Leber Congenital Amaurosis (LCA)

The first, most meaningful, and strongest bond a newborn baby establishes with their parents is undoubtedly visual contact. A baby’s response to the light, colors, and faces in their environment is one of the most fundamental indicators of healthy development. However, hereditary genetic factors can sometimes disrupt this miraculous process. Leber Congenital Amaurosis (LCA), which manifests at birth or within the first few months of life and results in severe vision loss or total blindness, is a challenging genetic retinal disease. Nevertheless, it is also the field where medicine has achieved its greatest revolutions in recent years.

What is Leber Congenital Amaurosis (LCA)?

First described in 1869 by Dr. Theodor Leber, Leber Congenital Amaurosis (LCA) is one of the most common genetic causes of congenital blindness in childhood. It is a group of severe and early-onset hereditary retinal dystrophies that cause the retina (the light-sensitive nerve layer at the back of the eye) to fail in its function from birth.

In a healthy eye, there are millions of photoreceptor cells called rods and cones on the retina that perceive light and colors. In babies with LCA, due to a genetic coding error, these light-sensing cells either develop structurally incorrectly or degenerate rapidly shortly after birth. This prevents the eye from transmitting light signals to the brain, depriving the baby of the ability to perceive the outside world visually. Although the disease can have a degenerative (progressive) character, the greatest extent of the damage has usually already occurred within the first months of life.

Causes and Genetic Infrastructure

Leber Congenital Amaurosis is an entirely hereditary disease. As of today, mutations in at least 25 different genes critical for the healthy development and function of the retina have been identified as causes of LCA. The most common gene mutations include CEP290, CRB1, GUCY2D, and RPE65.

LCA is inherited in an Autosomal Recessive manner in almost all cases. This occurs as follows:

1. For a child to have LCA, they must inherit the faulty copy (mutation) of the same gene from both the mother and the father.
2. Parents are usually "carriers," meaning they carry one healthy and one mutated gene and have no vision problems themselves. Most families are completely unaware they are carriers until their child is diagnosed.
3. For every pregnancy of two carrier parents, there is a 25% chance the child will be born with LCA.
4. Because the cause is genetic, a definitive diagnosis requires DNA analysis in a laboratory environment.

What are the Symptoms of LCA?

LCA usually manifests within the first few months of life with striking clinical signs. Parents and pediatricians may quickly notice abnormalities in the baby’s visual development. The most characteristic symptoms include:

1. Severe Congenital Vision Loss: The most basic sign is the baby not following objects, not focusing on the parents' faces, and remaining unresponsive to environmental visual stimuli.
2. Nystagmus (Involuntary Eye Shaking): Continuous, uncontrollable, and rhythmic shaking movements of the eyes. Since the brain cannot receive a clear image, the eyes move constantly in search of a "focus."
3. Oculo-Digital Sign (Franceschetti's Sign): One of the most typical and distinguishing physical signs of LCA. The child constantly rubs their eyes with their fists or presses their fingers forcefully into the eyeball. This behavior is thought to mechanically stimulate the retina to send artificial flashes of light (phosphenes) to the brain. However, this constant pressure can lead to thinning of the cornea (keratoconus) later in life.
4. Extreme Light Sensitivity (Photophobia) or Unresponsiveness: Depending on the mutated gene, some babies may not react to light at all, while others feel intense discomfort in bright light.
5. Sluggish Pupil Reactions: The reflex of the pupils to constrict when exposed to light is very weak or non-existent.

Diagnosis and Genetic Mapping with Advanced Technology

Diagnosing congenital blindness requires a multidisciplinary approach. At Dr. Ayşe Öner’s clinic, we apply the world’s most advanced diagnostic protocols for our international patients:

1. Electroretinography (ERG): The undisputed gold standard for LCA diagnosis. It measures the electrical responses of the retina to light. In babies with LCA, no electrical activity can be recorded; the result appears as a "flat line" (extinguished ERG).
2. Genetic Testing and DNA Analysis: Identifying which gene is mutated is now a necessity for treatment planning. Our clinic works in integration with internationally accredited genetic laboratories to map the patient’s genetic profile.
3. Detailed Fundus Examination and OCT: The retinal structure is examined under anesthesia or with special pediatric devices (RetCam, Handheld OCT). While the fundus may look normal initially, pigment changes, vessel thinning, and macular degeneration appear with age.

Revolution in Treatment: Gene Therapy and Future Vision

The greatest revolution in hereditary eye diseases has occurred in Leber Congenital Amaurosis. While only supportive rehabilitation could be offered in the past, today, vision is being significantly restored in some types of LCA through gene therapies.

RPE65 Mutation and the Luxturna Revolution

If genetic testing confirms that the disease is caused by a mutation in the RPE65 gene (approximately 5-10% of LCA patients), the FDA and EMA-approved gene therapy drug Luxturna (Voretigene neparvovec) is utilized. Injected under the retina via microscopic surgery, this drug carries a healthy copy of the gene into the cells. Following treatment, patients' light sensitivity, night vision, and ability to move independently increase dramatically.

Ongoing Research (CRISPR) for Other Genes

For genes other than RPE65 (e.g., CEP290), promising clinical Phase studies regarding CRISPR-Cas9 gene-editing technology and special RNA therapies (Antisense Oligonucleotides) are ongoing worldwide. Dr. Ayşe Öner monitors these global developments in real-time to bridge the gap between these next-generation treatments and eligible patients.

Darkness does not have to be a genetic fate. To decode your child's genes and access the most advanced gene therapy horizons, contact our health experts immediately.