The genetic problem phenylketonuria (PKU) is the inability to metabolize phenylalanine on account of a lack of the enzyme phenylalanine hydroxylase. People with this disorder are generally known as "phenylketonurics" and will have to regulate their ingestion of phenylalanine. Even though it is not authorized as medication in many nations https://landenrqolh.illawiki.com/1141301/bisoprolol_fumarate_no_further_a_mystery