What has GWAS done for HLA and disease associations?

The major histocompatibility complex (MHC) is located in chromosome 6p21 and contains crucial regulators of immune response, including human leucocyte antigen (HLA) genes, alongside other genes with nonimmunological roles. More recently, a repertoire of noncoding RNA genes, including expressed pseudogenes, has also been identified. The MHC is the most gene dense and most polymorphic part of the human genome. The region exhibits haplotype-specific linkage disequilibrium patterns, contains the strongest cis- and trans-eQTLs/meQTLs in the genome and is known as a hot spot for disease associations. Another layer of complexity is provided to the region by the extreme structural variation and copy number variations. While the HLA-B gene has the highest number of alleles, the HLA-DR/DQ subregion is structurally most variable and shows the highest number of disease associations. Reliance on a single reference sequence has complicated the design, execution and analysis of GWAS for the MHC region and not infrequently, the MHC region has even been excluded from the analysis of GWAS data. Here, we contrast features of the MHC region with the rest of the genome and highlight its complexities, including its functional polymorphisms beyond those determined by single nucleotide polymorphisms or single amino acid residues. One of the several issues with customary GWAS analysis is that it does not address this additional layer of polymorphisms unique to the MHC region. We highlight alternative approaches that may assist with the analysis of GWAS data from the MHC region and unravel associations with all functional polymorphisms beyond single SNPs. We suggest that despite already showing the highest number of disease associations, the true extent of the involvement of the MHC region in disease genetics may not have been uncovered.

SYNE1 related cerebellar ataxia presents with variable phenotypes in a consanguineous family from Turkey.

SYNE1 related autosomal recessive cerebellar ataxia type 1 (ARCA1) is a late-onset cerebellar ataxia with slow progression originally demonstrated in French-Canadian populations of Quebec, Canada. Nevertheless, recent studies on SYNE1 ataxia have conveyed the condition from a geographically limited pure cerebellar recessive ataxia to a complex multisystem phenotype that is relatively common on the global scale. To determine the underlying genetic cause of the ataxia phenotype in a consanguineous family from Turkey presenting with very slow progressive cerebellar symptoms including dysarthria, dysmetria, and gait ataxia, we performed SNP-based linkage analysis in the family along with whole exome sequencing (WES) in two affected siblings. We identified a homozygous variant in SYNE1 (NM_033071.3: c.13086delC; p.His4362GlnfsX2) in all four affected siblings. This variant presented herein has originally been associated with only pure ataxia in a single case. We thus present segregation and phenotypic manifestations of this variant in four affected family members and further extend the pure ataxia phenotype with upper motor neuron involvement and peripheral neuropathy. Our findings in turn established a precise molecular diagnosis in this family, demonstrating the use of WES combined with linkage analysis in families as a powerful tool for establishing a quick and precise genetic diagnosis of complex neurological phenotypes.

The frequency of C609T polymorphism in the NQO1 gene and its relation to cytogenetic abnormalities in patients with myelodysplastic syndrome.

The aim of the present study is to evaluate the frequency of C609T polymorphism in the NQO1 (NAD(P)H) quinon oxydoreductase) gene and its relation to cytogenetic abnormalities in patients with Myelodysplastic Syndrome (MDS). The study group consisted of 80 patients MDS with 13 of them in the pediatric age group. The frequency of the NQO1 gene polymorphism was compared with a healthy control group involving 423 individuals. Cytogenetic abnormalities were detected in 43 patients (54%). In patients with MDS the overall frequency of the C609T polymorphism was not different than controls. Also, although the frequency of the C609T polymorphism was higher in patients with secondary MDS (sMDS) (OR: 1.893, 95% CI: 0.840-4.265, p=0.238) , 5/del(5q) (OR:1.298, 95% CI: 0.331-5.086,p=0.124), +21(OR:1.817, 95% CI:0.429-7698,p=0.124) and t(8;21) (OR:3.028, 95% CI: 0.604-15.172,p=0.137) groups, the difference did not reach statistical significiance. Our results do not support the view that the C609T polymorphism has a role in the pathogenesis of MDS. Also the frequency of the C609T allele did not seem to be associated with cytogenetic abnormalities.

