Question

A woman is heterozygous for a rare dominant autosomal genetic disease, Neurofibromatosis. She marries a normal man (homozygous recessive for Neurofibromatosis), who has Red-Green Color blindness, an X-linked recessive trait. They have children. If the woman is homozygous for normal vision, what is the chance they will have a daughter with color blindness?
A. 100%
B. 50%
C. 0%
D. 25%

Answer 1

Answer:

Option A

Explanation:

Given -

Man has X-linked recessive trait . Thus its genotype can be represented as

YX'

Woman has normal vision with homozygous genotype i.e "XX"

A cross is carried out between the above two parents thereby producing following offspring -

Y X’

X XY XX’

X XY XX’

Out of four offspring two are boy "XY" which do not have Red-Green Color blindness

While the two daughters "XX' " have Red-Green Color blindness

Thus, all the daughters produced have Red-Green Color blindness. Thus the chance of having a daughter with color blindness is 100 percent

Option A