We then evaluated in multivariate analysis the factors predicting seropositivity in patients with hematologic malignancies, and found that, while underlying diagnosis and patients’ age had no impact, male gender, use of anti-B-cell targeting treatment within the previous 12 months, and low CD19+ B-cell numbers (below the normal threshold) were associated with a failure to achieve seropositivity. This evidence concerns the gene CD19 and hematologic disorder.