Question

If both your mother and father have PKU disease, what is true?

Question 4 options:

You will not have the disease because the dominant trait is expressed.


Since PKU is a recessive disease, your chances of having it are 100%.


Since both parents are homozygous, your chances of having it are 50%.


There is a 75% chance that you will be a carrier of the disease, but you will not show symptoms.

Answer 1

D. Is the most logical one although a 100% chance is always possible...

Answer 2

Answer:

Option B, Since PKU is a recessive disease, your chances of having it are 100%.

Explanation:

PKU is an autosomal recessive genes which means that any individual which has a disease must have two copy of mutated gene. In case if there is one copy of mutated gene then the parent will be called carrier parents and they do not have PKU disease.

Here both the parents have PKU diseases, thus they must be having two copy of mutated gene

Let the mutated gene in parents represented by

Male - X"Y''

Female - X''X''

The offsprings produced will be X''X'', X''Y'', X''X'', X''Y''

A cross between them will produce $100$% deceased offspring.