Why is the disease Phenylketonuria described as “relatively common”?

Question

I know 1 in 50 people carry the gene for this disease, but only 1 in 14000 people are born with it. Why is it then that the disease is described as “relatively common” given these frequencies?

Answer 1

Population-genetically speaking, any gene which is present at greater than 1% (1 in 100) is considered to be relatively common. The fact that it is recessive, and that there seems to be some selection against it (1 in 50 in heterozygotes should give 1 in 2500 in homozygotes. the fact that it only appears 1 in 14,000 means that the others may not make it to birth) makes the homozygote data skewed.

Answer 2

1 in 14000 means 430,000 people are afflicted, probably not common but also not rare

Answer 3

one in fourteen thousand? Thats a pretty "common percentage" verses one in six billion....