KRT5 and epidermolysis bullosa simplex: The subtype of EBS associated with mottled pigmentation (EBS-MP) is most often due to a specific mutation, p.Pro25Leu, in the head domain of keratin 5.9–11 The KRT5 mutations reported in GGD and DDD are also within the head domain but are nonsense or frameshift mutations resulting in premature termination codons; these lead to haploinsufficiency of keratin 5 rather than a dominant-negative defect.1