Wenyi Shen

Deep sequencing reveals stepwise mutation acquisition in paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a nonmalignant clonal disease of hematopoietic stem cells that is associated with hemolysis, marrow failure, and thrombophilia. PNH has been considered a monogenic disease that results from somatic mutations in the gene encoding PIGA, which is required for biosynthesis of glycosylphosphatidylinisotol-anchored (GPI-anchored) proteins. The loss of certain GPI-anchored proteins is hypothesized to provide the mutant clone with an extrinsic growth advantage, but some features of PNH argue that there are intrinsic drivers of clonal expansion. Here, we performed whole-exome sequencing of paired PNH+ and PNH- fractions on samples taken from 12 patients as well as targeted deep sequencing of an additional 36 PNH patients. We identified additional somatic mutations that resulted in a complex hierarchical clonal architecture, similar to that observed in myeloid neoplasms. In addition to mutations in PIGA, mutations were found in genes known to be involved in myeloid neoplasm pathogenesis, including TET2, SUZ12, U2AF1, and JAK2. Clonal analysis indicated that these additional mutations arose either as a subclone within the PIGA-mutant population, or prior to PIGA mutation. Together, our data indicate that in addition to PIGA mutations, accessory genetic events are frequent in PNH, suggesting a stepwise clonal evolution derived from a singular stem cell clone.

BRCC3 mutations in myeloid neoplasms

Next generation sequencing technologies have provided insights into the molecular heterogeneity of various myeloid neoplasms, revealing previously unknown somatic genetic events. In our cohort of 1444 cases analyzed by next generation sequencing, somatic mutations in the gene BRCA1-BRCA2-containing complex 3 (BRCC3) were identified in 28 cases (1.9%). BRCC3 is a member of the JAMM/MPN+ family of zinc metalloproteases capable of cleaving Lys-63 linked polyubiquitin chains, and is implicated in DNA repair. The mutations were located throughout its coding region. The average variant allelic frequency of BRCC3 mutations was 30.1%, and by a serial sample analysis at two different time points a BRCC3 mutation was already identified in the initial stage of a myelodysplastic syndrome. BRCC3 mutations commonly occurred in nonsense (n=12), frameshift (n=4), and splice site (n=5) configurations. Due to the marginal male dominance (odds ratio; 2.00, 0.84–4.73) of BRCC3 mutations, the majority of mutations (n=23; 82%) were hemizygous. Phenotypically, BRCC3 mutations were frequently observed in myelodysplastic syndromes and myelodysplastic/myeloproliferative neoplasms and associated with -Y abnormality (odds ratio; 3.70, 1.25–11.0). Clinically, BRCC3 mutations were also related to higher age (P=0.01), although prognosis was not affected. Knockdown of Brcc3 gene expression in murine bone marrow lineage negative, Sca1 positive, c-kit positive cells resulted in 2-fold more colony formation and modest differentiation defect. Thus, BRCC3 likely plays a role as tumor-associated gene in myelodysplastic syndromes and myelodysplastic/myeloproliferative neoplasms.

Origins of myelodysplastic syndromes after aplastic anemia

To the editor:nnThe course of aplastic anemia (AA) is often complicated by the development of clonal disorders such as paroxysmal nocturnal hemoglobinuria (PNH) and secondary myelodysplastic syndromes (sMDS).[1][1][⇓][2][⇓][3][⇓][4]-[5][5] Identification of patients at risk for development of

Response to cyclosporine A and corticosteroids in adult patients with acquired pure red cell aplasia: serial experience at a single center

To assess response to cyclosporine A, and/or corticosteroids, and possible factors influencing the response in adult patients with acquired pure red cell aplasia (PRCA). Clinical data from 42 cases were retrospectively analyzed. These patients received cyclosporine A (CsA), and/or corticosteroids (CS), or other immunosuppressive agents on becoming refractory and relapse. Thirty-nine patients were evaluated. Remission induction therapy included CsA (nu2009=u200916), CS (nu2009=u200913), CsA in combination with CS (nu2009=u20096), or other immunosuppressive agents (nu2009=u20094). Initial response rates were 75.0, 46.2, 66.7 and 75.0%, respectively (Pu2009=u20090.456). Cumulative response rates in patients who received CsA, CS, CsA in combination with CS, or other immunosuppressive agents were 69.6% (16/23), 50.0% (7/14), 71.4% (5/7), 42.9% (6/14), respectively (Pu2009=u20090.376). Cumulative rates of CR were 26.1% (6/23), 28.6% (4/14), 57.1% (4/7), 14.3% (2/14), respectively (Pu2009=u20090.284). In 27 refractory and relapsed PRCA patients, 11 of 17 patients (64.7%) achieved remission by CsA and/or CS regimen, while three of ten patients (30.0%) responded to other immunosuppressive agents (Pu2009=u20090.120). CsA and/or CS were effective in treating PRCA. For patients with relapse or refractory PRCA, there were no satisfactory treatments if CsA and/or CS failed or were not administered.

The third-time chronic myeloid leukemia in lymphoblastic crisis with ABL1 kinase mutation induced by decitabine, dexamethason combined with nilotinib and dasatinib.

Abstract Blast crisis (BC) is the major remaining challenge in the management of chronic myeloid leukemia (CML). The prognosis of the BC patient who carries ABL kinase mutation is very poor. One patient, with lymphoid CML-BC third time, was detected with T315A/F359I/M244V compound mutation by direct sequencing after treatment with tyrosine kinase inhibitions three years. The patient was treated with decitabine, dexamethasone, in combination with nilotinib and dasatinib. Then this patient received a complete hematologic response and cytogenetic response after two cycles of treatment.