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'Nobody knows what it is': The rare genetic condition that means people must avoid protein

Despite being rare, Ireland has one of the highest rates of PKU in Europe.

gary Gary

INCREASING THE AMOUNT of protein people eat is often recommended as part of a healthy diet.

However, some people have to strictly monitor the amount of protein they digest or face serious side effects. Phenylketonuria, or PKU, is a rare genetic disorder that affects a person’s metabolism. People with the condition need to maintain low-protein diets.

Despite being rare, Ireland has one of the highest rates of PKU in Europe. About one in every 4,500 babies here is diagnosed with PKU or a milder form of the condition, compared to about one in every 12,000 babies in the UK.

PKU is caused by a defect in the gene that helps create the enzyme needed to break down the amino acid phenylalanine (PHE), which is found mostly in foods that contain protein. Without the enzyme necessary to process phenylalanine, a dangerous build-up can develop when a person with PKU eats foods that are high in protein such as meat, fish and eggs.

According to the HSE, approximately one in every 35 individuals in Ireland carries one affected gene. If both parents of a child carries the defective gene, they have a one in four chance of having a child with PKU.

The PKU Association of Ireland notes that, if untreated, PKU can result in permanent brain damage. Screening for PKU takes place for all newborn babies in Ireland, through the heel prick test, and across Europe.

There is no cure for PKU, but a build-up of PHE in a person’s blood and brain can be prevented through a highly restricted, low-protein diet. People with PKU need to undertake regular blood tests and take dietary supplements.

PKU-Food-pyramid PKU Association of Ireland PKU Association of Ireland

Gary Conway was diagnosed with PKU at birth. The 30-year-old from Dublin says living with the condition can be very difficult.

“I can’t eat foods like meat or fish or nuts. I can only eat very small amount of lentils – they’re not really worth eating.”

People with PKU can order food through the long-term illness (LTI) scheme, but Gary says the selection is “not great” and often of a “really poor quality”.

“The bread is terrible, that’s one of the main problems, everyone talks about that. Something as simple as being able to eat better quality bread could make a huge difference.”

DSC_0129_1 Gary and his girlfriend Ciara

Gary has tasted PKU-friendly foods available in other countries and says the quality is often better, but they would be very expensive to buy. A loaf of bread, for example, could cost about four times more than a normal loaf.

When asked about the foods available to PKU patients through the LTI scheme, Health Minister Simon Harris previously told the Dáil: “The HSE has statutory responsibility for decisions on pricing and reimbursement of products under the community drug schemes, including the LTI Scheme, in accordance with the provisions of the Health (Pricing and Supply of Medical Goods) Act 2013.”

At the time of publication, the HSE had not responded to a request for comment. On its website, the HSE has a breakdown of foods that people with PKU should or shouldn’t eat, they are categorised as:

  • Green foods – those that are safe to eat because they contain very low levels of protein, although they should not be eaten to excess
  • Amber foods – those that contain protein and must be carefully weighed; they will be eaten in different quantities according to the person’s blood phenylalanine level
  • Red foods – foods that should never be eaten under any circumstances

The PKU Association of Ireland describes living with PKU is “a constant daily challenge”.

The PKU low-protein diet has been a major success. It has prevented generations of people from developing acute mental and physical disabilities as a result of their condition. However, it is a punishing and sometimes very difficult diet to stick to, can severely affect a person’s quality of life and can have long-term health consequences.

The association notes that people who have to adhere to such a restricted diet are believed to be at a higher risk of suffering from attention deficit disorders, poor concentration and low energy levels.

The diet may also be associated with an increased risk of obesity and neurological side effects. The association says “much more research is needed in this area”.

Lack of awareness

Gary is speaking out about his condition to mark International Rare Disease Day, which is taking place today.

He says lack of awareness about the condition, including among some healthcare professionals, worries him.

“Unless you have someone in your family with PKU, or a close friend, you’re never going to know anything about it.

“I don’t know what the future is going to hold if I end up in a care home, no place is going to understand what [PKU] is, I worry that I’m not going to be looked after.

Nobody knows what it is, it’s always a big worry for me and other people with PKU who are getting older – that people won’t be able to look after us because they won’t understand our condition.

Gary says during a previous hospital stay he was unable to eat most of the food available as it would aggravate his condition.

As people with PKU often end up eating a lot of carbohydrates, weight gain can be an issue. Gary says this is another difficult element of the condition and something he tries to combat through exercise.

DSC_0172 Gary

The amount of protein a person with PKU can eat varies with each individual and is determined through regular blood testing.

Gary can eat about 15g of protein a day. Until he was 18 years old, he could only eat 8g daily. If he exceeds this limit he begins to feel unwell. Some of the symptoms he experiences include anxiety, headaches and a lack of concentration. It can also affect his speech.

“I develop a speech impediment, it’s really hard to get words outs. It’s not slurring, it’s a bit of a stutter.

“I also lack concentration, I’m not focused, you could be talking to me and I’d simply not be taking it in at all.”


A drug known as Sapropterin or Kuvan is used to treat people with PKU in other countries. It is not suitable for all patients with the condition. A trial of Kuvan was carried out in Temple Street Children’s Hospital in Dublin in 2005 and 2006, with some positive results.

In 2009, the National Centre for Pharmacoeconomics (NCPE) deemed that the drug was not cost-effective and therefore did not recommended the HSE fund it. The drug is again being assessed with a view to it possibly being made available here, something the PKU Association of Ireland is calling for. The NCPE had not responded to a request for comment at the time of publication.

Gary wants a larger trial to be conducted here so more patients with PKU can access the drug. He says the treatment has proved to be a “life-changer” for some people in other countries.

Unless people are given a chance to try it, they won’t know if it works for them. It doesn’t work for everyone but it works wonders for some people, it changes their lives completely.

The PKU Association is currently conducting a survey about the need for new treatment options for people with PKU. The results will be submitted to the NCPE.

More information about PKU can be read here, while more details on Rare Disease Day can be read here.

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