RAS and CSF3R mutations in severe congenital neutropenia

Germline predisposition in myeloid neoplasms: Unique genetic and clinical features of GATA2 deficiency and SAMD9/SAMD9L syndromes

Increasing awareness about germline predisposition and the widespread application of unbiased whole exome sequencing contributed to the discovery of new clinical entities with high risk for the development of haematopoietic malignancies. The revised 2016 WHO classification introduced a novel category of "myeloid neoplasms with germline predisposition" with GATA2, CEBPA, DDX41, RUNX1, ANKRD26 and ETV6 genes expanding the spectrum of hereditary myeloid neoplasms (MN). Since then, more germline causes of MN were identified, including SAMD9, SAMD9L, and ERCC6L2. This review describes the genetic and clinical spectrum of predisposition to MN. The main focus lies in delineation of phenotypes, genetics and management of GATA2 deficiency and the novel SAMD9/SAMD9L-related disorders. Combined, GATA2 and SAMD9/SAMD9L (SAMD9/9L) syndromes are recognized as most frequent causes of primary paediatric myelodysplastic syndromes, particularly in setting of monosomy 7. To date, ~550 cases with germline GATA2 mutations, and ~130 patients with SAMD9/9L mutations had been reported in literature. GATA2 deficiency is a highly penetrant disorder with a progressive course that often rapidly necessitates bone marrow transplantation. In contrast, SAMD9/9L disorders show incomplete penetrance with various clinical outcomes ranging from spontaneous haematological remission observed in young children to malignant progression.

Next-generation sequencing reveals unique combination of mutations in cis of CSF3R in atypical chronic myeloid leukemia

Background

Atypical chronic myeloid leukemia (aCML) is a hematologic disorder characterized by leukocytosis with increased dysplastic neutrophils and their precursors. In CSF3R gene, the activation mutation including T618I is frequently reported in aCML but is rarely accompanied by truncation mutations. Herein, we report a unique aCML patient with two CSF3R mutations (T618I and Y779*) in the same DNA strand.

Methods

High‐coverage next‐generation sequencing for 40 genes related with myeloid leukemia was performed. Sanger sequencing was performed to confirm CSF3R mutations. To confirm whether two CSF3R mutations are in cis or not, TA cloning was used. Clinical information and bone marrow pathology were reviewed by two hematopathologists.

Results

In the patient diagnosed with aCML in bone marrow study, two CSF3R mutations, (T618I and Y779*) a SETBP1 mutation (G870S) and an U2AF1 mutation (Q157P), were identified by high‐coverage next‐generation sequencing. The two CSF3R mutations were confirmed to be located in the same DNA strand by TA cloning, indicating that the two mutations are harbored in one malignant clone. The SETBP1 mutation is known to be related with poor prognosis in aCML. Likewise, the patient was refractory to hydroxyurea and showed disease progression. Additionally, we discussed the potential therapeutic targets by reviewing the molecular profile of the patient.

Conclusion

We believe that the accurate diagnosis and maximum therapeutic chance could be achieved by profiling the mutations and their characteristics.

G-CSF and its receptor in myeloid malignancy

Granulocyte colony-stimulating factor (G-CSF) has been used in the clinic for more than 2 decades to treat congenital and acquired neutropenias and to reduce febrile neutropenia before or during courses of intensive cytoreductive therapy. In addition, healthy stem cell donors receive short-term treatment with G-CSF for mobilization of hematopoietic stem cells. G-CSF has also been applied in priming strategies designed to enhance the sensitivity of leukemia stem cells to cytotoxic agents, in protocols aimed to induce their differentiation and accompanying growth arrest and cell death, and in severe aplastic anemia and myelodysplastic syndrome (MDS) to alleviate anemia. The potential adverse effects of G-CSF administration, particularly the risk of malignant transformation, have fueled ongoing debates, some of which can only be settled in follow-up studies extending over several decades. This specifically applies to children with severe congenital neutropenia who receive lifelong treatment with G-CSF and in which the high susceptibility to develop MDS and acute myeloid leukemia (AML) has now become a major clinical concern. Here, we will highlight some of the controversies and challenges regarding the clinical application of G-CSF and discuss a possible role of G-CSF in malignant transformation, particularly in patients with neutropenia harboring mutations in the gene encoding the G-CSF receptor.