Recessive dystrophic epidermolysis Bullosa occurs due to alteration in:
"Nikolsky's sign" is positive in: 

Pemphigus
Familial benign chronic pemphigus (hailey-hailey disease)
Recessive dystrophic epidermolvsis bullosa [Epidermolysis bullosa occurs due to alteration in structure of type VII  collagen.
Type 4 collagen
Type 6 collagen
Type 7 collagen
Type 8 collagen