Iwona Schymalla's guest is Dr Dorota Korycińska-Chaaban from the Metabolic Diseases Outpatient Clinic at the Institute of Mother and Child.
The topic of phenylketonuria does not feature in the media very often. We want to make up for it. We know that a great challenge for carers of children with phenylketonuria is their nutrition, the implementation of an appropriate diet. What does it involve, where and how do difficulties most often arise?
Phenylketonuria is a genetic disorder caused by a mutation in one of the genes responsible for the production of the enzyme that converts phenylalanine to tyrosine. The clinical manifestations of phenylketonuria result from the accumulation of unprocessed phenylalanine in the body fluids and nervous system. An untreated person has a characteristic appearance: fair skin complexion, blond hair and blue irises, but the most important and serious symptom is severe intellectual disability. Attempts and clinical trials of genetic therapy are being made, but at present there is no causal treatment. On the other hand, the only effective method of preventing the onset of clinical symptoms is the use of a special low-Goalanine diet. This sounds innocuous, but in fact it is not a simple diet. It is a low-phenylalanine diet - not a low-protein diet, as we sometimes hear - that excludes products containing natural protein. The patient cannot consume meat, cold cuts, dairy products, including breast milk. This is only allowed in the neonatal period in limited quantities. He cannot eat ordinary bread, cereal grains, legumes, gelatine, sesame, poppy seeds. There are many restrictions. The source of protein, without which our body cannot function, is special preparations of synthetic mixtures of amino acids. The patient must take these in specific amounts, several times a day. The sources of minerals are vegetables and fruit and special low-protein foods, which are a source of calories. The difficulty of running the diet is that the patient must receive a certain amount of phenylalanine, because it is an amino acid that is essential for the functioning of the human body. And this amount is strictly defined. Therefore, it is necessary to weigh all the products that the patient receives and count the phenylalanine, protein and calorie content in them. In the case of children, this is done by their parents, carers, while adults learn to do it themselves. The preparations are synthetic and have a specific taste and smell. Sometimes it is the case that the patient simply does not accept them. It is easier if the child is treated from newborn, which is the case in Poland because phenylketonuria is diagnosed in the course of screening tests, in the first days of life. The treatment when the disease is diagnosed is implemented before the clinical symptoms appear. This is the only effective method. If treatment starts at the onset of clinical symptoms, 100% success is no longer possible.
Also, can't you stop taking the preparations because the symptoms may get worse?
Yes, treatment must be ongoing. We already know that the toxic effects of phenylalanine on the human brain last a lifetime. If there are periods when the adult patient abandons the diet and minor brain changes occur, returning to the diet causes them to disappear. In contrast, this does not happen during the neonatal, infant and early childhood period. If the lesions are severe, they may diminish a little, but they do not go away.
You point out to the Doctor the difficulties faced by parents of sick children. There are a lot of daily hassles. You have to learn to count, there are some restrictions, for example with travelling. However, by following the diet, one can function normally. And what if a patient with phenylketonuria wants to become a mother, decides to become a mother, what problems does she have to face?
The period of pregnancy in a patient with phenylketonuria is the most important for us after the neonatal period. The pregnant patient is admitted out of turn, immediately, the next working day after the phone call. The ideal situation is if the woman prepares for pregnancy earlier, because the phenylalanine concentrations that ensure the normal development of the child's nervous system up to the age of 12 years should be in the range of 2 to 6 milligrams per decilitre (up to 10 milligrams/decylitre in an adult). A woman who is planning a pregnancy can therefore have up to 10 milligrams per decilitre, while during pregnancy safe concentrations are between 2 and 6mg/ decilitre. Therefore, it would be good for women planning a pregnancy to be in contact with us. We provide our patients with information about maternal phenylketonuria syndrome and they know what the risk is. We select a suitable preparation for this time, as not all can be taken during pregnancy. The patient re-learns to measure and count everything she eats. Adult patients who have already become accustomed to this diet do not count everything exactly every day, but in the case of pregnant women this is necessary.
The preparations are chemical and do not always smell nice or taste good. And pregnant women often suffer from nausea. Pregnancy is, after all, a state in which this sensitivity is particularly exacerbated. Are there preparations indicated for pregnant women?
