Question

Incontinetia pigmenti is an x-linked dominant condition. homozygotes and hemizygotes die in utero. in infancy ip causes blistering of parts of the skin, and patchy altered pigmentation later. a woman with ip has a newborn child. what is the chance that newborn will be an unaffected girl?

Answer 1

Answer:

Option A

Explanation:

Complete Question

Incontinetia pigmenti is an X-linked dominant condition. Homozygotes and hemizygotes die in utero. In infancy IP causes blistering of parts of the skin, and patchy altered pigmentation later. A woman with IP has a newborn child. What is the chance that newborn will be an unaffected girl?

a. 1/4

b. 1/3

c. 1/2

d. 2/3

e. 3/4

f. Impossible to know without more information.

Solution

As we know that an X-linked dominant inheritance is a kind of genetic condition in which X linked mutant is a dominant trait. Thus, even if one copy of X chromosome is present, the offspring would be diseased individual.  

Here , Given

Woman has ip, hence in order to have unaffected girl child she must mate a normal man

Genotype of woman would be XX'

Genotype of man would be YX

XX' * YX

XY, XX, X'Y. X'X

Two daughter and two son will be produce.

Out of the two daughters one is diseased and another one is normal.

Thus, the chance that newborn will be an unaffected girl is

$\frac{1}{4}$

Thus, option A is correct