KROK 1 Stomatology 2015 – Question 148 · KROK (Dentistry)
Phenylketonuria is a disease caused by a recessive gene that is localized in the autosome. The parents are heterozygous for this gene. They already have two sons with phenylketonuria and one healthy daughter. What is the probability that their fourth child will have the disease too?
- A. 0%
- B. 100%
- C. 50%
- D. 25%
- E. 75%
Hint
Write out the cross of two heterozygous carriers and remember that each pregnancy is an independent event.
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