Purpose. Early infantile epileptic encephalopathy (EIEE) 57 belongs to a group of encephalopathies with early-onset and characterised by severe electroencephalogram abnormalities, seizures, developmental delay and intellectual disability. Method. We carried out Whole Exome analysis using Next Generation Sequencing (NGS) and bioinformatic analysis performed to find mutation associated with the patient phenotypes. The effect of the mutation on protein structure analysed by PolyPhen2 and Swissmodel ExPASy. Results. In this study, we evaluated two unrelated Turkish males diagnosed with EIEE type 57 to investigate the genetic cause of this disease. Whole exome sequencing revealed mutations in KCN2 gene, which is a member of Potassium channels (KCN) gene family associated with epileptic encephalopathies. Two mutations, c.545A>T (p.Asn182Ile and c.2638C>A (p.Leu880Met) were reported here as a novel mutation. Conclusions. Our findings implicate the genotype-phenotype correlation of these mutations. Furthermore, the computational analysis showed their effect on protein binding site and function suggesting their role in the development of early infantile epileptic encephalopathy 57.
Additional chromosomal abnormalities (ACAs) in Philadelphia chromosome (Ph)-positive chronic myeloid leukemia (CML) are strongly associated with disease progression, but their prognostic impact and effect on treatment response are not clear. While the onset of ACAs in Ph-negative cells during treatment has been described, their origin and clinical significance remain to be clarified. Between January 2008 and January 2011, 105 patients with Ph-positive CML were analyzed. With a median follow-up of 25.5 months, 18 CML patients (17 %) with ACAs in either CP (n = 12) or advanced phases (n = 6) were identified. The median age of the patients was 53.5 years at diagnosis. ACAs were determined in Ph-positive metaphases of 12 patients and in Ph-negative metaphases of 5 patients. One patient showed trisomy 8 both in Ph-positive and in Ph-negative metaphases. The median follow-up after the detection of ACAs was 11.9 months. None of the patients carrying ACAs in their Ph-negative metaphases developed AP or BP; however, 7 out of 12 patients (58 %) having ACAs in their Ph-positive metaphases developed AP/BC at diagnosis or follow-up (p = 0.03). All the patients carrying ACAs in only Ph-negative metaphases achieved optimal response under tyrosine kinase inhibitor (TKI) therapy, whereas only 4 out of 12 patients (25 %) had optimal TKI response in patients with ACAs in Ph-positive metaphases (p = 0.009). The presence of ACAs in Ph-positive cells during TKI therapy may reflect genetic instability and therefore negatively affect OS. Conventional cytogenic analyses remain mandatory during follow-up of patients with CML under TKI therapy.
Chronic myeloid leukemia (CML) is genetically characterized by the presence of the reciprocal translocation t(9;22) with the formation of Philadelphia (Ph) chromosome. Sometimes, the Ph translocation is generated by variant rearrangements. The prognostic impact of the variant translocations is still controversial. Among the 180 patients with Ph-positive CML who were treated in Hacettepe University Faculty of Medicine Division of Hematology, variant translocations were detected, and retrospectively clinical and prognostic features were described. Also we performed a comprehensive literature review on the prognosis of such variant cases before and after tyrosine kinase inhibitor era. Five patients (2.7%) had variant Ph chromosomes, involved in the rearrangements were chromosomes 2 (2 cases), 11, 14 and 15. Patients were treated with imatinib or dasatinib. All patients reached a stable major molecular response suggesting a prognosis not worse than standard translocation individuals. Our present data were compatible with the data of previous studies indicating no difference in the prognosis between standard and variant translocations in tyrosine kinase inhibitors era of CML.
In chronic myeloid leukemia (CML), epigenetic modifications such as promoter hypermethylation and inactive histone modification are known mechanisms of drug resistance. In our study, we investigated the roles of promoter hypermethylation of BIM and BID genes and H3K27me3 histone modification on imatinib resistance.We detected higher expression levels of BIM and BID genes and lower expression levels of EZH2, EED2, SIRT1, and SUZ12 genes in imatinib-resistant K562/IMA-3 cells compared to imatinib-non-resistant K562 cells. While we determined the EZH2 and DNMT enzymes as bounded to the promoter of the BIM gene, we did not detect hypermethylation of this promoter. We also found the H3K27me3 histone modification promoter of BIM and BID genes in both cell lines. In conclusion, our results support the notion that DNA promoter methylation may be formed independently from EZH2-H3K27me3 and pro-apoptotic BIM and BID genes are not methyllated in the imatinib resistance of CML cells.
Chronic myeloid leukemia (CML) is a hematopoietic malignancy characterized by the t(9; 22) and the related oncogene, BCR-ABL. Tyrosine kinase activity of fusion protein BCR-ABL is the main cause of CML. Even if imatinib is used as a tyrosine kinase inhibitor (TKI) for CML therapy, drug resistance may occur in patients and the clinical failure of imatinib treatment in resistant patients had resulted with the use of another alternative TKIs. BCR-ABL dependent and independent molecular mechanisms have crucial roles in drug resistance. To reveal the underlying molecular mechanisms which play significant roles in imatinib resistance in CML, we established K562 imatinib-resistant cell line (K562r5) which was continuously exposed to (5µM) imatinib to investigate molecular mechanisms which play significant roles in drug resistance. First of all, we analyzed T315I, M351T, F315L and F359C/L/V mutations with DNA sequencing as a BCR-ABL dependent mechanism in our cell lines. Moreover, we investigated BCR-ABL independent mechanisms such as apoptosis, autophagy, drug transport and DNA repair which affect drug resistance in these cell lines. In vitro cell viability was determined by MTT assay. DNA sequencing analysis was performed to detect BCR-ABL mutations. The apoptotic effect of imatinib on CML cell lines was tested by flow cytometric Annexin V-PE staining and caspase activation assays.Apoptotic, autophagic, drug transporter and DNA repair genes expression levels were determined by RT-PCR. The conventional cytogenetic analysis was performed on K562s and K562r cells. Our results indicate that inhibition of apoptosis, induction of autophagy, overexpression of efflux gene MDR1 and down-regulation of influx gene OCT1 play crucial roles in the progression of imatinib resistance.
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