In this study, considering the limited availability of Vhl cKO mice, we used floxed VHL mice without Col2-CreERT2 as a control, as we and others have done previously.51,58 To exclude the potential interference of Col2-CreERT2 in DDD pathogenesis, the discs of Vhl cKO without TM injection and Cre-negative mice were histologically analyzed using H&E staining at 12 months. This evidence concerns the gene VHL and Dowling-Degos disease 1.