COL17A1 and Erythema: These anti-BP180 NC16A IgG are positively correlated with the Autoimmune Bullous Skin Disorder Intensity Score and Bullous Pemphigoid Disease Area Index (BPDAI) in its subcomponents of erosion/blister, urticaria/erythema and pruritus scores, while the level of anti-BP230 IgG is not correlated with these scores, suggesting that anti-BP180 NC16A IgG can be a useful indicator of BP activity (54, 55).