What is the name of the disease characterized by the absence of the iris leading to visual impairment?

• A. Aniridia
• B. Achondroplasia
• C. Marfan Syndrome
• D. Huntington Disease

Answer: (A)

Aniridia is the condition characterized by the absence of the iris, which can significantly affect vision. The iris is the colored part of the eye that helps regulate the amount of light entering the pupil. Without it, individuals may experience visual impairments due to light sensitivity, inability to focus properly, and other associated ocular issues. Aniridia is commonly linked to genetic mutations, particularly in the PAX6 gene, which is crucial for eye development.

In contrast, the other diseases listed have different primary characteristics. Achondroplasia is a form of short-limbed dwarfism caused by mutations in the FGFR3 gene impacting bone growth. Marfan Syndrome is a connective tissue disorder that affects multiple systems in the body, including the cardiovascular and skeletal systems, but does not specifically involve the iris or vision. Huntington Disease is a neurodegenerative disorder that leads to cognitive decline and motor dysfunction, without a direct relation to the iris or visual impairment issues. Hence, aniridia is distinctly identified by the absence of the iris and its associated visual challenges.