Red colour blindness is called
**Core Concept**
Red colour blindness is a congenital condition characterized by the inability to perceive the colour red due to an abnormality in the long-wavelength cone cells in the retina. This condition is inherited in an X-linked recessive pattern.
**Why the Correct Answer is Right**
The correct answer is protanopia. Protanopia is caused by mutations in the OPN1LW gene, which codes for the long-wavelength cone pigment responsible for red colour perception. Individuals with protanopia have difficulty distinguishing between red and green colours, and often perceive red as a shade of green or yellow. This is because the remaining cone cells are sensitive to longer wavelengths, but not as sensitive as the normal red-sensitive cones.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify a particular type of colour blindness. There are several types of colour blindness, including protanopia, deuteranopia, and tritanopia.
**Option B:** This option is incorrect because it is not a specific type of colour blindness. Deuteranopia is a type of colour blindness, but it is associated with difficulty perceiving green, not red.
**Option C:** This option is incorrect because it refers to a type of colour vision deficiency, but it is not specific to red colour blindness.
**Option D:** This option is incorrect because it is not a recognized type of colour blindness.
**Clinical Pearl / High-Yield Fact**
It's worth noting that colour blindness is more common in males than females due to the X-linked recessive inheritance pattern. Females can be carriers of the mutated gene, but they are less likely to be affected due to having two X chromosomes.
**Correct Answer:** C. Protanopia