Genetics
posted by Keira .
Phenylketonuria is a metabolic disease of humans that results from an autosomal recessive gene. If the frequency of phenylketonurics in the population is 9/10,000, what is the probability that two normal individuals will produce a diseased child?

(9/10,000)? Is that the frequency of a phenyketonuria child, or the frequency of the recessive gene. The problem statement is uncertain.
If the 9 tenthousandts is the frequency of phenylketonuria people, then that is the frequency two normal individuals will produce a diseased child.
If the 9 ten thousandths is the frequence of the recessive gene, then the frequency of children is the square of that. 
I think its the frequency of the gene this is a HardyWeignberg problem
Thanks!