C4A and myositis disease: Other “routine initial” testing: ANA (usually speckled), myositis-specific antibodies and myositis-associated antibodies, CBC, differential, CRP (elevated in overlap syndrome but not usually in JDM), ESR (usually normal range), U/A, BUN, Cr, neopterin—for macrophage activation; flow cytometry (for levels of both B cells and natural killer cells), C4 (for C4 null alleles), von Willebrand factor antigen (and blood group for normal ranges), vitamin D, DXA, and nailfold (periungual) capillary end row loop data [21].