Summary. DNA from 110 adult de novo acute myeloid leukaemia (AML) patients exhibiting either inv(16) (n ¼ 63) or t(8;21) (n ¼ 47) was screened for mutations in the c-KIT (exon 8 and Asp816) and FLT3 (ITD and Asp835) genes. c-KIT exon 8 mutations were found in 15/63 (23AE8%) inv(16) patients and 1/47 (2AE1%) t(8;21) patients. c-KIT Asp816 mutations were present in 5/63 (7AE9%) inv(16) AML and 5/47 (10AE6%) t(8;21) AML. FLT3 mutations were identified in five patients (7AE9%) with inv(16) and three patients (5AE6%) with t(8;21) AML. All mutations were mutually exclusive; 40% of inv(16) AML patients possessed either a c-KIT or FLT3 mutation. c-KIT exon 8 mutations were shown to be a significant factor adversely affecting relapse rate.

Severe congenital neutropenia (SCN) is a BM failure syndrome with a high risk of progression to acute myeloid leukemia (AML). The underlying genetic changes involved in SCN evolution to AML are largely unknown. We obtained serial hematopoietic samples from an SCN patient who developed AML 17 years after the initiation of G-CSF treatment. Nextgeneration sequencing was performed to identify mutations during disease progression. In the AML phase, we found 12 acquired nonsynonymous mutations. Three of these, in CSF3R, LLGL2, and ZC3H18, co-occurred in a subpopulation of progenitor cells already in the early SCN phase. This population expanded over time, whereas clones harboring only CSF3R mutations disappeared from the BM. The other 9 mutations were only apparent in the AML cells and affected known AML-associated genes (RUNX1 and ASXL1) and chromatin remodelers (SUZ12 and EP300). In addition, a novel CSF3R mutation that conferred autonomous proliferation to myeloid progenitors was found. We conclude that progression from SCN to AML is a multistep process, with distinct mutations arising early during the SCN phase and others later in AML development. IntroductionSevere congenital neutropenia (SCN) is a BM failure syndrome characterized by strongly reduced neutrophil counts and recurrent, potentially life-threatening, opportunistic bacterial infections. Treatment with G-CSF elevates peripheral neutrophil counts and reduces the risk of infections. 1 Leukemic progression of SCN is a major concern, with an estimated overall cumulative incidence of approximately 20% after 15 years of G-CSF treatment. 2 Constitutional mutations in the gene encoding neutrophil elastase (ELANE) are common defects in SCN. 3 In addition, the acquisition of nonsense mutations in the gene encoding the G-CSF receptor (CSF3R) is a unique feature in SCN patients. [4][5][6][7] These mutations lead to the expression of truncated CSF3R proteins, also known as the ␦ forms. In cell-line models, truncated CSF3R proteins are hampered in transducing the signals required for proper neutrophil differentiation, confer increased proliferative responses to G-CSF treatment, but do not cause leukemia in mice. [4][5][6][8][9][10][11] CSF3R␦ mutations can be detected in approximately 30% of SCN patients. In some cases, distinct clones with different CSF3R␦ mutations are present for many years. 7,12 After evolution of SCN toward acute myeloid leukemia (AML), CSF3R␦ mutations are found in approximately 80% of patients. 12 Until now, all reported SCN/AML patients harboring a CSF3R␦ mutation in the SCN phase also carry this mutation in the leukemic phase. These observations suggest that leukemic progression in SCN follows a unique pattern, with CSF3R␦ mutations as an early event, followed by additional genetic and epigenetic events that are essential for full leukemic transformation. Chromosomal aberrations such as loss of chromosome 7 and gain of chromosome 21 are apparent in AML arising from SCN and other BM failure syndromes such as Fanconi anemia and Shwachman-Dia...

ABSTRACTnucleotide polymorphism arrays is the fact that allele losses are directly recognizable as loss-of-heterozygosity. In fact, single nucleotide polymorphism arrays revealed that approximately 20% of cases of AML exhibit large nonrandom regions of homozygosity without changes in copy number as a result of segmental uniparental disomy, often indicating mutations in genes within these regions. These areas of uniparental disomy have been associated with mutations in CEBPA, WT1, FLT3 and RUNX1. 15,16

Bone cells produce multiple growth factors that have effects on bone metabolism and can be incorporated into the bone matrix. Interplay between these bone-derived growth factors and calciotropic hormones has been demonstrated in cultured bone cells. The present study was designed to extend these observations by examining the interactions between either transforming growth factor-␤ (TGF-␤) or insulin-like growth factor-I (IGF-I)

No abstract