The yin and the yang of keratin amino acid substitutions and epidermolysis bullosa simplex.

Mutations that change the same amino acid can result in different clinical phenotypes. Through in silico modeling and keratin filament assessment of genetically engineered HaCaT cells, Natsuga et al., as reported in this issue, have demonstrated how changes in charge and structure of a replacement amino acid in keratin 14 can cause disease (KRT14pA413P, EB simplex) or no clinical effect (KRT14pA413T, polymorphism).