Question

Identify an X linked disorder?

• A. Color blindness
• B. Thalassemia
• C. Azoospermia
• D. Retinitis Pigmentosa

Answer 1

The Correct Option is A

Step 1: Sort each option by its mode and chromosome of inheritance. Step 2: The genes for the red and green cone photopigments lie on the $X$ chromosome, so red-green colour blindness is transmitted in an X-linked recessive pattern and shows male preponderance. Step 3: Thalassemia is autosomal recessive (alpha and beta globin genes on chromosomes 16 and 11), so it is not X-linked. Step 4: The remaining two, azoospermia and retinitis pigmentosa as listed here, are tied to the Y chromosome, leaving colour blindness as the sole X-linked condition.\[\boxed{\text{Colour blindness}}\]