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Article History

Received: 11 July 2025

Accepted: 14 January 2026

First Online: 31 January 2026

Declarations

:

: The I.Family study was performed following the Declaration of Helsinki. Ethical approval was obtained from the institutional review boards of all nine study centres in their respective countries: Ethics Committee of the Gent University Hospital (15/10/2007, ref: No. EC UZG 2007/243 and 19/02/2013, No. B670201316342), Belgium; Cyprus National Bioethics Committee (12/07/2007, ref: No. EEBK/EM/2007/16 and 21/Feb/2013, No. EEBK/ETI/2012/33), Nicosia, Cyprus; Tallinn Medical Research Ethics Committee (14/06/2007, ref: No. 1093 and 17/January 2013, No. 128), Tallinn, Estonia; Ethics Committee of the University of Bremen (16/01/2007 and 11/12/2012), Bremen, Germany; Medical Research Council (21/06/2007, ref: 22–156/2007-1018EKU and 18/12/2012, 4536/2013/EKU), Hungary; Ethics Committee of the Local Health Authority (19/06/2007, ref: No. 2/CE and 18/Sep/2012, No. 12/12), Avellino, Italy; Bioethical Committee of the University of Rzeszów (05/06/2013 and 01/12/2015), Rzeszów, Poland; Ethics Committee for Clinical Research of Aragon (20/06/2007, ref: No. PI07/13 and 13/Feb/2013, No. PI13/0012), Zaragoza, Spain; Regional Ethics Research Board (30/07/2007, ref: No. 264-07 and 10/Jan/2013, No. 927 − 12), Gothenburg, Sweden. All parents and adolescents above 12 years of age gave written informed consent.

: Not applicable.

: The authors declare no competing interests.