SNP Shot: Genomic Insights

Gyrate atrophy, a genetic condition often affecting vision, involves the progressive degeneration of the choroid and retina. Specifically, cells in the retina, the eye's light-sensitive lining, and the adjacent choroid layer gradually deteriorate (atrophy). Individuals with gyrate atrophy typically develop nearsightedness (myopia), night blindness (difficulty seeing in dim light), and peripheral vision loss in childhood. This loss of peripheral vision progressively worsens, leading to tunnel vision. Cataracts, or clouding of the eye's lens, are also common. These combined changes ultimately result in blindness, often by age 50.

While vision loss is the primary symptom of gyrate atrophy, some individuals may experience additional effects. Rarely, newborns with the condition exhibit hyperammonemia, or elevated ammonia levels in the blood. This can manifest as poor feeding, vomiting, seizures, or even coma. Fortunately, neonatal hyperammonemia associated with gyrate atrophy usually resolves quickly with treatment and doesn't typically return after infancy.

Generally, gyrate atrophy does not impact intelligence. However, brain scans or other neurological tests may reveal abnormalities. In certain instances, mild to moderate intellectual disability can be associated with gyrate atrophy.

Gyrate atrophy can also affect the peripheral nervous system, the network of nerves connecting the brain and spinal cord to muscles and sensory cells. Some individuals may experience numbness, tingling, or pain in their hands or feet, while in others, these nerve abnormalities are only detectable through electrical nerve impulse testing.

In some individuals, gyrate atrophy leads to the breakdown of a specific type of muscle fiber (type II fibers). Though this muscle abnormality is often asymptomatic, it can occasionally cause mild muscle weakness.

Inheritance:

Gyrate atrophy is inherited in an autosomal recessive manner. This means that an affected individual inherits two copies of the mutated gene, one from each parent. The parents, who each carry one copy of the mutated gene, are usually unaffected carriers of the condition.