Evaluating CT Perfusion Deficits in Global Cerebral Edema after Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND AND PURPOSE: Global cerebral edema is an independent predictor of mortality and poor outcomes after aneurysmal SAH. Global cerebral edema, a complex disease process, is thought to be associated with an altered cerebral autoregulatory response. We studied the association between cerebral hemodynamics and early global cerebral edema by using CTP. MATERIALS AND METHODS: We retrospectively studied consecutive patients with aneurysmal SAH with admission CTP performed at days 0-3. Two neuroradiologists classified global cerebral edema and hydrocephalus on NCCT performed concurrently with CTP. Global cerebral edema was defined as diffuse effacement of the sulci and/or basal cisterns or diffuse disruption of the cerebral gray-white matter junction. CTP was postprocessed into CBF and MTT maps by using a standardized method. Quantitative analysis of CTP was performed by using standard protocol with ROI sampling of the cerebral cortex. The Fisher exact test, Mann-Whitney test, and independent-samples t test were used to determine statistical associations. RESULTS: Of the 45 patients included, 42% (19/45) had global cerebral edema and 58% (26/45) did not. Patient groups with and without global cerebral edema were well-matched for demographic and clinical data. Patients with global cerebral edema were more likely to have qualitative global CTP deficits than those without global cerebral edema (P = .001) with an OR = 13.3 (95% CI, 2.09-138.63). Patients with global cerebral edema also had a very strong trend toward statistical significance, with reduced quantitative CBF compared with patients without global cerebral edema (P = .064). CONCLUSIONS: Global perfusion deficits are significantly associated with global cerebral edema in the early phase after aneurysmal SAH, supporting the theory that hemodynamic disturbances occur in global cerebral edema.

A certified plasmid reference material for the standardisation of BCR-ABL1 mRNA quantification by real-time quantitative PCR.

Serial quantification of BCR-ABL1 mRNA is an important therapeutic indicator in chronic myeloid leukaemia, but there is a substantial variation in results reported by different laboratories. To improve comparability, an internationally accepted plasmid certified reference material (CRM) was developed according to ISO Guide 34:2009. Fragments of BCR-ABL1 (e14a2 mRNA fusion), BCR and GUSB transcripts were amplified and cloned into pUC18 to yield plasmid pIRMM0099. Six different linearised plasmid solutions were produced with the following copy number concentrations, assigned by digital PCR, and expanded uncertainties: 1.08±0.13 × 10(6), 1.08±0.11 × 10(5), 1.03±0.10 × 10(4), 1.02±0.09 × 10(3), 1.04±0.10 × 10(2) and 10.0±1.5 copies/µl. The certification of the material for the number of specific DNA fragments per plasmid, copy number concentration of the plasmid solutions and the assessment of inter-unit heterogeneity and stability were performed according to ISO Guide 35:2006. Two suitability studies performed by 63 BCR-ABL1 testing laboratories demonstrated that this set of 6 plasmid CRMs can help to standardise a number of measured transcripts of e14a2 BCR-ABL1 and three control genes (ABL1, BCR and GUSB). The set of six plasmid CRMs is distributed worldwide by the Institute for Reference Materials and Measurements (Belgium) and its authorised distributors (https://ec.europa.eu/jrc/en/reference-materials/catalogue/; CRM code ERM-AD623a-f).

Deregulated WNT signaling in childhood T-cell acute lymphoblastic leukemia.

WNT signaling has been implicated in the regulation of hematopoietic stem cells and plays an important role during T-cell development in thymus. Here we investigated WNT pathway activation in childhood T-cell acute lymphoblastic leukemia (T-ALL) patients. To evaluate the potential role of WNT signaling in T-cell leukomogenesis, we performed expression analysis of key components of WNT pathway. More than 85% of the childhood T-ALL patients showed upregulated ß-catenin expression at the protein level compared with normal human thymocytes. The impact of this upregulation was reflected in high expression of known target genes (AXIN2, c-MYC, TCF1 and LEF). Especially AXIN2, the universal target gene of WNT pathway, was upregulated at both mRNA and protein levels in ∼40% of the patients. When ß-CATENIN gene was silenced by small interfering RNA, the cancer cells showed higher rates of apoptosis. These results demonstrate that abnormal WNT signaling activation occurs in a significant fraction of human T-ALL cases independent of known T-ALL risk factors. We conclude that deregulated WNT signaling is a novel oncogenic event in childhood T-ALL.

