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Short Summary of the SSIEM Annual Symposium, 2018

Short Summary of the SSIEM Annual Symposium, 2018
  • Endocrinology and metabolism
  • Phenylketonuria (PKU)


Resource type



mice studies
treatment adherence and compliance

Short Summary of the Society for the Study of Inborn Errors of Metabolism (SSIEM) Annual Symposium, 

Athens, Greece, 4-7 September 2018

The SSIEM never fails to disappoint with a wide range of posters and papers specifically on PKU with new concepts about dietary management or confirmatory research to support existing work. The latest reports on glycomacropeptide, slow release protein substitutes and PKU gut microbiota were featured but three studies discussing new perspectives of traditional, established dietary management will be discussed in these meeting highlights.

Danique van Vliet (University Medical Centre of Groningen, The Netherlands) has previously described several elegant mice studies examining the impact of large neutral amino acids (LNAA) on brain and plasma amino acids and their ability to restore brain monoamines, including dopamine, norepinephrine and serotonin. At the SSIEM, as a continuation of her work, she reported a study whereby either LNAA (supplements of L-tyrosine, L-valine, L-isoleucine, L-leucine, L-methionine, L-histidine, L-tryptophan and L-threonine) with or without partial phenylalanine (Phe) restrictions were compared with 1) Phe restrictions only of varying severity or 2) a normal diet (in total, 7 different dietary conditions were compared). She studied both PKU mice and wild-type mice for 10 weeks. The results of LNAA treatment without additional Phe restriction was comparable to a severely restricted diet when brain monoamine concentrations were assessed, but also comparable to a moderate Phe-restricted diet when brain Phe concentrations were assessed. Certainly, in these carefully conducted systematic mice studies by the Groningen team, evidence is growing to support LNAA as an attractive alternative management strategy in PKU mice; it is hoped that these study findings translate to adult patients with PKU unable to manage a low Phe diet.  

The Porto team from Portugal presented their examination of Phe tolerance in patients aged ≥12 years with PKU. In preparation for a sapropterin trial, 40 patients were challenged with extra natural protein over a few months prior to sapropterin testing. Patients were aiming to maintain blood Phe ≤480 µmol/L. Sixty-five per cent of patients (n=26) were able to tolerate more natural protein with a median daily protein increase of 12 g (range from 2 to 42 g/day), although around 80% of patients had milder or moderate PKU. This study demonstrated the importance of continual re-assessment of natural protein intake over time. Many patients struggle with dietary management, so it is disappointing if they are not able to enjoy eating natural protein intake according to their full tolerance. 

A further interesting study was by Chiara Cazzorla and colleagues (University of Padova, Italy) who conducted a study including 5 Italian PKU centres studying management adherence in 111 adult patients with PKU. Similar to previous reports in adulthood, overall dietary adherence was poor, and reasons for this was studied. Just under half of the respondents did not consider PKU to be a disease and overall respondents demonstrated a lack of awareness of signs and symptoms that might be associated with PKU. Even so, they were reporting symptoms such as fatigue, irritability and mood swings at least twice per week. It was also discussed that some of the adults did not have enough knowledge or self-skills to take responsibility for their condition and that professionals needed to invest more time on education and structured transitional processes to help support their patients better. Support from the patient’s family was an important factor in successful dietary management. 

Therefore, in a SSIEM meeting that was full of the latest novel science and technology it is also important to pay attention to research that directs day-to-day management of patients and improves the quality of their care pathway. 

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