Download Mild Hyperphe i

2006
The Hospital for Sick Children PKU Program
The Child with Mild Hyperphe (Type III)
What is Mild Hyperphe? Mild Hyperphe is an inherited condition in which a
person's body is unable to properly utilize one part of protein found in food. This
condition causes mildly increased levels of phenylalanine in the blood. There are
no known problems associated with having Mild Hyperphe, so dietary treatment
is usually not required.
Hyperphe is an abbreviation of the medical term Hyperphenylalaninemia
(pronounced hyper-feenyl-al-a-nin-emia). This long medical term can be divided
into three parts and defined as follows:
1. Hyper: mean high
2. Phenylalanine: is an amino acid (a part of protein) found in the food
3. Emia: refers to the blood
Phenylalanine will be called PHE here.
To understand why the PHE is increased in the blood of a person with MPH, we
need to explain how the body handles proteins found in foods. Proteins are made
up of amino acids fastened in a chain. One of these amino acids is called PHE.
The body takes food protein, breaks it down into amino acids, and then uses the
amino acids to make all organs and tissues in the body. The process is as
follows: when protein is eaten, it is broken into the individual amino acids. The
amino acids are then absorbed from the intestinal tract into the blood. The amino
acids remaining after sufficient protein has been used are broken down further.
With Mild Hyperphe, the leftover PHE cannot be broken down. This causes
increased blood levels of PHE.
Are There Different Types of Hyperphe? Mild Hyperphe is one type of
Hyperphe. Each type is classified by the amount of PHE that can be measured in
the blood. In Mild Hyperphe, blood PHE is 140 – 600 μmol/L (micromoles per
liter) of blood. The child with Mild Hyperphe usually does not need a special diet.
However, a low PHE diet may be needed during pregnancy.
How is Mild Hyperphe Detected? A child with Mild Hyperphe is usually
discovered shortly after birth when a screening test is done in the newborn
nursery of the hospital by collecting blood from the baby's heel. If the results of
that test show a blood Mild Hyperphe level between 140-600 μmol/L, PBH is
diagnosed. The decision as to when to begin diet is made by the PKU treatment
center.
Treatment of Mild Hyperphe: Blood levels and diet are monitored periodically to
assure that the PHE level is maintained between 140 – 600 μmol/L. When your
child begins solid foods, a blood test should be obtained by your child's primary
care physician. As your child progresses to table foods, another blood test should
be performed. If the blood PHE is persistently greater than 600 μmol/L, a special
diet may need to be considered.
How Does One Get Mild Hyperphe? Genes are units of inheritance found in
body cells. Genes come in pairs in your cells with each parent contributing one
gene to the pair in each cell. A person who has one "normal" gene and one
altered Mild Hyperphe gene is called a carrier.
Figure I
Figure I represents you, the parents, both of you are carriers of the Mild
Hyperphe gene. The chance of two carriers marrying are one in 5,000.
Parents usually are not aware that they are carriers of the Hyperphe gene. The
carrier's "normal" gene tells the liver cells to make enough of the enzyme to
break down PHE. You carry the Mild Hyperphe gene but do not have PKU.
Figure II
Figure II represents your child's genetic make-up and the possible make-up of
the other children in your family. For each pregnancy there is a one in four
chance your child will have Mild Hyperphe. Your child inherited Mild Hyperphe
genes from both parents. Mild Hyperphe occurs once in 20,000 births.
Adapted from the Texas Department of State Health Services: Newborn Screening Case Management