Logistic regression model predicting probability of biallelic HLH mutations when combining perforin and CD107a expression tests, with or without NK cytotoxicity. ROC display of logistic regression model, showing diagnostic performance of testing with perforin MCF and CD107a MCF together in the model (A) and perforin MCF, CD107a MCF, and NK lytic units together in the model (B) to distinguish patients with biallelic HLH-associated mutations compared with patients with all other genetic results. est., coefficient of the logistic regression model; lr.eta, optimal cut point for the fitted values obtained from the logistic regression model; s.e., standard error for the coefficient; Sens, sensitivity; Spec, specificity.