ATP2C1 encodes a P-type ATPase that transports calcium and manganese ions into the Golgi apparatus, maintaining their proper intracellular concentrations essential for protein processing and secretory pathway function. The pump operates through ATP-dependent conformational changes coupled to transient phosphorylation, shifting between inward-facing and outward-facing states to deliver ions across the membrane. In keratinocytes, ATP2C1 is particularly critical for maintaining calcium homeostasis in the trans-Golgi compartment, supporting both proper protein sorting and structural organization of Golgi cisternae while enabling keratinocyte differentiation and epidermis integrity. Hailey-Hailey disease (familial benign chr3 pemphigus) represents the primary clinical manifestation of ATP2C1 dysfunction, occurring at an estimated prevalence of 1/50,000 with autosomal dominant inheritance 1. Heterozygous mutations in ATP2C1 cause decreased protein expression or function, leading to abnormal cytosolic calcium and manganese levels that disrupt adhesion between epidermal keratinocytes through altered synthesis of junctional proteins, resulting in acantholysis and characteristic suprabasal blistering lesions in flexural areas 2. Over 166 pathogenic mutations have been identified worldwide, with both nonsense and missense variants exhibiting haploinsufficiency as the predominant pathogenic mechanism 3. Management of Hailey-Hailey disease is symptomatic, as no cure exists. Treatment approaches include topical agents (corticosteroids, calcineurin inhibitors, antibiotics, calcitriol), systemic medications (retinoids, dapsone, apremilast, immunosuppressants), and procedural interventions such as botulinum toxin and laser therapy 4, though controlled clinical trials supporting optimal treatment selection remain limited.