Expression analysis and clinical correlation of aquaporin 1 and 4 genes in human hippocampal sclerosis.

Mesial temporal sclerosis (MTS) is the most frequent cause of drug resistant symptomatic partial epilepsy. The mechanism and genetic background of this unique pathology are not well understood. Aquaporins (AQP) are regulators of water homeostasis in the brain and are expressed in the human hippocampus. We explored the role of AQP genes in the pathogenetic mechanisms of MTS through an evaluation of gene expression in surgically removed human brain tissue. We analyzed AQP1 and 4 mRNA levels by quantitative real-time polymerase chain reaction and normalized to ABL and cyclophilin genes, followed by immunohistochemistry for AQP4. Relative expressions were calculated according to the delta Ct method and the results were compared using the Mann-Whitney U test. Brain specimens of 23 patients with epilepsy who had undergone surgery for MTS and seven control autopsy specimens were investigated. Clinical findings were concordant with previous studies and 61% of the patients were seizure-free in the postoperative period. AQP1 and 4 gene expression levels did not differ between MTS patients and control groups. Immunofluorescence analysis of AQP4 supported the expression results, showing no difference. Previous studies have reported contradictory results about the expression levels of AQP in MTS. To our knowledge, only one study has suggested upregulation whereas the other indicated downregulation of perivascular AQP4. Our study did not support these findings and may rule out the involvement of AQP in human MTS.

The role of MDR1 C3435T gene polymorphism on gingival hyperplasia in Turkish renal transplant patients treated with cyclosporine in the absence of calcium channel blockers.

OBJECTIVE: To investigate the occurrence of MDR1 C3435T gene polymorphisms in the Turkish renal transplant patients treated with cyclosporine (CsA), and correlate these findings with prevalence and degree of gingival hyperplasia (GH). METHODS: Before to renal transplantation, dental treatment and oral hygiene education of 300 renal disease patients was completed. Peripheral blood samples were collected from 154 renal transplant recipients on CsA treatment without calcium channel blockers. MDR1 C3435T gene polymorphism and GH were analyzed at posttransplant month 6. RESULTS: No difference was detected among groups for age, posttransplant period, creatine levels, serum concentration of CsA, or plaque and bleeding indices (P > .05). Out of all transplanted patients, 42.8% were found to have the heterozygote genotype. This was reduced to 37.5% when individuals with GH were taken into account. However, when degree of GH was analyzed, those with severe GH were found to have the heterozygote genotype significantly more often (P < .05). CONCLUSIONS: The MDR1 gene polymorphism is not associated with GH frequency, but may be associated with GH severity.

11ß-hydroxysteroid dehydrogenase type 1 gene expression is increased in ascending aorta tissue of metabolic syndrome patients with coronary artery disease.

11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD-1) activity and mRNA levels are increased in visceral and subcutaneous adipose tissues of metabolic syndrome subjects. We analyzed 11ß-HSD-1 expression in human epicardial adipose (EA) and ascending aorta (AA) tissues of metabolic syndrome patients and examined their contribution to the development of coronary atherosclerosis. The 11ß-HSD-1 expression was evaluated by qRT-PCR in EA and AA tissues of 20 metabolic syndrome patients with coronary artery disease (metabolic syndrome group) and 10 non-metabolic syndrome patients without coronary artery disease (controls). 11ß-HSD-1 expression was increased in EA and AA tissues of the metabolic syndrome group (4.1- and 5.5-fold, respectively). A significant positive correlation was found between 11ß-HSD-1 expression in EA tissue and waist hip ratio and 11ß-HSD-1 expression in AA tissue and body mass index, while a negative correlation was found between 11ß-HSD-1 expression in EA tissue and HDL. Expression of CD68, a macrophage marker, was significantly increased in both tissues of the metabolic syndrome group; it was 2-fold higher in AA tissue compared to EA tissue in the metabolic syndrome group. Our findings of increased expression of 11ß-HSD-1 and CD68 in AA tissue of the metabolic syndrome group lead us to suggest that they contribute to coronary atherosclerosis in metabolic syndrome. This positive correlation between obesity markers and 11ß-HSD-1 in AA and EA tissues strengthens the evidence that 11ß-HSD-1 has a role in metabolic syndrome. To the best of our knowledge, this is the first report showing 11ß-HSD-1 and CD68 expression in AA tissue of metabolic syndrome patients. We suggest that there is tissue-specific expression of 11ß-HSD-1 in metabolic syndrome and associated cardiovascular disorders.

