Conditional logistic regression demonstrated that each incremental U/ml rise of MPO-ANCA increased the odds of future PLN diagnosis compared to both healthy controls and SLE without LN disease controls (OR 9.1 [3.4–24.5], p < 0.001; OR 1.5 [1.2–1.8], p < 0.001, resp.; Table 3). This evidence concerns the gene MPO and systemic lupus erythematosus.