OBJECTIVETo evaluate the association between chemical exposure, DNA methylation status and gene-environment interactions in the development of childhood acute leukemia (AL).

METHODSFrom January 1st 2009 to December 31st 2010, an exploratory case-control study was conducted on childhood AL among children who were less than 15 years of age in Shanghai, China. A total of 131 patients with newly diagnosed AL were recruited from 3 Shanghai children hospitals. The controls selected from the same hospital were healthy children who attended the physical check-up held by the department of Children's Healthcare, or who visited the clinic of developmental pediatrics or orthopedics (excluding blood diseases and malignant tumors). 140 controls matched with cases in gender and age were included in this study. Chemical exposure were investigated by questionnaires, methylation specific polymerase chain reaction (MSP) was adopted to analyze the methylation or deletion status of 8 genes, and gene-environment interactions were analyzed by relative excess risk of interaction (RERI), attributable proportion of interaction (API) and synergy index (S).

RESULTSThere were 131 and 140 subjects in case and control group, who were aged (6.9 ± 3.8) and (6.9 ± 3.9) years old (t = 0.01, P = 0.911), respectively. After adjusting age and other potential confounding factors, chemical substances' exposure of children/mother/father were all significantly higher in cases than that in controls (Children: OR = 3.90, 95% CI: 1.69-9.02; Mother: OR = 2.71, 95% CI: 1.12-6.52; Father: OR = 1.91, 95% CI: 1.05-3.47). For the 8 genes analyzed, the methylation status of DAPK and PTEN and P73 in case group were significantly higher than that in control group (cases: 3.1% (4 cases), 16.0% (21 cases), 7.6% (10 cases); controls: 0.7% (1 case), 2.9% (4 cases), 0.7% (1 case); χ²: 7.11, 16.90, 11.38; P value: 0.029, 0.000, 0.003). The methylation status of P16 in case group was significantly lower than that in control group (cases: 3.8% (5 cases); controls: 8.6% (12 cases), χ² = 10.33, P = 0.007). The interactions of children chemical substances' exposure and 3 genes' (PTEN, P16 and P73) methylation status were probably existed after adjusted for confounding factors (PTEN: RERI = -7.01, API = -2.14, S = 0.24; P16: RERI = 4.08, API = 0.53, S = 2.59; P73: RERI = 4.32, API = 0.48, S = 2.19), we also found the potential interaction between maternal chemical substances' exposure and PTEN, P16 gene methylation status (PTEN: RERI = -1.30, API = -0.38, S = 0.65; P16: RERI = 1.70, API = 0.38, S = 1.97).

CONCLUSIONThe study suggested the strong combined effects of chemical substances exposure of children and abnormal methylation status were risk factors of childhood AL, and there existed different interaction between them, which may indicate the important role in the pathogenesis process of childhood AL.

Acute Disease ; Case-Control Studies ; Child ; Child, Preschool ; China ; DNA Methylation ; Environmental Exposure ; Female ; Gene-Environment Interaction ; Humans ; Leukemia ; epidemiology ; Maternal Exposure ; Polymerase Chain Reaction ; Risk Factors

OBJECTIVETo investigate the association between children's and their parents' lifestyles, household environmental exposures and risk of childhood acute leukemia (AL).

METHODSA 1:2 matched case-control study of childhood AL was conducted in Shanghai between April 2011 and January 2014. The study enrolled 66 cases aged < 15, diagnosed with AL and 132 controls matched by age, gender and residence. All of the controls had no hematological diseases or previous history of malignancy. Children who had been adopted and had congenital genetic syndromes such as Down's syndrome or a positive HIV test result were not eligible as either cases or controls. Information was obtained from standardized face-to-face interviews of their parents/guardians with detailed questions on demographic characteristics, lifestyle, and household environment. Conditional logistic regression models were used to analyze effecting factors of childhood AL, odds ratios (OR) and their 95% confidence intervals (CI) were calculated.

RESULTSAmong 198 cases, 66 cases were aged (5.0 ± 3.7) years old, and 132 controls were aged (6.0 ± 3.8) years old (t = 0.48, P = 0.523). The paternal drink frequencies of cases and controls were 57.6% (38/66), and 31.1% (41/132), respectively (χ² = 4.91, P = 0.027). And the frequencies of household insecticides usage in the last year in the two groups were 78.8% (52/66), and 65.2% (86/132) (χ² = 3.87, P = 0.049). Chemical exposure during childhood (OR = 4.76, 95% CI: 1.34-16.89), maternal exposure to chemicals (OR = 4.51, 95% CI: 1.65-12.33), household insecticides use during 0-3 years of child (OR = 2.90, 95% CI: 1.31-6.39), and renovating after their children's birth (OR = 3.12, 95% CI: 1.26-7.74) were associated with an increased risk of childhood AL and these differences between the cases and the controls have statistical significance. Besides, we found that frequent contaction with other children during 0-3 years old (OR = 0.32, 95% CI: 0.15-0.69) and ventilation during sleeping in summer (OR = 0.43, 95% CI: 0.18-0.98) were associated with a decreased risk of childhood AL.

CONCLUSIONOur results support the association between children's and their parents' lifestyles, household environmental exposures and childhood AL.

Acute Disease ; Case-Control Studies ; Child ; Child, Preschool ; China ; Environmental Exposure ; Female ; Humans ; Insecticides ; Leukemia ; epidemiology ; Life Style ; Logistic Models ; Maternal Exposure ; Neoplasms ; Odds Ratio ; Parents ; Risk Factors