Glutathione S-transferase P1 polymorphisms are associated with time to tumor progression in small cell lung cancer patients.

PURPOSE: Many of commonly used chemotherapeutics in lung cancer treatment are metabolized by glutathione-S transferases (GSTs). The placental isoform of GST (GSTP1) is the most abundant isoform in the lung. Polymorphisms within the GSTP1 may result in alterations in enzyme activity and change sensitivity to platinum-based chemotherapy. We investigated whether the polymorphism within the exons 5 and 6 of GSTP1 gene may change response to therapy, time to tumor progression (TTP) and overall survival in small cell lung cancer (SCLC) patients. METHODS: Ninety-four histologically confirmed patients with SCLC were enrolled in this study during 1995-2006. GSTP1 Ile105Val polymorphism in exon 5 and GSTP1 Ala- 114Val polymorphism in exon 6 were determined by using PCR-RFLP techniques. Associations between the GSTP1 polymorphisms and treatment response were evaluated using the chi-square test. Associations between the GSTP1 polymorphisms and TTP and overall survival were compared using Kaplan-Meier survival curves. RESULTS: We found no significant associations between exon 5 and exon 6 GSTP1 gene polymorphisms and response to therapy or overall survival. Patients carrying both variant exon 5 (Ile/Val or Val/Val) and variant exon 6 (Ala/Val) genotypes had significantly shorter TTP (5 vs. 8 months, p = 0.04). Moreover, patients with heterozygote exon 6 variant had presented with extensive-stage disease. CONCLUSION: No individual effect of variant alleles was found in relation to chemotherapy response, median TTP and overall survival. The carriage of both types of variant alleles may predict worse outcome.

Development of standardized approaches to reporting of minimal residual disease data using a reporting software package designed within the European LeukemiaNet.

Quantitative PCR (qPCR) for detection of fusion transcripts and overexpressed genes is a promising tool for following minimal residual disease (MRD) in patients with hematological malignancies. Its widespread clinical use has to some extent been hampered by differences in data analysis and presentation that complicate multicenter clinical trials. To address these issues, we designed a highly flexible MRD-reporting software program, in which data from various qPCR platforms can be imported, processed, and presented in a uniform manner to generate intuitively understandable reports. The software was tested in a two-step quality control (QC) study; the first step involved eight centers, whose previous experience with the software ranged from none to extensive. The participants received cDNA from consecutive samples from a BCR-ABL+ chronic myeloid leukemia (CML) patient and an acute myeloid leukemia (AML) patient with both CBFß-MYH11 and WT1 target genes, they conducted qPCR on their respective hardware platforms and generated a series of reports with pre-defined features. In step two, five centers used the software to report BCR-ABL+ MRD in a harmonized manner, applying their recently obtained CML international scale conversion factors. The QC study demonstrated that this MRD-reporting software is suitable for efficient handling of qPCR data, generation of MRD reports and harmonization of MRD data.

Validation of breast cancer nomograms for predicting the non-sentinel lymph node metastases after a positive sentinel lymph node biopsy in a multi-center study.

OBJECTIVE: In the study, our aim was to evaluate the predictability of four different nomograms on non-sentinel lymph node metastases (NSLNM) in breast cancer (BC) patients with positive sentinel lymph node (SLN) biopsy in a multi-center study. METHODS: We identified 607 patients who had a positive SLN biopsy and completion axillary lymph node dissection (CALND) at seven different BC treatment centers in Turkey. The BC nomograms developed by the Memorial Sloan Kettering Cancer Center (MSKCC), Tenon Hospital, Cambridge University, and Stanford University were used to calculate the probability of NSLNM. Area under (AUC) Receiver Operating Characteristics Curve (ROC) was calculated for each nomogram and values greater than 0.70 were accepted as demonstrating good discrimination. RESULTS: Two hundred and eighty-seven patients (287) of 607 patients (47.2%) had a positive axillary NSLNM. The AUC values were 0.705, 0.711, 0.730, and 0.582 for the MSKCC, Cambridge, Stanford, and Tenon models, respectively. On the multivariate analysis; overall metastasis size (OMS), lymphovascular invasion (LVI), and proportion of positive SLN to total SLN were found statistically significant. We created a formula to predict the NSLNM in our patient population and the AUC value of this formula was 0.8023. CONCLUSIONS: The MSKCC, Cambridge, and Stanford nomograms were good discriminators of NSLNM in SLN positive BC patients in this study. A newly created formula in this study needs to be validated in prospective studies in different patient populations. A nomogram to predict NSLNM in patients with positive SLN biopsy developed at one institution should be used with caution.

