Do not leave people with phenylketonuria alone05.09.2020 – About 1 in 8.000 children in Europe are born with phenylketonuria (PKU) – a rare disease that affects protein metabolism. It can lead "to severe mental developmental disorders," explains Dr. Anja Reichert, medical director at the biotechnology company BioMarin in Germany. Patients need lifelong treatment. However, according to studies, only 12 percent of people with the condition in Europe receive adequate medical care.
No meat, no fish, and no cheese; also legumes, commercial bread, pasta or rice are out of the question for people with PKU. The reason: these foods contain too much protein.
PKU sufferers have to follow a strict low-protein diet due to their disease. Because their body cannot break down the amino acid phenylalanine (Phe) contained in protein well. The reason is mutations in a specific gene, which causes the enzyme with the complicated name phenylalanine hydroxylase (PAH) not to work or to work only to a limited extent. The result: excessive Phe levels in the blood and brain. In addition to severe mental developmental disorders, epilepsy, spasticity or hyperexcitability, among others, can occur without treatment, knows Dr. Anja Reichert, BioMarin.
Dr. Anja Reichert. Photo: BioMarin Germany GmbH
Strict diet in PKU: "very stressful"
"Although PKU is a rare disorder, it is nevertheless one of the most common inherited metabolic disorders," explains the doctor. The diagnosis is usually made immediately after birth via newborn screening, which has been available in Germany since 1969. "The default is to start treatment in the first ten days". The focus is on the strict, low-protein diet: it is "very stressful," says Reichert.
"Only natural foods that contain almost exclusively carbohydrates or fats can be considered." Not much left over: select fruits and vegetables. For things like pasta or bread, sufferers must resort to low-protein special preparations available for purchase online. "The bodies of the patients nevertheless need a lot of protein. That is replaced by completely synthetic mixtures in the form of shakes: they contain all amino acids except Phe."
As part of the "Live Unlimited PKU" campaign, which is financially supported by BioMarin, PKU patient Eva looks back on her childhood: "When I was eating, I felt uncomfortable. Everyone ate something 'normal,' only my food looked weird. Sometimes there would be comments from the other kids like 'What is that?' or' 'That looks like poop shit.'"
In addition, eating is a central part of our social life: "But spontaneous eating out with family, friends or colleagues is simply not possible. That's really limiting," laments Reichert. Let's go to the restaurant? An almost hopeless endeavor.
Patients with PKU in a vicious circle
Protein-containing food: PKU sufferers must abstain from this in a strict diet. Photo: ©iStock.com/a_namenko
"Children still adhere to the diet quite well because parents are very strict about it," she explains. "But starting at puberty, there are fewer and fewer adolescents who completely follow through with the diet. And among adults, only very few still manage it."
An improper diet causes Phe levels in the blood to rise. "Various neurological and psychological problems occur – be it concentration problems, headaches, declining attention or even paralysis, for example". It's a gradual process that takes years, so it often goes unnoticed by sufferers how much their performance declines. But the worse they feel, the more they lack the drive to take up a strict diet – a vicious circle.
Available PKU therapy options
In addition to a selection of dietary foods for PKU patients, there are two drug options – both from BioMarin. The oral medication is used in PKU patients of all ages, provided they respond to this therapy in a previous test. The second option – injection therapy – is used to treat PKU patients 16 years of age and older who have poorly controlled blood phenylalanine levels despite prior treatment with available therapeutic options (d.h.: phenylalanine level in the blood> 600 µmol/l).
In healthy people, blood Phe levels are less than 120 µmol/l. With PKU it is very difficult to get into the normal range. Not only because it's a big challenge to stick to the strict diet for the long haul. "But also because it is always a trade-off," says Reichert. "How much phenylalanine is too much, how much is too little; how do I ensure as balanced a supply of other important nutrients as possible despite dieting?" It resembles a tightrope act.
Adult PKU patients fall through the cracks
Children and adolescents with PKU are "well cared for" in Germany; there are "sufficient pediatric special outpatient clinics" for them, the expert knows. "For a long time it was amed that PKU was a children's disease. It was thought: If sufferers stuck to the diet at a young age, that would be enough. As adults they do not need special treatment." This has since turned out to be a fallacy: "The disease requires lifelong therapy. Adults in whom Phe levels are too high also experience poor concentration and the like." But because the focus in the past was on pediatrics, there is a lack of adult centers today. "If patients don't happen to live near one of the few specialized centers, they get lost in the general medical care system."
For "Live Unlimited PKU", for example, PKU patient Michelle tells how she sought help at the age of 25: "I went to all the family doctors in the area, but was always turned away. I was desperate. Felt miserable. […] No one felt responsible for me." Being left alone – "that was very bitter." PKU patient Eva reports similar: "I feel that as I get older, people pay less and less attention to me." The care situation is becoming increasingly confusing: "Which doctor will take care of me in the future??" or "Who knows about my blood test results?", are just two of the many questions weighing on the young woman's mind. "Between the 18. and 20. I continued to be treated by my pediatrician when I was older – even though I was already an adult. Now I am 20 years and I do not have a doctor anymore."
PKU: body cannot break down well the amino acid phenylalanine contained in protein. Photo: ©iStock.com/Zerbor
Dr. Anja Reichert demands: "Among other things, more doctors should be trained as metabolism experts and corresponding services should be increasingly offered at universities and specialized metabolism centers." Only in this way could the supply gap, which arises from the age of 18 years, be closed. The goal must be to make the transition from a pediatric to an adult center seamless – and to ensure continuity of care. In addition, each center needs uniform treatment and disease management goals, and access to patient-specific therapy and care by a multidisciplinary team of nutritionists, physicians and psychologists for all patients.