This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Histopathological findings, Subject name: Dental
Defect seen in Hailey Hailey disease? 
Select and explain. 
A. ATP2A2, B. ATP2C1, C. ATP7A, D. ATP7B
B: ATP2C1
Answer: B: ATP2C1 
Explanation: Hailey-hailey disease / Benign familial pemphigus Occurs due to defect in gene: ATP2C1 gene which codes for: SERCA (Sarco Endoplasmic reticulase Ca2+ ATPase). Therefore, in this disease Ca2+ ATPase is defective. Ca2+ required for attachment of two desmosomes. ATP7A mutation causes Menke's disease. ATP7B mutation - Wilson's disease ATP2A2 mutation - Darier's disease.