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Maternal folate genes and aberrant DNA hypermethylation in pediatric acute lymphoblastic leukemia.

ABSTRACT: Background: There is evidence that maternal genotypes in folate-related genes are associated with pediatric acute lymphoblastic leukemia (ALL) independent of offspring genotype. We evaluated the relationship between maternal genotypes in methionine synthase (MTR) and DNA methylation status in ALL to better characterize the molecular mechanism underlying this association.

Procedure: We obtained bone marrow samples from 51 patients with ALL at diagnosis and from 6 healthy donors. Mothers of patients provided a saliva sample and were genotyped at 11 tagSNPs in MTR. DNA methylation was measured in bone marrow mononuclear cells of patients and six healthy marrow donors. We used hierarchical clustering to identify patients with a hypermethylator phenotype based on 281 differentially methylated promoter CpGs. We used logistic regression to estimate the effects of maternal genotype on the likelihood of DNA hypermethylation in ALL and Ingenuity Pathway Analysis to identify networks enriched for differentially methylated genes.

Results: Twenty-two cases (43%) demonstrated promoter hypermethylation, which was more frequent among those with ETV6-RUNX1 fusion and initial white blood cell count < 50 x 109/L. Maternal rs12759827 was associated with aberrant DNA methylation (odds ratio [OR] 4.67, 95% confidence interval 1.46-16.31); non-significantly elevated ORs were observed for all other SNPs. Aberrantly methylated promoter CpGs aligned to genes with known cancer-related functions.

Discussion: Maternal folate metabolic genotype may be associated with DNA methylation patterns in ALL in their offspring. Therefore, the effect of maternal genotypes on ALL susceptibility may act through aberrant promoter methylation, which may contribute to the in utero origins of ALL.

SUBMITTER: Schraw JM

PROVIDER: S-EPMC5953491 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Maternal folate genes and aberrant DNA hypermethylation in pediatric acute lymphoblastic leukemia.

Schraw Jeremy M JM Yiu Teresa T TT Lupo Philip J PJ Tsavachidis Spiridon S Rau Rachel R Bondy Melissa L ML Rabin Karen R KR Shen Lanlan L Scheurer Michael E ME

PloS one 20180515 5

<h4>Background</h4>There is evidence that maternal genotypes in folate-related genes are associated with pediatric acute lymphoblastic leukemia (ALL) independent of offspring genotype. We evaluated the relationship between maternal genotypes in methionine synthase (MTR) and DNA methylation status in ALL to better characterize the molecular mechanism underlying this association.<h4>Procedure</h4>We obtained bone marrow samples from 51 patients with ALL at diagnosis and from 6 healthy donors. Moth ...[more]

PMID: 29763473

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Project description:We present a method that utilizes DNA methylation profiling for prediction of the cytogenetic subtypes of acute lymphoblastic leukemia (ALL) cells from pediatric ALL patients. The primary aim of our study was to improve risk stratification of ALL patients into treatment groups using DNA methylation as a complement to current diagnostic methods. A secondary aim was to gain insight into the functional role of DNA methylation in ALL.We used the methylation status of ~450,000 CpG sites in 546 well-characterized patients with T-ALL or seven recurrent B-cell precursor ALL subtypes to design and validate sensitive and accurate DNA methylation classifiers. After repeated cross-validation, a final classifier was derived that consisted of only 246 CpG sites. The mean sensitivity and specificity of the classifier across the known subtypes was 0.90 and 0.99, respectively. We then used DNA methylation classification to screen for subtype membership of 210 patients with undefined karyotype (normal or no result) or non-recurrent cytogenetic aberrations ('other' subtype). Nearly half (n?=?106) of the patients lacking cytogenetic subgrouping displayed highly similar methylation profiles as the patients in the known recurrent groups. We verified the subtype of 20% of the newly classified patients by examination of diagnostic karyotypes, array-based copy number analysis, and detection of fusion genes by quantitative polymerase chain reaction (PCR) and RNA-sequencing (RNA-seq). Using RNA-seq data from ALL patients where cytogenetic subtype and DNA methylation classification did not agree, we discovered several novel fusion genes involving ETV6, RUNX1, and PAX5.Our findings indicate that DNA methylation profiling contributes to the clarification of the heterogeneity in cytogenetically undefined ALL patient groups and could be implemented as a complementary method for diagnosis of ALL. The results of our study provide clues to the origin and development of leukemic transformation. The methylation status of the CpG sites constituting the classifiers also highlight relevant biological characteristics in otherwise unclassified ALL patients.

Dataset Information

Maternal folate genes and aberrant DNA hypermethylation in pediatric acute lymphoblastic leukemia.

Publications

Maternal folate genes and aberrant DNA hypermethylation in pediatric acute lymphoblastic leukemia.

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