A healthy couple, who recently emigrated from Eastern Europe, bring their 3-year-old son to the office for evaluation of an eczematous rash. On examination, the child also shows signs of intellectual disability and gait abnormality and has a musty body odor. What is the likelihood that this couple's next child will be affected with the same disease?

Question

A healthy couple, who recently emigrated from Eastern Europe, bring their 3-year-old son to the office for evaluation of an eczematous rash.  On examination, the child also shows signs of intellectual disability and gait abnormality and has a musty body odor.  What is the likelihood that this couple's next child will be affected with the same disease?

Quizplus · Accepted Answer

Eductional Objective: Intellectual disability, gait or posture abnormality, eczema, and a musty body odor in a toddler are signs of phenylketonuria (PKU).  Most infants with PKU are born to 2 heterozygous carrier parents.  The probability that heterozygous carrier parents will transmit an autosomal recessive disease such as PKU to a child is 1/4.

A Healthy Couple, Who Recently Emigrated from Eastern Europe, Bring