It is noteworthy that while patients with MPO-ANCA positivity were more likely to have worse kidney disease at outset compared with PR3-ANCA positive patients, they were also more likely to have more pronounced improvements in kidney function; these improvements were more pronounced for individuals presenting with severely reduced kidney function or kidney failure (KDIGO stages 4–5) compared with PR3-ANCA seropositive individuals with similarly poor baseline kidney function. The gene discussed is MPO; the disease is kidney disorder.