Moreover, mutations on the genes of γ-secretase components such as PS1, Pen2, or Nicastrin that cause γ-secretase haploinsufficiency are reported to cause familial acne inversa (Wang et al., 2010) and/or Dowing-Degos disease associated with acne inversa (Ralser et al., 2017). This evidence concerns the gene NCSTN and hidradenitis suppurativa.