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Vincristine is an important drug of acute lymphoblastic leukemia (ALL) treatment protocols that can cause neurotoxicity. Patients treated with LAL/SHOP protocols often suffer from vincristine-related neurotoxicity in early phases of treatment. A genetic variant in CEP72, a gene involved in vincristine pharmacodynamics, was recently associated with neurotoxicity after prolonged vincristine treatment. This association was not replicated in our Spanish population during induction phase. To test the possibility that other variants in genes involved in vincristine pharmacodynamics were associated with vincristine neuropathy in early phases of the treatment, we evaluated the correlation with toxicity of 24 polymorphisms in 9 key genes in a large cohort of 152 Spanish children with B-ALL homogeneously treated. Results showed no association between any genetic variant in the TUBB1, TUBB2A, TUBB2B, TUBB3, TUBB4, MAPT, MIR146a, MIR202, and MIR411 genes and vincristine-related neurotoxicity. These results are in line with the hypothesis that there are different mechanisms causing pheripheral neurotoxicity after prolonged and short-term vincristine treatments.

Vincristine (VCR), an important component of childhood acute lymphoblastic leukemia (ALL) therapy, can cause sensory and motor neurotoxicity. This neurotoxicity could lead to dose reduction or treatment discontinuation, which could in turn reduce survival. In this line, several studies associated peripheral neurotoxicity and polymorphisms in genes involved in pharmacokinetics (PK) and pharmacodynamics (PD) of VCR. Nowadays, it is well known that these genes are regulated by microRNAs (miRNAs) and SNPs in miRNAs could modify their levels or function. Therefore, the aim of this study was to determine whether SNPs in miRNAs could be associated with VCR-induced neurotoxicity. To achieve this aim, we analyzed all the SNPs in miRNAs (minor allele frequency (MAF) ≥ 0.01) which could regulate VCR-related genes in a large cohort of Spanish children with B-cell precursor ALL (B-ALL) homogeneously treated with LAL/SHOP protocols. We identified the A allele of rs12402181 in the seed region of miR-3117-3p, that could affect the binding with ABCC1and RALBP1gene, and C allele of rs7896283 in pre-mature sequence of miR-4481, which could be involved in peripheral nerve regeneration, significantly associated with VCR-induced neurotoxicity. These findings point out the possible involvement of two SNPs in miRNA associated with VCR-related neurotoxicity.

Aim:Mucositis, linked to methotrexate, daunorubicin or cyclophosphamide, is a frequent childhood acute lymphoblastic leukemia (ALL) therapy side effect. miRNAs regulate the expression of pharmacokinetic/pharmacodynamic pathway genes. SNPs in miRNAs could affect their levels or function, and affect their pharmacokinetic/pharmacodynamic pathway target genes. Our aim was to determine the association between miRNA genetic variants targeting mucositis-related genes and mucositis-developing risk. Patients & methods:We analyzed 160 SNPs in 179 Spanish children with B-cell precursor ALL homogeneously treated with LAL/SHOP protocols. Results:We identified three SNPs in miR-4268, miR-4751 and miR-3117 associated with mucositis, diarrhea and vomiting, respectively. Conclusion:The effect of these SNPs on genes related to drug pharmacokinetics/pharmacodynamics could explain mucositis, diarrhea and vomiting development during ALL therapy.

Childhood acute lymphoblastic leukemia survival rates have increased remarkably during last decades due, in part, to intensive treatment protocols. However, therapy resistance and toxicity are still two important barriers to survival. In this context, pharmacoepigenetics arises as a tool to identify new predictive markers, required to guide clinicians on risk stratification and dose individualization. The present study reviews current evidence about miRNA implication on childhood acute lymphoblastic leukemia therapy resistance and toxicity. A total of 12 studies analyzing differential miRNA expression in relation to drug resistance and six studies exploring the association between miRNAs-related SNPs and drug-induced toxicities were identified. We pointed out to miR-125b together with miR-99a and/or miR-100 overexpression as markers of vincristine resistance and rs2114358 in mir-1206 as mucositis marker as the most promising results.

Acute lymphoblastic leukemia (ALL) is a major pediatric cancer in developed countries. Although treatment outcome has improved owing to advances in chemotherapy, there is still a group of patients who experience severe adverse events. L-Asparaginase is an effective antineoplastic agent used in chemotherapy of ALL. Despite its indisputable indication, hypersensitivity reactions are common. In those cases, discontinuation of treatment is usually needed and anti-asparaginase antibody production may also attenuate asparaginase activity, compromising its antileukemic effect. Till now, six pharmacogenetic studies have been performed in order to elucidate possible genetic predisposition for inter-individual differences in asparaginase hypersensitivity. In this review we have summarized the results of those studies which describe the involvement of four different genes, being polymorphisms in the glutamate receptor, ionotropic, AMPA 1 (GRIA1) the most frequently associated with asparaginase hypersensitivity. We also point to new approaches focusing on epigenetics that could be interesting for consideration in the near future.

