Funding for this research was provided by:
Norwegian National Advisory Unit on Rare Disorders (Not applicable)
Received: 10 July 2019
Accepted: 16 March 2020
First Online: 30 March 2020
Ethics approval and consent to participate
: This study complies with the Declaration of Helsinki and was approved by the Norwegian Regional Ethics Committee (2017/1516/REK vest). All participants provided written informed consent.
: Not applicable.
: The authors declare that they have no competing interests.