Question

What shall be the ratio of heterozygous, homozygous and colourblind hemizygous in offsprings of a colour blind husband & a carrier wife?

• A. $1:1:2$
• B. $1:1:1$
• C. $2:1:1$
• D. $1:2:1$

Answer 1

The correct option is A $1:1:2$

Gametes	22A+X	22A+X'
22A+X'	22AA+XX'- Carrier female offspring	22A+X'X'- Diseased female offspring
22A+Y	22AA+XY- Normal male offspring	22AA+X'Y- Diseased male offspring

Colour blindness is an X-linked recessive disorder.

So if the father is colourblind then genotype should be: 22AA+X'Y

For the mother to be carrier the genotype should be: 22AA+ XX'

(where X is dominant over X', and X' is responsible for colourblindness)

The cross between the parents can be depicted as:

So, the ratio of heterozygous, homozygous and colour blind hemizygous offsprings are 1:1:2.

So, the correct answer is 'Option A- 1:1:2'.