Seroreactivity against PTEN-induced putative kinase 1 (PINK1) in Turkish patients with Behçet's disease.

BACKGROUND: Behçet's disease (BD) is a multisystem inflammatory disorder characterized by recurrent oral ulcers, genital ulcers and ocular inflammation, as well as skin, joint, vascular, pulmonary, central nervous system (CNS) and gastrointestinal tract manifestations. The etiopathogenesis of BD has not yet been identified; but it has generally been accepted that several environmental factors may induce an inflammatory attack in genetically susceptible individuals. In this study, we aimed to identify antigens that could elicit high-titer IgG responses by the serological analysis of recombinant expression of cDNA libraries method (SEREX). METHODS: We screened a human testis cDNA library with pooled sera obtained from 4 BD patients by SEREX. Antigens that were identified with the initial analysis were selected for seroreactivity analysis of a larger group of BD patients (n=78) and controls (n=66) by serological immunoscreening. RESULTS: We observed seroreactivity against 6 antigens using the pooled sera. These included rabaptin 5 (RABPT5), PTEN-induced putative kinase 1 (PINK1), switch associated protein 70 (SWAP70), interferon-induced protein with tetratricopeptide repeats 2 (IFIT2), ankyrin repeat domain 20 family, member A1 (ANKRD20A1), and an unknown antigen. Eleven out of 82 (13.4%) BD patients were found to have antibodies elicited against PINK1 antigen, when none of the control sera showed reactivity (p=0.001). There was no significant difference in the frequency of other defined antigens between the patient and control groups. However, among BD clinical sub-groups, anti-SWAP70 antibodies were found to associate with vascular involvement. DISCUSSION: In this study, antibodies against PINK1 were found to specifically associate with BD while SWAP70 antibody was associated with clinical sub-groups of BD. Although variations in both genetic background and environmental factors may affect the outcome of serological responses, our results suggest that serological screening can be used to identify antigens that elicit antibody responses associated with BD.

Effects of imatinib mesylate on renin-angiotensin system (RAS) activity during the clinical course of chronic myeloid leukaemia.

The renin-angiotensin system (RAS) is involved in cell growth, proliferation and differentiation in bone marrow in an autocrine-paracrine manner, and it modulates normal and neoplastic haematopoietic cell proliferation. This study aimed to assess expressions of the RAS components, renin, angiotensinogen and angiotensin-converting enzyme (ACE), during imatinib mesylate treatment of patients with chronic myeloid leukaemia (CML). Expressions of RAS components were studied in patients with CML at the time of diagnosis (n = 83) and at 3, 6 and 12 months after diagnosis (n = 35) by quantitative real-time polymerase chain reaction. De novo CML patients had increased ACE, angiotensinogen and renin mRNA levels and these expression levels decreased following administration of imatinib. The RAS activities were significantly different among Sokal risk groups of CML, highlighting the altered biological activity of RAS in neoplastic disorders. The results of this study confirm that haematopoietic RAS affects neoplastic cell production, which may be altered via administration of tyrosine kinase inhibitors such as imatinib mesylate.

Which anesthetic agent alters the hemodynamic status during pediatric catheterization? Comparison of propofol versus ketamine.

