Thread: nms review for step 1 genetics q

Test 1 question 43:

About 5% of individuals in a particular population are known to carry a recessive gene for poliodystrophy, an inherited disorder characterized by recurrent seizures and dementia with onset in early childhood. A 32-year old healthy woman who had a brother with this disorder seeks genetic counselling. The patient's husband, an only child, does not know if his family has a history of the disorder. What is the probability that the patient is a carrier of poliodystrophy?
a. 1/20
b. 1/10
c. 3/8
d. 2/3
e. 3/4

the answer is D. does anyone know how to approach the question?

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