This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blistering disorders, Subject name: Dental
[{'content': 'In congenital junctional epidermolysis bullosa , defect is seen in? \nSelect and explain. \nA. Laminin 5, B. Collagen type 7, C. Collagen 4, D. Collagen 3', 'role': 'user'}, {'content': 'Answer: A \nExplanation: EB comprises a group of genetically determined skin fragility disorders characterized by blistering of the skin and mucosae following mild mechanical trauma. Congenital epidermolysis bullosa of 3 types: 3 types Defect 1. Epidermolysis Bullosa Simplex 2. Epidermolysis Bullosa Junctional 3. Epidermolysis Bullosa Dystrophicans K5 / 14Q LamininQ Collagen-7Q Cogentinal is DIF Negative because no antibodies. Acquired epidermolysis bullosa: Ab against NCD (non collagenous domain) of Collagen 7 therefore DIF Positive', 'role': 'assistant'}]