Background: Core binding factor acute myeloid leukemia (CBF-AML) is a form of AML associated with the chromosomal abnormalities t(8;21)(q22;q22) (t(8;21)AML) and inv(16)(p13.1q22)/t(16;16)(p13.1;q22) ...(inv16 AML). It accounts for approximately 8% of AML cases and is considered to be a karyotype with a favorable prognosis. Mutations of c-kit gene which constitute type III tyrosine kinase receptor were found in approximately 30% of patients with CBF-AML. In CBF-AML, KIT mutation is observed mainly in two domains: the extracellular domain (exon8), and the tyrosine kinase domain (exon17), and has frequently been reported to be an unfavorable prognostic factor for early relapse and for shorter survival. On the other hand, some reports conclude that KIT mutation has no prognostic impact in CBF-AML, and in 2016's guidelines of NCCN, CBF-AML with KIT gene mutation was not assigned to the intermediate prognosis group. One potential reason why the reported prognostic impact of KIT mutation in CBF-AML differs between studies is that CBF-AML cases with t(8;21) and those with inv(16) have differing clinical profiles. Another reason is that KIT mutation occurs at various locations on the gene. We have previously reported that KIT D816 in CBF-AML is associated with a higher relapse rate than KIT N822K and has unfavorable prognosis. The aim of the present study was to clarify that these two types of KIT mutations have differing prognostic impacts in CBF-AML.
Methods: We analyzed 138 cases of CBF-AML who achieved complete remission (CR), retrospectively. Mutation analyses were performed by direct sequence analysis Mutation Biased PCR, direct sequence analysis, and the next-generation sequencer Ion PGMTM.
Results: Average age was 45 years (15-80 years). The inv16 AMLand t(8;21) AMLwere28 cases and 110 cases, respectively. KIT mutations were found in 62 (45%) cases of patients with CBF-AML. Patients with KIT mutations were significantly more frequently associated with male gender (p=0.029) and higher white blood cell count (>1×104/μl) (p=0.002) compared to KIT wild type cases. No significant differences were found in other clinical characteristics between those with and without KIT mutations. Analyzing all CBF-AML patients and inv16 AML, rates of relapse free survival (RFS) and overall survival (OS) in those with KIT mutations were significantly lower than those in patients without c-kit mutations (All patients: RFS, 38% vs 58% at 3 years after CR1, p=0.040; OS, 61% vs 77%, p=0.033; inv16 AML: RFS, 46% vs 82%, p=0.044; OS, 75% vs 100%, p=0.045). However, there was no significant difference between t(8;21)AML with and without KIT mutations (RFS, 35% vs 51%, p=0.219, OS, 58% vs 70%, p=0.161). Next, we analyzed prognosis of CBF-AML according to the types of c-kit mutations. D816, N822K, co-expression of D816 and N822K, and other mutations of KIT gene were detected in 29 cases (21%, D816A:1 case, D816Y:2 cases, D816V:26 cases), 20 (14%), 7 (5%, D816H:1 case, D816V:6 cases), and 6 cases (4%), respectively. (RFS, 58.2% vs 21.6% vs 58.9% vs 14.3% vs 60.0%, p=0.005; OS,77.2% vs 40.0% vs 78.9% vs 60.0% vs 100.0%, p<0.001) Rates of RFS and OS in patients with D816 or both of D816 and N822K (D816-positive) were significantly lower than those in patients with KIT wild type or other KIT mutations (D816-negative) (RFS, 20% vs 59%, p<0.001; OS, 43% vs 79%, p<0.001). In stratified analysis of inv16 AML and t(8;21)AML, rates of RFS and OS in the D816-positive patients were significantly lower than those in D816-negative patients (inv16 AML: RFS, 25% vs 85%, p=0.001; OS, 60% vs 100%, p=0.005; t(8;21)AML: RFS, 18% vs 52%, p=0.019; OS, 38% vs 73%, p<0.001). Multivariate analyses for RFS and OS showed that D816 was an independent unfavorable prognostic factor (RFS, HR 2.06, p=0.014; OS, HR 3.12, p=0.003). Consolidation using high-dose AraC was shown to be independently associated with improved RFS.
Conclusions: In ASH meeting of 2014, we showed that the D816V confers higher proliferation activity by JAK-STAT and Src family kinase compared to N822K by in vitro assay. In this study, we showed that patients with D816 had a significantly poorer prognosis than those with N822K or other mutations of KIT in CBF-AML. Going forward, a study is needed in which a trial of autologous stem cell transplantation in first CR or conventional chemotherapy with dasatinib or novel molecular target drug such as PKC 412 for CBF-AML with D816.
No relevant conflicts of interest to declare.
Wolf-Hirschhorn syndrome (WHS), a contiguous gene syndrome caused by heterozygous deletions of the distal short arm of chromosome 4 that includes NSD2, reportedly causes specific DNA methylation ...signatures in peripheral blood cells. However, the genomic loci responsible for these signatures have not been elucidated. The present study aims to define the loci underlying WHS-related DNA methylation signatures and explore the role of NSD2 in these signatures.
We conducted genome-wide methylation analysis of individuals with WHS or NSD2 variants using an array method. We studied genome-edited knockin mice and induced pluripotent stem cells to explore the function of NSD2 variants.
