Phenylketonuria (PKU)

By: Johanna Wright

What is PKU?

PKU is a very rare disorder where a baby is born without the ability to break down a certain type of amino acid called phenylalanie. Also meaning they are missing an enzyme called phenylalanie hydroxylase, this is what is needed to break down that amino acid. The foods which contain most of the phenylalanie are protiens such as; meats and eggs.


People with PKU tend to have lighter skin, hair, and eyes when compared to their siblings. This is caused by the lack of phenylalanie they consume because phenylalanie plays a role on the body's production of melanin which controls pigment of hair, eyes, and skin. Other symptoms include:



-delayed mental and social skills

-head size significantly below normal



Knowing that PKU is a rare condition you'd think it is caused by a missing or extra chromosome or something. Really the only way to have a child with PKU is if it is carried throughout families meaning, BOTH parents must carry the defective/recessive gene otherwise the child will not be born with PKU. Knowing all of this it is somewhat inherited from families/parents. The only thing that occurs is again they are missing an enzyme which is essential to break down an amino acid called phenylalanie.

What types of people are more likely to have PKU?

As explained before PKU is very rare. It must be passed on through families and with both parents. It does not effect boys more than girls or girls more than boys. PKU can also affect adults or children also saying you must be born in this condition in order to have it in the first place.

Diagnosis and Treatment

Just to be sure within the first few weeks of a baby's life they are all tested for PKU. The doctor takes a little bit of blood and the baby must have had at least one protein meal before being tested. Treatment for those effected with PKU is possible. The only thing they can do is put the child on a strict diet of no protein (foods containing phenylalanie). This diet must be closely followed in order for the child to get better. It is best for one with PKU to do this the first years of life so hopefully their brain can develop better without the protein in their diet.