Oral disorders in Children with Prader-Willi syndrome: a case control study.

Dear Editor, This letter is about the article published by Carla Munné-Miralvés et al. [[1]] about the oral disorders in children with Prader-Willi syndrome. A case-control study is a retrospective study to establish the association between a disease and related factors, and there is no such study design called "cross-sectional observational case-control study". Since this study did not investigate any factors causing PWS, case-control study design is not an appropriate study design in this situation. [Extracted from the article]