Three undiagnosed cases with NSD2 variants showed WHS-related DNA methylation signatures. In patient-derived induced pluripotent stem cells and genome-edited knockin mice, these variants cause NSD2 loss of function, respectively. The p.Pro905Leu variant caused decreased Nsd2 protein levels and altered histone H3-lysine 36 dimethylation levels similarly to what was observed in Nsd2 knockout mice. Nsd2 knockout and p.Pro905Leu knockin mice exhibited common DNA methylation changes.
These results revealed that WHS-related DNA methylation signatures are dependent on NSD2 dysfunction and could be useful in identifying NSD2 variants of uncertain significance.
Introduction Familial hypercholesterolemia (FH, OMIM number #143890) is an autosomal dominant disorder, resulting in low-density lipoprotein (LDL) receptor dysfunction. The prevalence of FH is ...estimated to be approximately, 1 in 200 and 1 in 170,000 among heterozygotes and homozygotes, respectively. Since FH patients develop severe coronary-artery disease (CAD) due to hypercholesterolemia in early adult life, lipid-lowering treatments must be started at childhood. Although pediatric FH is clinically diagnosed based on the serum LDL cholesterol (LDL-C) levels and a family history of hypercholesterolemia, genetic analysis is useful for a definitive diagnosis, as it can predict the risk stratification of CAD and assist in early diagnosis and intervention, leading to improved prognosis. Here, we present a novel mutation in the LDLR gene, in a patient with heterozygous FH (HeFH).
Although laparoscopy may provide more detailed morphological and histological information about peritoneal damage, its significance in patients with long vintage of peritoneal dialysis (PD) is not ...elucidated.
Findings in 12 patients with PD vintage of 7.3 (5.0-8.4) years who had undergone laparoscopy between 2007 and 2011 were reviewed. Macroscopic (peritoneal change, hypervascular change, adhesion, encapsulation) and histopathological peritoneal findings (interstitial fibrosis, microvascular change, fibrin deposition, inflammatory cell infiltration) were scored and summed as Macro-total score (Macro-TS) and Micro-total score (Micro-TS), respectively. Factors associated with these scores and the relationship between these scores were investigated.
Neither Macro-TS nor Micro-TS were related to PD vintage (p = 0.069 and p = 0.769, respectively); moreover, Macro-TS varied from patient to patient regardless of similar PD vintage. However, Macro-TS showed a significant association with duration of acidic dialysate (p = 0.003).
Macroscopic and microscopic findings via laparoscopy may help the assessment of peritoneal damage in patients with long PD vintage.
Protein O-linked mannose beta 1,2-N-acetylglucosaminyltransferase 1 (POMGnT1) catalyzes the transfer of GlcNAc to O-mannose of glycoproteins. Mutations in the POMGnT1 gene cause muscle-eye-brain ...disease (MEB). POMGnT1 is a typical type II membrane protein, which is localized in the Golgi apparatus. However, details of the catalytic and reaction mechanism of POMGnT1 are not understood. To develop a better understanding of POMGnT1, we examined the substrate specificity of POMGnT1 using a series of synthetic O-mannosyl peptides based on the human alpha -dystroglycan ( alpha -DG) sequence as substrates. O-Mannosyl peptides consisting of three to 20 amino acids are recognized as substrates. Enzyme kinetics improved with increasing peptide length up to a length of 8 amino acids but the kinetics of peptides longer than 8 amino acids were similar to those of octapeptides. Our results also show that the amino acid sequence affects POMGnT1 activity. These data suggest that both length and amino acid sequence of mannosyl peptides are determinants of POMGnT1 substrate specificity.
The dystrophin glycoprotein complex, which connects the cell membrane to the basement membrane, is essential for a variety of biological events, including maintenance of muscle integrity. An ...O-mannose-type GalNAc-β1,3-GlcNAc-β1,4-(phosphate-6)-Man structure of a-dystroglycan (a-DG), a subunit of the complex that is anchored to the cell membrane, interacts directly with laminin in the basement membrane. Reduced glycosylation of a-DG is linked to some types of inherited muscular dystrophy; consistent with this relationship, many disease-related mutations have been detected in genes involved in O-mannosyl glycan synthesis. Defects in protein O-linked mannose β1,2-N-acetylglucosaminyltransferase 1 (POMGnT1), a glycosyltransferase that participates in the formation of GlcNAc-β1,2-Man glycan, are causally related to muscle-eye-brain disease (MEB), a congenital muscular dystrophy, although the role of POMGnT1 in postphosphoryl modification of GalNAc-β1,3-GlcNAc-β1,4-(phosphate-6)-Man glycan remains elusive. Our crystal structures of POMGnT1 agreed with our previous results showing that the catalytic domain recognizes substrate O-mannosylated proteins via hydrophobic interactions with little sequence specificity. Unexpectedly, we found that the stem domain recognizes the β-linked GlcNAc of O-mannosyl glycan, an enzymatic product of POMGnT1. This interaction may recruit POMGnT1 to a specific site of a-DG to promote GlcNAc-β1,2-Man clustering and also may recruit other enzymes that interact with POMGnT1, e.g., fukutin, which is required for further modification of the GalNAc-β1,3-GlcNAc-β1,4-(phosphate-6)-Man glycan. On the basis of our findings, we propose a mechanism for the deficiency in postphosphoryl modification of the glycan observed in POMGnT1-KO mice and MEB patients.
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