Question

Suppose color blindness is a X linked trait in humans. It is also recessive. A phenotypically normal woman has a father with color blindness. This woman marries a man with normal vision. What is the chance of their children being color blind? What is the chance of their daughters being color blind?

Answer 1

Ans: Woman genotype must be- X⁺X^c

Where X⁺ represents normal allele which she must have got from her mother.

and, X^c represents color blind allele which she must have got from her father.

If this woman marries a man with normal vision- X⁺Y

	X+	Y
X+	X+X+ (Female-normal vision)	X+Y (Male-normal vision)
Xc	X+Xc (Female-normal vision)	XcY (Male-color blind vision)

• Chance of their children being color blind- 1/4
• Chance of their daughter being color blind- Nil (As color blind gene is recessive).