Which inherited disorder affects rod photoreceptors and impairs night vision and may involve rhodopsin gene mutations?

Which inherited disorder affects rod photoreceptors and impairs night vision and may involve rhodopsin gene mutations?

• A. Bradyopsia
• B. Retinitis pigmentosa (RP)
• C. Congenital stationary night blindness (CSNB)
• D. Cone dystrophy

Answer: (C)

Night vision relies on the rod pathway carrying signals from photoreceptors to the next retinal neurons. When the problem lies in this signaling from rods rather than in the rods themselves degenerating, you get a form of inherited night blindness that is present from birth and does not progress—congenital stationary night blindness. This condition fits the stem because it centers on rod pathway dysfunction causing impaired night vision, and some genetic forms can involve mutations in rod-related genes such as rhodopsin, which explains the mention of rhodopsin gene mutations. In contrast, other conditions either mainly affect the photoreceptors themselves in a progressive way (like retinitis pigmentosa), or primarily involve cones (cone dystrophy), or alter processing dynamics (bradyopsia), making them distinct from this stationary rod-pathway issue.

Night vision relies on the rod pathway carrying signals from photoreceptors to the next retinal neurons. When the problem lies in this signaling from rods rather than in the rods themselves degenerating, you get a form of inherited night blindness that is present from birth and does not progress—congenital stationary night blindness. This condition fits the stem because it centers on rod pathway dysfunction causing impaired night vision, and some genetic forms can involve mutations in rod-related genes such as rhodopsin, which explains the mention of rhodopsin gene mutations. In contrast, other conditions either mainly affect the photoreceptors themselves in a progressive way (like retinitis pigmentosa), or primarily involve cones (cone dystrophy), or alter processing dynamics (bradyopsia), making them distinct from this stationary rod-pathway issue.