Red green colour blindness is an example of ............. genetic disorder.
MH SET - 2021, SET Exam - 2021,
Answer: A
Red green colour blindness is an X-linked recessive disorder.
The genes for the red and green cone opsins lie on the X chromosome. A male has one X, so a single defective allele makes him colour blind; a female needs two copies and is usually an unaffected carrier. That is why about 8% of men of European descent but far fewer women are affected, and why the trait passes from a carrier mother to half her sons.
An X-linked dominant trait would appear in every daughter of an affected father, which is not seen. Y-linked traits pass only from father to son, and there are no colour vision genes on the Y.
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