SNP Shot: Genomic Insights

Age-related macular degeneration (AMD) is a primary cause of vision impairment in older adults in developed nations. While subtle visual changes may start as early as the forties or fifties, significant distortion and loss of central vision usually become apparent in the sixties or seventies and tend to worsen with age.

AMD primarily impacts central vision, which is essential for tasks requiring detailed focus, such as reading, driving, and facial recognition. The vision loss associated with AMD stems from the progressive breakdown of light-sensitive cells within the retina, the eye's light-detecting tissue. Specifically, AMD targets the macula, a small area near the center of the retina responsible for central vision. Peripheral and night vision are typically preserved, although early symptoms often include impaired dark adaptation and reduced vision in dim lighting (scotopic vision).

Scientists have identified two main types of AMD: dry and wet. Dry AMD is far more prevalent, accounting for 85-90% of cases. It involves the accumulation of drusen, yellowish deposits beneath the retina, leading to a gradual decline in vision. The most advanced stage of dry AMD is geographic atrophy, where areas of the macula deteriorate, resulting in significant vision loss. Dry AMD commonly affects both eyes, although vision loss may appear in one eye first.

In approximately 10-15% of individuals, dry AMD progresses to wet AMD. Wet AMD is defined by the growth of abnormal and delicate blood vessels beneath the macula. These vessels leak blood and fluid, damaging the macula and causing blurred and distorted central vision. Wet AMD is linked to rapid and severe vision loss.

Inheritance:

While AMD doesn't typically follow a straightforward inheritance pattern, it does seem to have a familial component in some instances. It's estimated that 15-20% of individuals with AMD have at least one close relative (e.g., a sibling or parent) who also has the condition.