OBJECTIVE: To compare the effects of propofol and ketamine on systemic and pulmonary circulations in pediatric patients scheduled for elective cardiac catheterization. DESIGN: Prospective, randomized, and blinded. SETTING: University hospital. PARTICIPANTS: Children (n = 41) undergoing cardiac catheterization. INTERVENTIONS: All children were premedicated with oral midazolam 60 minutes before the procedure. Patients were separated into 3 groups according to shunts diagnosed by transthoracic echocardiography before the catheterization procedure: patients without cardiac shunt (Group I, n = 11), left-to-right shunt (Group II, n = 12), and right-to-left shunt (Group III, n = 18). A continuous infusion of propofol (100-200 microg/kg/min) or ketamine (50-75 microg/kg/min) was randomly started in all groups to obtain immobility during the procedure. Hemodynamic data, including systemic venous, pulmonary artery and vein, aortic saturations and pressures, were recorded; Qp/Qs were calculated. The same set of data was recorded before discontinuation of infusions at the end of the procedure. MEASUREMENTS AND MAIN RESULTS: After the propofol administration, in all 3 patient groups propofol infusion was associated with significant decreases in systemic mean arterial pressure. In groups with cardiac shunts (Group II and III), propofol infusion significantly decreased systemic vascular resistance and increased systemic blood flow, whereas pulmonary vascular resistance and pulmonary blood flow did not change significantly. These changes resulted in decreased left-to-right shunting and increased right-to-left shunting; the pulmonary-to-systemic flow ratio decreased significantly. On the other hand, after ketamine infusion, systemic mean arterial pressure increased significantly in all patient groups, but pulmonary mean arterial pressure, systemic vascular resistance, and pulmonary vascular resistance were unchanged. CONCLUSION: In children with cardiac shunting, the principal hemodynamic effect of propofol is a decrease in systemic vascular resistance. In children with intracardiac shunting, this results in an increase in right-to-left shunting and a decrease in the ratio of pulmonary to systemic blood flow, which may lead to arterial desaturation. Ketamine did not produce these changes. The authors suggested that during cardiac catheterization in children, both the anesthesiologists and cardiologists need to know that anesthetic agents can significantly alter the hemodynamic status in children with complex congenital heart defects and affect the results of hemodynamic calculations that are important for decision-making and treatment of these patients.

Concurrent methylation of multiple genes in childhood ALL: Correlation with phenotype and molecular subgroup.

Multiple genes have been shown to be independently hypermethylated in lymphoid malignancies. We report here on the extent of concurrent methylation of E-cadherin, Dap-kinase, O(6)MGMT, p73, p16, p15 and p14 in 129 pediatric ALL cases. While most of these genes demonstrated methylation in a proportion of cases, O(6)MGMT, p16 and p14 were infrequently methylated (11, 7 and 3%, respectively). Methylation of at least one gene was found in the vast majority (83%) of cases. To determine the extent and concordance of methylation we calculated a methylation index (MI=number of methylated genes/number of studied genes) for each sample. The average MI was 0.28, corresponding to 2/7 methylated genes. MI was correlated with standard prognostic factors, including immunophenotype, age, sex, WBC and presence of specific translocations (TEL-AML1, BCR-ABL, E2A-PBX1 or MLL-AF4). We determined that children >/=10 years old and children presenting with high WBC (>/=50 x 10(9)/l) both associated with a higher MI (P<0.01 and <0.05, respectively). T-ALLs demonstrated a lower MI (median=0.17) than precursor B ALLs (median=0.28). Among the different molecular subgroups, MLL-ALLs had the highest MI (mean=0.35), while ALLs carrying the t(1;19) had the lowest MI (mean=0.07). The most common epigenetic lesion in childhood ALL was methylation of E-cadherin (72%) independent of the molecular subtype or other clinicopathological factors.

Tumour necrosis factor-alpha gene promoter region -308 and -376 G-->A polymorphisms in Behçet's disease.

OBJECTIVE: Contribution of HLA-B51 to the genetic susceptibility for Behçet's disease is well documented and recent studies suggest involvement of other genes. Tumour necrosis factor (TNF) genes are located in the vicinity of the HLA-B locus. Polymorphisms in the promoter region of TNF-alpha gene has been found to be associated with altered TNF secretion, and it may have a prominent role in the increased inflammatory responses of Behçet's disease. METHODS: The study group consisted of 99 Behçet's disease patients and 96 healthy matched controls. All patients fulfilled the International Study Group criteria for Behçet's disease. The TNF-alpha -308 and -376 promoter alleles were assigned by the digestion of each amplified PCR product with NcoI and TasI enzymes, respectively. RESULTS: No significant difference was observed in the distribution of TNF-alpha promoter region polymorphisms between patients with Behçet's disease and controls. There was no association between the presence of uncommon -308A and -376A alleles and the manifestations or severity of Behçet's disease either. The TNF-alpha -308A allele and HLA-B*50 was found to be associated in this series of Turkish patients and controls. CONCLUSION: The role of TNF-alpha promoter region -308 and -376 polymorphisms in the pathogenesis of Behçet's disease is not supported by this data. The overexpression of TNF-alpha in Behçet's disease may be caused by other polymorphisms in the TNF gene or by post-transcriptional mechanisms.

