 Epidermolysis bullosa simplex EBS is the most common subtype of epidermolysis bullosa and mutations in keratin genes KRT 514 are responsible for this condition. Painful blisters and keratoderma of the feet are common and the blisters in EBS typically get worse in the summer due to sweating and increased environmental heat. Since 2010, also the related condition pachyonychia congenita PC is included in the study. The primary objective of the study is to evaluate the clinical effect of Botulinum toxin A Dysport, injected in the foot, on plantar pain in patients with EBS or PC. Quality of life, pain in feet, effect duration, plantar sweating and safety of the treatment will also be studied. 