Of course, there are preparations dedicated to pregnant women. In Poland, these are synthetic mixtures of amino acids and all have a specific taste. It happens that a pregnant patient can take the same preparation that she has been taking so far. And this is good, because there is no problem with accepting it, whereas when it is changed it can be different. This is why we want patients to prepare for pregnancy and get used to a different preparation beforehand. On the other hand, when the patient is already pregnant, she has to accept the preparation immediately, give up everything that is not allowed. There are preparations in the world that are more friendly to taste and smell. These are glycomacropeptides derived from whey proteins, which smell pleasant. In Poland, unfortunately, not all patients have access to these preparations.
You mentioned maternal phenylketonuria, Doctor. This is something we want to avoid. Hence your care and commitment to the pregnant woman. What is maternal phenylketonuria?
This is a syndrome of congenital malformations occurring in the child of a woman who has blood phenylalanine concentrations above the recommended values, i.e. above 6 milligrams per decilitre, during pregnancy. These are very different defects and affect all the systems of the newborn. The newborn itself is not affected by phenylketonuria. Although there are isolated cases. The defects, as I said, can affect any system of the newborn e.g. digestive, facial appearance, fingers. But the main thing is that such children are born with intellectual disabilities, they do not develop properly because their brain cannot develop properly. The good news is that we know how to prevent this syndrome. Preparing for pregnancy and keeping phenylalanine concentrations at safe levels for nine months results in the child developing properly. Although, as in any population, babies can also be born with various other defects.
A difficult moment for adults caring for a child with phenylketonuria is when the child goes to school. At school, the child also has to take these preparations. He or she cannot attend birthdays or name days of classmates because he or she does not eat certain products. Should the school be informed of the child's situation or not? As a practitioner, what advice would you give to parents of children?
A difficult moment is always when a child leaves home. Whether it is nursery, kindergarten or school. Of course, school is more difficult because the child is more independent and wants to meet peers. I would like to emphasise that a child with phenylketonuria who is diagnosed with the disease in a neonatal screening and is treated with a low-phenylalanine diet restrictively and as prescribed develops normally, just like his peers. He can participate in all activities, including birthdays or name days, outings, sports, Olympics. The only condition is to provide him with a diet. But more and more products that are low in protein are even in ordinary shops. We can always ask the organiser of the celebration to stock them. On the other hand, in order for a child to be safe at school, he must first receive proper education from his parents and from us doctors. He or she needs to know which products are allowed for him or her and which are not, to develop the habit - ask before you eat. I wouldn't want our patients to be labelled as having phenylketonuria, they need to know themselves what they can eat. It is customary in schools that if children have a birthday or name day, for example, they bring a treat. Ideally, parents should know that there is a child in the class who cannot eat chocolate sweets, but can eat landflakes. When it comes to the question of whether to talk about the disease at school I always have a dilemma. It is rare, unknown and raises a million questions. It all depends on the environment and the cooperation of the parents. On the other hand, it is essential to say that the child is on a special diet, what he can't and what he can eat. And to the teachers, I would like to say that in phenylketonuria, fortunately, if a child eats a forbidden product, nothing will happen to them straight away. There is no risk here as there is in allergies. Because the preparations have a specific smell, intense and different from what we are used to, it happens that the child does not want to drink them at school. But there is a remedy for this - there are ready-to-drink preparations that look like juices, simply unscrew the cap, drink and throw the packet in the bin. There are also preparations in powder form that dissolve. You can dissolve it in juice and drink it. It seems to me that in the younger grades, the class teacher should be involved to supervise the child. In the older grades the children are already independent. Children with phenylketonuria bring their meals to school with them. They should be able to eat together with the other children, without separating places for them. School in a child's life is inevitable and peer integration and acceptance is very important.
What changes are patients with phenylketonuria waiting for?
Most often, adult patients, somewhat jokingly, ask if there is already a tablet for phenylketonuria that they can swallow and stop the diet. Unfortunately, there are no such tablets yet. I think they are waiting for the same access to modern treatments as there is in the world. In addition to the phenylalanine-deficient diet, there is BH4, which helps to process phenylalanine, and there is enzyme therapy. There are products called glycomacropeptides, which are not available to all patients in Poland. This is a studied preparation and I think it would be accepted by a large proportion of patients. Certainly not all patients would be able to consume it because of a certain phenylalanine content, this should be discussed with a doctor or dietician. I think they are waiting for the adult clinics. In Poland, patients with phenylketonuria are dealt with by paediatricians, individual internists are learning it. Patients are also waiting for reimbursement of low-protein foods, which are expensive, which may be a limitation.
Source: medexpress.co.uk