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Although recent studies have demonstrated associations between nonchromosomal birth defects and several pediatric cancers, less is known about their role on childhood leukemia susceptibility. Using data from the Childhood Cancer and Leukemia International Consortium, we evaluated associations between nonchromosomal birth defects and childhood leukemia. Pooling consortium data from 18 questionnaire-based and three registry-based case-control studies across 13 countries, we used multivariable logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between a spectrum of birth defects and leukemia. Our analyses included acute lymphoblastic leukemia (ALL, n = 13 115) and acute myeloid leukemia (AML, n = 2120) cases, along with 46 172 controls. We used the false discovery rate to account for multiple comparisons. In the questionnaire-based studies, the prevalence of birth defects was 5% among cases vs 4% in controls, whereas, in the registry-based studies, the prevalence was 11% among cases vs 7% in controls. In pooled adjusted analyses, there were several notable associations, including (1) digestive system defects and ALL (OR = 2.70, 95% CI: 1.46-4.98); (2) congenital anomalies of the heart and circulatory system and AML (OR = 2.86, 95% CI: 1.81-4.52) and (3) nervous system defects and AML (OR = 4.23, 95% CI: 1.50-11.89). Effect sizes were generally larger in registry-based studies. Overall, our results could point to novel genetic and environmental factors associated with birth defects that could also increase leukemia susceptibility. Additionally, differences between questionnaire- and registry-based studies point to the importance of complementary sources of birth defect phenotype data when exploring these associations.

We thank Catherine Hill for her comments (1) on our recent study (2) on the association between residential proximity to viticultural areas and childhood acute leukemia risk in mainland France. [...]

Background: Prenatal folate supplementation has been consistently associated with a reduced risk of childhood lymphoblastic leukemia (ALL). Previous germline genetic studies examining the one carbon (folate) metabolism pathway were limited in sample size, scope, and population diversity, and led to inconclusive results., Methods: We evaluated whether ~2,900 single nucleotide polymorphisms (SNPs) within 46 candidate genes involved in the folate metabolism pathway influence the risk of childhood ALL, using genome-wide data from nine case-control-studies in the Childhood Cancer and Leukemia International Consortium (n=9,058 cases including 4,510 children of European ancestry, 3,018 Latinx, and 1,406 Asians, and 92,364 controls). Each study followed a standardized protocol for quality control and imputation of genome-wide data, and summary statistics were meta-analyzed for all children combined and by major ancestry group using METAL software., Results: None of the selected SNPs reached statistical significance, overall and for major ancestry groups (using adjusted Bonferroni p-value of 5x10-6 and less stringent p-value of 3.5x10-5 accounting for the number of "independent" SNPs). None of the 10 top (non-significant) SNPs and corresponding genes overlapped across ancestry groups., Conclusion: This large meta-analysis of original data does not reveal associations between many common genetic variants in the folate metabolism pathway and childhood ALL in various ancestry groups., Impact: Genetic variants in the folate pathway alone do not appear to substantially influence childhood ALL risk. Other mechanisms such as gene-folate interaction, DNA methylation or maternal genetic effects may explain the observed associations with self-reported prenatal folate intake.