Indeed, in the present study, the PPV for bi-allelic degranulation gene mutations in patients with CD107a < 5% was 38.9% (7/18), the PPV for bi-allelic degranulation gene mutations in patients with CD107a ≤10% was 16.7% (13/78), and the PPV for primary HLH was 41.4% (29/70) in patients with NK cell activity ≤13%. The gene discussed is LAMP1; the disease is hemophagocytic syndrome.