Masson’s trichrome staining repeatedly revealed evident structural abnormalities uniquely detected in ALS-TES including an undifferentiated epidermis, cohesive failure of the stratum corneum, abnormal dermo-epidermal junction, delamination, keratinocyte infiltration, as well as collagen misorganization in both C9orf72 FALS- and SALS-derived skins (Figure 1 and Additional file 4: Table S2). The gene discussed is C9orf72; the disease is amyotrophic lateral sclerosis.