In the pivotal work by Koskela et al. in 2012, which discovered STAT3 mutations in LGLL, STAT3-mutated patients, compared to STAT3-wild-type ones, were more likely to have neutropenia (77% vs. 50%) and RA (26% vs. 6%) [54,62]; these findings were shortly validated by Jerez et al. [60]. The gene discussed is STAT3; the disease is Decreased total neutrophil count.