Diagnostic accuracy of CD107a expression for detecting biallelic degranulation gene mutations. (A) Sensitivity/specificity/PPV/NPV of low CD107a MCF to distinguish any biallelic degranulation gene mutation (UNC13D, STX11, STXBP2, RAB27A, LYST, or AP3B1) from patients with all other genetic-sequencing results. (B) Sensitivity/specificity/PPV/NPV of low CD107a MCF to distinguish any biallelic degranulation gene mutation from patients with normal genetic results. (C) Distribution of CD107a MCF results among patients with no mutations, 1 or more VUCS, carriers (with or without additional VUCS), and patients with biallelic mutations. (D) ROC curve showing diagnostic accuracy of CD107a MCF to distinguish patients with biallelic degranulation gene mutations compared with patients with all other sequencing results; sensitivity and specificity are shown at the optimal diagnostic cutoff of CD107a MCF ≤ 143.