign)
Cataracts may develop later in life in some forms of LCA
Strabismus (misalignment of the eyes) can occur
Causes
LCA is caused by genetic mutations in various genes involved in the function of the retina (the light-sensitive tissue at the back of the eye). It is an autosomal recessive disorder, meaning that an affected individual must inherit two copies of the mutated gene (one from each parent) to develop the condition. If both parents are carriers (each having one copy of the mutated gene and one normal copy), there's a 25% chance with each pregnancy that the child will inherit both mutated genes and have LCA. Several genes are known to cause LCA; mutations in GUCY2D, *CEP290*, *CRB1*, *RPE65* and *AIPL1* are the most common.
Medicine Used
Gene Therapy (Luxturna): For LCA caused by mutations in the RPE65* gene, gene therapy (voretigene neparvovec-rzyl) is approved. This involves injecting a working copy of the *RPE65* gene into the retinal cells to improve vision.
Corrective lenses: Glasses or contact lenses to address refractive errors.
Low-vision aids: Devices like magnifiers or specialized software to maximize remaining vision.
Supportive Therapies: No medication other than gene therapy exists to treat LCA. Support to the patient is available through therapeutic specialists.
Is Communicable
No, Leber Congenital Amaurosis is NOT communicable. It is a genetic disorder, not an infectious disease. It cannot be spread from person to person.
Precautions
There are no precautions to prevent developing LCA, as it is a genetic condition. However, genetic counseling and testing are recommended for individuals with a family history of LCA or other inherited eye disorders. Precautions for those living with LCA:
Protect eyes from bright light: Use sunglasses and hats to minimize photophobia.
Ensure safe environments: Modify surroundings to reduce fall risks and other hazards.
Regular eye exams: Monitor for any changes in vision and other eye conditions.
How long does an outbreak last?
Since LCA is not an infectious disease, the concept of an "outbreak" is not applicable. It is a chronic condition that persists throughout the individual's lifetime. The vision loss is typically present from birth or early infancy and does not "resolve" in the same way an infection would.
How is it diagnosed?
Clinical Examination: Ophthalmological examination revealing severe vision loss, nystagmus, and abnormal pupillary responses.
Electroretinography (ERG): This test measures the electrical activity of the retina. In LCA, the ERG is usually severely reduced or absent.
Optical Coherence Tomography (OCT): To assess the retinal structure and identify any abnormalities.
Genetic Testing: Analyzing DNA to identify mutations in genes known to cause LCA. This is crucial for confirming the diagnosis and determining the specific type of LCA.
Visual Evoked Potential (VEP): Measures the electrical activity of the brain in response to visual stimulation, which may be abnormal in LCA.
Timeline of Symptoms
Birth/Early Infancy: Severe vision loss is typically present from birth or shortly after.
First Few Months: Nystagmus (involuntary eye movements) usually develops within the first few months of life.
Infancy/Early Childhood: Photophobia (light sensitivity) becomes apparent. Eye poking or rubbing (oculo-digital sign) is often observed.
Childhood/Adolescence: Vision remains severely impaired.
Later Life: Some individuals may develop cataracts or other secondary eye conditions.
Important Considerations
Genetic Counseling: Essential for families with a history of LCA, to understand the inheritance pattern and recurrence risk.
Early Intervention: Maximize visual potential and development through early intervention programs, including vision therapy, orientation and mobility training, and assistive devices.
Support Systems: Connecting with support groups and organizations for individuals with LCA and their families.
Regular Monitoring: Ongoing ophthalmological care to monitor for any changes in vision and manage any secondary eye conditions.
Research Advances: Staying informed about ongoing research and clinical trials for potential new treatments, including gene therapy, is crucial.