Received: 26 March 2020
Accepted: 14 September 2020
First Online: 5 October 2020
Ethics approval and consent to participate
: Approval for this study was obtained from the Ethics Committee of Tehran University of Medical Sciences (ID: 1397.091). The study adhered to the tenets of the Helsinki Declaration at all stages. Prior to enrollment, the goals and methods of the study were explained to the normal groups and parents of DS patients and written consent was obtained. For all cases in the three DS groups, informed consent were obtained from their parents/guardians, and participants were asked for verbal assent before any procedure.
: Not applicable.
: The authors declare that they have no competing interests.