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Two polymorphisms in the murine double minute 2 (MDM2) gene (rs1690916 and rs2279744) have been associated with the risk of osteosarcoma (OS). When we analyzed these two polymorphisms in two new independents cohorts (Spanish and Slovenian), we found no association. In order to clarify this, we conducted a meta-analysis including six populations, with a total of 246 OS patients and 1,760 controls for rs1690916; and 433 OS patients and 1,959 controls for rs2279744. Pooled odds ratio risks and corresponding 95% CI were estimated to assess the possible associations. Our results showed that these two polymorphisms were not associated with the susceptibility of OS under any genetic model studied. In conclusion, the present meta-analysis indicates that MDM2 rs1690916 and rs2279744 cannot be considered as genetic risk factors for OS susceptibility in the different populations. Therefore, the influence of these two polymorphisms on the risk of OS may be less important than previously suggested. Future studies are needed to confirm these results.

Aim:Vincristine is an important component of acute lymphoblastic leukemia (ALL) treatment protocols that can cause neurotoxicity. Patients treated with LAL/SHOP protocols often suffer from vincristine-related neurotoxicity in early phases of treatment. Recently, a genome-wide association study connected a SNP in CEP72, involved in vincristine pharmacodynamics, with neurotoxicity during later phases of therapy, which was not replicated during induction phase. These results, together with previous studies indicating that polymorphisms in pharmacokinetic genes are associated with drug toxicity, suggest that changes in the activity or levels of vincristine transporters or metabolizers could work as predictors of vincristine-related neurotoxicity in early phases of treatment in pediatric ALL. Patients & methods:We analyzed 150 SNPs in eight key genes involved in vincristine pharmacokinetics and in 13 miRNAs that regulate them. We studied their correlation with neurotoxicity during induction phase in 152 ALL patients treated with LAL/SHOP protocols. Results:The strongest associations with neurotoxicity were observed for two SNPs in ABCC2. The genotypes rs3740066 GG and rs12826 GG were associated with increased neurotoxicity. Conclusion:Polymorphisms in ABCC2could be novel markers for vincristine-related neurotoxicity in pediatric ALL in early phases.

Background:Evidence for an inherited genetic risk for pediatric acute lymphoblastic leukemia has been provided in several studies. Most of them focused on coding regions. However, those regions represent only 1.5% of the entire genome. In acute lymphoblastic leukemia (ALL), it has been suggested that the expression of microRNAs (miRNAs) is dysregulated, which suggests that they may have a role in ALL risk. Changes in miRNA function may occur through single-nucleotide polymorphisms (SNPs). Therefore, the aim of this study was to evaluate whether polymorphisms in pre-miRNAs, and/or miRNA-processing genes, contribute to a predisposition for childhood ALL.Methods:In this study, we analyzed 118 SNPs in pre-miRNAs and miRNA-processing genes in 213 B-cell ALL patients and 387 controls.Results:We found 11 SNPs significantly associated with ALL susceptibility. These included three SNPs present in miRNA genes (miR-612, miR-499, and miR-449b) and eight SNPs present in six miRNA biogenesis pathway genes (TNRC6B, DROSHA, DGCR8, EIF2C1, CNOT1, and CNOT6). Among the 118 SNPs analyzed, rs12803915 in mir-612 and rs3746444 in mir-499 exhibited a more significant association, with a P value <0.01.Conclusion:The results of this study indicate that SNP rs12803915 located in pre-mir-612, and SNP rs3746444 located in pre-mir-499, may represent novel markers of B-cell ALL susceptibility.

Methotrexate (MTX) is an important component of therapy for pediatric acute lymphoblastic leukemia (ALL). Treatment with MTX often causes toxicity, which can necessitate dose reduction or treatment cessation. Interindividual differences in adverse reactions can be due to different factors, including polymorphisms in key genes. Recently, we confirmed the association between SLCO1B1rs11045879 polymorphism and toxicity previously proposed by Treviño and colleagues. As SLCO1B1 is a transporter involved in MTX elimination, other polymorphisms in genes from this pathway could also have a role in MTX toxicity. The aim of the present study was to analyze in depth the role of polymorphisms in the genes of the MTX transport pathway as putative toxicity predictors in pediatric ALL.

