Up-regulation of K15 expression in the epidermis of 4 EBS patients with ablated K14 has been reported and in these patients K5 was able to polymerise with K15 but the K5/K15 pair could form only 6 nm wispy proto-filaments instead of mature 10 nm keratin filaments [44]. This evidence concerns the gene KRT5 and epidermolysis bullosa simplex.