MYD88 L265P Mutations Are Correlated with 6q Deletion in Korean Patients with Waldenström Macroglobulinemia

Abstract

Waldenström macroglobulinemia (WM) is a malignant lymphoplasma-proliferative disorder with IgM monoclonal gammopathy. A recent whole-genome study identified MYD88 L265P as the key mutation in WM. We investigatedMYD88mutations in conjunction with cytogenetic study in 22 consecutive Korean WM patients. Conventional G-banding and interphase fluorescencein situhybridization (FISH) were performed at regions including 6q21 using bone marrow (BM) aspirates. Sixteen patients were subjected to Sanger sequencing-basedMYD88mutation study. Five patients (28%) showed cytogenetic aberrations in G-banding. The incidence of 6q21 deletion was 17% by conventional G-banding and 37% by FISH. Ten patients (45%) showed cytogenetic aberrations using FISH: 6q deletion in eight (37%) andIGHrearrangement in four (18%). Two patients had both the 6q deletion andIGHrearrangement, and two had only theIGHrearrangement. Eleven patients (69%) presented with the MYD88 L265P mutation.MYD88mutations were significantly associated with the presence of 6q deletions (P=0.037). Six patients with the 6q deletion for whom sequencing was possible were found to harborMYD88mutations. The MYD88 L265P mutation was also associated with increased lymphocyte burden in BM biopsy. This is the first report of high frequency MYD88 L265P mutations in Korean WM patients.