Vincristine is a component of acute lymphoblastic leukemia (ALL) treatment with the potential to induce peripheral neuropathy. Recently, the CEP72rs924607 TT genotype was found to be associated with vincristine-induced toxicity during the continuation phase in pediatric ALL patients treated on the Total XIIIB and COG AALL0433 protocols at St Jude Children’s Research Hospital and Children’s Oncology Group. This finding could provide a base for safer dosing of vincristine. Nevertheless, there are variations in vincristine regimens among ALL treatment protocols and phases in different populations. Therefore, the aim of this study was to determine whether the CEP72rs924607 TT genotype is a useful marker of vincristine neuropathy during induction therapy among Spanish children with B-ALL treated on the LAL-SHOP protocols. No association was found between neurotoxicity during the induction phase and the rs924607 TT genotype. This lack of association could be because of population differences and/or differences in neurotoxicity etiology between induction and continuation phases of treatment.

Undiagnosed individuals with celiac disease (CD) or those who do not comply with gluten-free diet (GFD) are at a higher risk of developing malignancies. A possible origin of chromosomal alteration in autoimmune reaction could be mistakes in the rearrangement of V(D)J of the IgH gene. Our aim was to verify whether higher genomic instability was found in coeliac individuals and whether GFD reduced it. As marker of genomic instability we analysed the frequency of 2 translocations, t(14;18) and t(11;14), in peripheral blood by nested PCR, in 37 patients with CD at diagnosis, 27 patients with CD after 2 years on GFD, and 36 control individuals. No significant differences were found.

Undiagnosed individuals with celiac disease (CD) or those who do not comply with gluten-free diet (GFD) are at a higher risk of developing malignancies. A possible origin of chromosomal alteration in autoimmune reaction could be mistakes in the rearrangement of V(D)J of the IgH gene. Our aim was to verify whether higher genomic instability was found in coeliac individuals and whether GFD reduced it. As marker of genomic instability we analysed the frequency of 2 translocations, t(14;18) and t(11;14), in peripheral blood by nested PCR, in 37 patients with CD at diagnosis, 27 patients with CD after 2 years on GFD, and 36 control individuals. No significant differences were found.

Inferences about the role and location of phosphorylated histone H3 are derived primarily from biochemical studies. A few direct observations at chromosome level have shown that phosphorylation begins at the site of heterochromatin and spreads throughout the chromosome. However, a comparative study of chromosomes of mouse (L929 cells), Chinese hamster (CHO 9 cells) and the Indian muntjac (male cells) reveals some distinguishable details among mammalian species. Whereas the L929 cells exhibit the typical pattern of phosphorylation at the region of centromeric heterochromatin associated with the active centromere, the heterochromatin blocks associated with the inactive centromeres also show label of about equivalent intensity. Throughout the cell cycle, heterochromatin exhibits sharper (denser) and better defined label than does euchromatin which expresses somewhat diffuse label. The centromere constriction on biarmed chromosomes, originating in Robertsonian translocations, appears phosphorylated in some, if not all chromosomes. A similar situation was found for the CHO 9 cells indicating that phosphorylation does include the region in which H3 is supposedly replaced by CENP-A. An interesting feature of the CHO cell line was the dense label at and near the telomeres; this feature was not observed in either the mouse or the Indian muntjac. The centromere regions of the Indian muntjac chromosomes showed three sites of label in the multicentric X chromosome and two each on chromosome pair number 1 and Y2; the sites coinciding with the reaction sites of antikinetochore antibodies. Also, the X and Y1chromosomes of Indian muntjac show intense phosphorylation at the sites of secondary constrictions. The chromosomes of all three species were phosphorylated throughout the cell cycle. As the chromosomes started to decondense during anaphase, heavy phosphorylation was observed in the form of discontinuous beaded structures indicating partial despiralization of the chromosome. Interestingly, when cells had completed karyokinesis and resolved into two independent nuclei, the phosphorylation was observed at the midbody. At this stage, the cytoplasm appeared to be again phosphorylated.

The tetrameric STRs, HUMTH01, HUMVWA31A and HUMFES/FPS, were studied in a population from the Basque Country (northern Spain) for their frequency distribution and applicability to identity and paternity testing. All systems conformed to Hardy-Weinberg equilibrium; pairwise comparisons demonstrated the allelic independence between loci, and furthermore, all systems seemed to be in agreement with expectations from the Stepwise Mutation Model (SMM) of the mutation-drift theory, which indicates the homogeneity of the population and suggests a replication slippage mechanism as a possible model for generating alleles. A comparison with other population groups appeared to indicate that frequencies are well conserved in Caucasians, but differ from other racial groups. The calculated parameters “a priori probability of exclusion” (PEX) and “index of discrimination” (ID), show the informativeness of these loci for the determination of identity and relatedness of individuals.

No relevant conflicts of interest to declare.

Introduction:Methotrexate (MTX) is an important and effective chemotherapeutic drug in the treatment of pediatric acute lymphoblastic leukemia (ALL). However MTX can induce toxicity, which can lead to amendments of treatment and subsequent impaired survival. The aim of this study was to identify metabolic and genetic determinants of MTX toxicity.