Genetic polymorphism of cytochrome P450 2E1 in the Turkish population.

CYP 2E1 is involved in metabolic activation of carcinogenic N-nitrosamines, benzene, urethane and other low molecular weight compounds. CYP2E1 gene is present in the population in various polymorphic forms. We detected the RFLP of the human CYP2E1 gene with the restriction endonuclease PstI, RsaI and DraI in a group of 153 Turkish individuals. According to the results of the PstI/RsaI analysis, 96.07% of the subjects were of the c1/c1 genotype, and 3.93% were of the c1/c2 genotype. In the DraI RFLP analysis, 84.30% DD genotype, 15.03% CD genotype and 0.66% CC genotype were determined. The data obtained may be useful in epidemiological studies of the influence of CYP2E1 polymorphism on carcinogenesis.

Activated Protein C Resistance in Polycythemia Vera.

Activated protein C resistance is a result of a point mutation in factor V gene (Leiden mutation) and can be identified in approximately 50% of patients with thrombosis, making it an important risk factor for thrombosis. The aim of this study is to evaluate the role activated protein C resistance in the hypercoagulable state seen in polycythemia vera. We compared patients with polycythemia vera (n: 24) for increased risk of thromboembolism and activated protein C resistance, with the results of patients with chronic myelogenous leukemia (n: 27) and healthy control group (n: 52). Activated protein C resistance test and factor VIII activity was determined by an aPTT based test. Anticardiolipin antibodies IgG and IgM were also determined by ELISA. Leiden mutation was studied with polymerase chain reaction. Venous thromboses were observed in 12.5% and arterial thromboses in 41.6% of patients with polycythemia vera. Arterial thromboses were recognized in 7.4% of patients with chronic myelogenous leukemia. Activated protein C resistance was identified in 20.8% of patients with polycythemia vera and 14.8% with chronic myelogenous leukemia (versus 1.8% of healthy control subjects). The risk of thrombosis in patients with polycythemia vera was independent from the presence of activated protein C resistance. Leiden mutation was observed in only 1 patient out of 4 patients with chronic myelogenous leukemia who had activated protein C resistance, but not thrombosis. Factor VIII levels of patients with chronic myelogenous leukemia (158% ± 14) were higher than healthy control subjects (99% ± 15) (p< 0.05). Patients with activated protein C resistance in both groups had no seropositivity for anticardiolipin antibodies IgG and IgM. Activated protein C resistance and in some cases its association with Leiden mutation in polycythemia vera may not have a major role in the pathogenesis of thromboembolic complications of polycythemia vera.

Is AML1/ETO gene expression a good prognostic factor in pediatric acute myeloblastic leukemia?

To assess the clinical significance of AML1/ETO gene detected by nested reverse transcriptase polymerase chain reaction, the outcome of 7 patients with acute myeloblastic leukemia between 3 and 14 years of age were presented. All patients had complete remission (CR) at the end of induction (AML-MRC 10 protocol) and 4 underwent unpurged autologous, 2 allogeneic (from matched siblings) non-T-cell-depleted bone marrow transplantations (BMT) in first CR. One patient died due to allogeneic BMT-related complications, and 4 patients relapsed at 13, 17, 18, and 26 months. Only one patient achieved second CR. All relapsed patients died between 18 and 36 months with resistant disease (n = 3) or infection during salvage chemotherapy (n = 1). Two patients who had autologous BMT are alive and disease free at 44 and 50 months. Although statistical significance could not be shown, event-free survival and overall survival rates of AML1/ETO-positive patients (28.57 and 28.57%, respectively) at 3.5 years were even lower than those of AML1/ETO-negative patients. The results confirm some previous reports that AML1/ETO gene in children and adolescents is not a favorable prognostic factor.