Clinical significance of SF3B1 mutations in Korean patients with myelodysplastic syndromes and myelodysplasia/myeloproliferative neoplasms with ring sideroblasts

Somatic mutations in the SF3B1 gene, a gene encoding the splicing factor 3B subunit 1, were recently reported in myelodysplastic syndromes (MDS), particularly in the presence of ring sideroblasts (RS). The authors investigated the prevalence and clinical significance of SF3B1 mutations in Korean patients with myeloid neoplasms with RS. The study subjects were 43 Korean patients with myeloid neoplasms. Twenty-nine patients (67 %) had 15 % or more RS (high-count RS [HC-RS]), and 14 (33 %) had RS less than 15 % (low-count RS [LC-RS]). Molecular genetic tests were performed to detect SF3B1 mutations by direct sequencing on bone marrow samples of the patients. SF3B1 mutations were detected in 55 % (16/29) of the HC-RS group: 3 RARS (3/3), 8 RCMD (8/16), 3 RARS-t (3/4), 1 RAEB (1/4), and 1 MDS-U (1/1). All mutations were previously reported mutations with K700E being the most common (63 % of mutation-positive cases). On the other hand, none (0 %) of the LC-RS group had SF3B1 mutation. The patients with SF3B1 mutations had higher platelet counts (p = 0.023), higher proportions of RS (p = 0.003), and lower proportions of bone marrow blasts (p = 0.026) than those without SF3B1 mutations. SF3B1 mutations showed a favorable survival implication (p = 0.025), but not in multivariate analysis (p = 0.178). This study confirmed that SF3B1 mutation is highly specific to the HC-RS phenotype in Korean patients with myeloid neoplasms with similar frequencies and distributions in previous findings and is associated with distinct hematologic features.