STAT3 gene mutations and their association with pure red cell aplasia in large granular lymphocyte leukemia

Large granular lymphocyte leukemia (LGLL) has been morphologically characterized as a group of lymphoproliferative diseases that include T-cell large granular lymphocytic leukemia (T-LGLL) and chronic lymphoproliferative disorders of natural killer cells (CLPD-NK). We investigated mutations in the Src homology 2 (SH2) domain of the signal transducer and activator of transcription 3 (STAT3) gene in Asian cohorts of T-LGLL and CLPD-NK (n=42 and 11, respectively). Two mutations, Y640F and D661Y, were identified using direct sequencing or allele-specific (AS) PCR. Y640F and D661Y mutations were found in seven and 18 patients, respectively. Two patients were positive for both mutations. Frequencies of STAT3 mutations in T-LGLL and CLPD-NK were 47.6% and 27.2%, respectively. Pure red cell aplasia (PRCA) was associated with the mutations (P=0.005). The mutations were persistently found at stable levels in some patients after more than 5years using AS-quantitative PCR. The results of the present study indicate that the SH2 domain of the STAT3 gene is frequently mutated in Asian T-LGLL and CLPD-NK, and that PRCA is closely correlated with the mutations. SH2 domain of the STAT3 gene is frequently mutated in Asian T cell large granular lymphocyte leukemia and chronic lymphoproliferative disorders of NK cells. Pure red cell aplasia is closely associated with the mutations.