A kidney biopsy demonstrated active disease with 60% cellular crescents and glomerular necrosis lesions (Fig. 1) with minimal chronicity of 3% global glomerulosclerosis and 10% tubular atrophy and interstitial fibrosis (Day − 46); ANCA titers were detected via enzyme-linked immunosorbent assay (> 1:1280) to myeloperoxidase and a diagnosis of MPA with rapidly progressive glomerulonephritis was made. The gene discussed is MPO; the disease is glomerulonephritis.