PRTN3 and IgA glomerulonephritis: As one of the patients with a positive IgG anti-CCP2 and the patient with borderline IgG anti-CCP2 levels at baseline were both diagnosed with IgA nephropathy and as IgA nephropathy has been reported to occur more frequently in patients with inflammatory diseases such as spondyloarthritis, we were interested whether the presence of low titer ACPA is a common feature of patients with IgA nephropathy[35, 36].