7 research outputs found
Locked nucleic acid probes for enhanced detection of FLT3 D835/I836, JAK2 V617F and NPM1 mutations
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Hemochromatois-Associated Gene Mutations in Patients with Myelodysplastic Syndromes with Refractory Anemia and Ringed Sideroblasts
Abstract
Complex interaction between a multitude of genetic variants may be responsible for differential susceptibility to specific diseases, and be responsible for phenotypic variability and heterogeneity of clinical presentations. Such a variability in clinical features confounded for many years investigations into the pathogenesis of myelodysplastic syndromes (MDS). We made a curious observation of increased ferritin levels in some newly diagnosed patients with MDS RARS (refractory anemia with ringed sideroblasts) in whom transfusional iron-overload was unlikely due to very low transfusion burden. Hence, we hypothesized that RARS patients may harbor hemochromatosis-related mutations, which could contribute to the pathophysiology of this particular subset of MDS. We studied a cohort of 109 MDS patients; 42 with RARS, and 67 with other forms of MDS (18 RA, 12 RAEB, 7 RAEB-T, 1 CMML, and 29 MDS/MPD overlap). All patients were genotyped using restriction fragment length polymorphism (RFLP) method, designed to detect presence of C282Y and H63D mutations of the HFE gene. We found significantly higher frequency of heterozygozity for the C282Y mutation in 21% of RARS patients (vs 9% in control population, n=2016, p= 0.017) while H63D genotype was not increased. The possible pathogenic role of this finding in RARS was supported by the normal distribution of mutant HFE alleles in patients with other forms of MDS (5% vs. 9%, p =0.35). Interestingly, 3/7 patients with RA not fulfilling the RARS criteria, but having increased numbers of ringed sideroblasts (<15%) also showed heterozygozity for either C282Y or H63D allele. To correlate the presence of C282Y allele with clinical features of RARS patients, we have performed a subset analysis. Within this group we have included patients with a rather nebulous and rare form of MDS, provisionally subclassified by WHO as RARS with thrombocytosis (RARSt); 7 of these patients (n=10) were found to have either C282Y or H63D allele resulting in a frequency of 30% and 40% of C282Y or H63D allele, respectively. The combined prevalence of either of these alleles in the control population is 33% (vs. 70% in RARSt, p=.01). Previously, we have demonstrated that RARSt patients are characterized by a high prevalence of the V617F JAK2 mutation (Szpurka et al, Blood 2006) suggestive of the pathophysiologic derivation of this syndrome from MPD rather than MDS. Consequently, we have tested the frequency of HFE gene variants associated with hemochromatosis in patients with MPD and Jak2 mutations. Of note is that patients with RARS harbored more C282Y alleles than those with other forms of MDS or MPD with Jak2 mutation (except for those with RARSt; (21% vs 5% and 3%, p =0.036 and .012, respectively). We conclude that hemochromatosis associated mutations may contribute to the pathogenesis of RARS. In patients with MPD and Jak2 mutation, concomitant presence of hemachromatosis-predisposing HFE variants may result in the unusual presentation associated with ringed sideroblasts
Cytoplasmic localization of phosphorylated STAT5 in human acute myeloid leukemia is inversely correlated with Flt3-ITD
Pathologic clonal cytotoxic T-cell responses: nonrandom nature of the T-cell–receptor restriction in large granular lymphocyte leukemia
Biallelic PI4KA variants cause neurological, intestinal and immunological disease.
Phosphatidylinositol 4-kinase IIIα (PI4KIIIα/PI4KA/OMIM:600286) is a lipid kinase generating phosphatidylinositol 4-phosphate (PI4P), a membrane phospholipid with critical roles in the physiology of multiple cell types. PI4KIIIα's role in PI4P generation requires its assembly into a heterotetrameric complex with EFR3, TTC7 and FAM126. Sequence alterations in two of these molecular partners, TTC7 (encoded by TTC7A or TCC7B) and FAM126, have been associated with a heterogeneous group of either neurological (FAM126A) or intestinal and immunological (TTC7A) conditions. Here we show that biallelic PI4KA sequence alterations in humans are associated with neurological disease, in particular hypomyelinating leukodystrophy. In addition, affected individuals may present with inflammatory bowel disease, multiple intestinal atresia and combined immunodeficiency. Our cellular, biochemical and structural modelling studies indicate that PI4KA-associated phenotypical outcomes probably stem from impairment of PI4KIIIα-TTC7-FAM126's organ-specific functions, due to defective catalytic activity or altered intra-complex functional interactions. Together, these data define PI4KA gene alteration as a cause of a variable phenotypical spectrum and provide fundamental new insight into the combinatorial biology of the PI4KIIIα-FAM126-TTC7-EFR3 molecular complex