The Disease

Chapter 3.: Consequences

Poison, destruction, but it is serious that!!

Yes, it is serious, but all depends on the age of the patients:

1. For the infants:
   birth at 6 years , the cells of the brain are in formation and thus sensitive to a toxic product like phenylalanine involving a progressive destruction of the brain and nervous cells .
   The very young phenylcetonuric children, untreated suffer from a severe backwardness who make serious handicapped people of them requiring a placement in specialized agency.
2. With pre-adolescence and adolescence:
   

   After the end of the fast development of the brain, the mode must be continued. The toxic effects of high rates of phenylalanine and its derived products are of two types:

   1. An effect slow , chronic, which appears especially during the active phase of the development of the brain (of the birth until adolescence). It results in the death of the nervous cells and the sheaths which surround nervous fibres
      This slow atrophy is unfortunately not reversible .
   2. An effect acute , reversible , is with a reduction in several neurotransmetteurs (substances secreted by the nervous cells, and who allow the various nervous cells to communicate between them).
      
      
      
      

      

      
      
      
      This reduction explains the changes of behavior and performance observed a few hours after a meal rich in proteins absorptive by a patient phenylcetonuric:
      

      • nervousness
      • fatigability
      • disorders of the concentration
      • difficulties of memorizing
      • difficulties of carrying out complex tasks

      The fall of the phenylalanine rates will allow a rapid standardization of the performances .

      The results of cerebral imageries practised by nuclear magnetic resonance showed anomalies of the white substance when a dietetic control in the long run of the disease was not satisfactory.
      These results are discussed , but while waiting for complementary studies, one should encourage the continuation of the processing lasting all the life .

      Finally the clean experiment of the adolescent and young patients adult who noticed that their performances were better when they were subjected to a strict control of the blood phenylalanine rates also contributed to the development of new recommendations.

3. Pregnancy:
   An extremely significant concept appeared quickly when the first treated patients were in age to have children.

   The maternal hyperphenylalaninemy exposes:

   • the pregnant women have a high risk of miscarriage
   • the children to be born have a high risk to have malformations such as: microcephali , problems of the development or congenital malformations in particular cardiac

   It appeared that a strict control of the maternal phenylalanine rates before the design was essential, not only in the phenylcetonuric mothers, but also in the hyperphenilalaninemic mothers, i.e. who have a rate moderately raised of phenylalanine which did not have, until the pregnancy, not required particular dietetic processing.

Much of people are reached by this disease?

The risk to put at the world a phenylcetonuric child for carrying parents is 1 out of 4 .
The frequency in   Belgium of this disease is 1 for 15' 000 births , with the result that it nait each year in Belgium, on average, approximately 3 or 4 phenylcetonuric children.

How is it known if one is reached by it?

To the 4 ^2nd day of life each new-born baby   undergoes a blood test, which makes it possible to seek a certain number of hereditary diseases, before they appear by clinical signs, and which could be prevented by a processing appropri�.Ce test of tracking bears the name of its inventor, Dr. Guthrie, an American pediatrist.
Since 1965, this test of Guthrie made it possible   to measure the phenylalanine rates to the birth at more than 2 million and half of new-born babies.

• 139 true cases of ph�nylc�tonuries at a rate of 1 case for 15.000 births.
• 173 cases of hyperph�nylalanin�mies at a rate of 1 case for 19.000 births.

were detected allowing an early processing by a diet.

The tracking of a deficiency in BH4 must be practised at the new-born babies with phenylalanine rates raised with the birth since the assumption of responsibility of these patients is different from that of the traditional ph�nylc�tonurie.


Don't Ph�nyc�tonurie, hyperphenylalaninemy, moreover, everyone have the same disease?

Not! The concept of tolerance to phenylalanine for a given patient is significant :

• The patients needing a mode bringing from 250 to 350 phenylalanine mg/jour are regarded as having a traditional ph�nylc�tonurie .
• Those needing a contribution from 350 to 400 mg/jour have a moderated ph�nylc�tonurie .
• Those being able to support a contribution from 400 to 600 mg/jour have a light ph�nylc�tonurie .
• Certain patients under free mode maintain blood phenylalanine rates lower than 600 �mol/l , these patients have a hyperphenylalaninemy

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