Being diagnosed with PKU is kind of like winning the lottery honestly. Medicinenet.com states, "The approximate incident rate for PKU (lol, incident) in the US is 0.01%." Depending on where you live, the number is anywhere from 1 in 15,000 to 1 in 20, 000. Some countries have lots of cases, and some countries have very little cases. Check out this image outlining different cases throughout the world:
Why is it higher in some places than others? No idea. I am no scientist. But how do you actually get PKU? A lot of people ask me if anyone in my family has PKU, and the answer is NOPE! JUST ME! That's because it's genetic, not hereditary. Let me explain:
In order for a someone to have PKU, both the mom and the dad have to have the gene that carries the disease. Basically the instructions for breaking down protein have to be missing in both people in order for the child to not know how to do it (to put it simply). "PKU is an inherited condition caused by a defect in the PAH gene. The PAH gene helps create phenylalanine hydroxylase, the enzyme responsible for breaking down phenylalanine." But why is it so rare?
It's rare because even if both people are missing the gene, it's' STILL a 1 in 4 chance that the child will get PKU. That's why I say I won the lottery, because it's so. freaking. rare.
Now you could say "Hey Sam, on the chart above, it says that Sicily has the highest chances of getting PKU and you're Italian. Does that have anything to do with it?" The answer is maybe! However it's more probable that I have it because people in European countries married and had kids with their cousins, which messes with their genetic makeup (my grandparents are cousins, what's it to ya?)
You can actually take a test before you have children to see if you're a carrier of the gene, and you can get your partner to take it as well. A lot of people are very adamant on getting this test done, and making sure they know the outcome of their child. Personally, I don't really care to know if my partner is a carrier, because even if he is, it's still a 1 in 4 chance of my child having PKU so you'll never really know. Also, even if my child has PKU, that's not going to stop me from having a child and I will love them all the same. So I personally, don't feel a need to take the test.
This is a lot of information so I'm going to stop there! But as I've said before, if you have questions, please feel free to comment or contact me!