Received: 28 November 2019
Accepted: 25 February 2020
First Online: 3 April 2020
Ethics approval and consent to participate
: The need for formal ethical review was waived by the local ethics committee of the UMCG. The study design was in accordance with the current revision of the Helsinki Declaration.
: Not applicable.
: E van Dam has received advisory board fees from Biomarin and Merck Serono. FJ van Spronsen has received advisory board fees from SOBI, Merck Serono, Biomarin, Nutricia, APR, Arla Food int., and Promethera, research grants from SOBI, Merck Serono, Biomarin, Nutricia, Alexion, Codexis, NPKUA, ESPKU and the Tyrosinemia Foundation, honoraria as consultant for Merck Serono, Biomarin, Nutricia, and APR, and honoraria as speaker for Merck Serono, Biomarin, Nutricia, Vitaflo and MendeliKABS. All other authors have indicated that they have no conflicts of interest to declare.