TABLE 1.
Subject characteristics1
| All subjects (n = 394) | Cases (n = 189) | Controls (n = 205) | P | |
|---|---|---|---|---|
| Female sex, n (%) | 174 (44.2%) | 86 (45.5%) | 88 (43.1%) | 0.612 |
| Median (IQR) gestational age, wk (IQR) | 40 (2) | 40 (3) | 40 (1) | 0.043 |
| Mean (SD) birth weight, g | 3411.1 (563.2) | 3361.7 (549.7) | 3456.6 (572.9) | 0.094 |
| Race, n (%) | 0.415 | |||
| White/Caucasian | 216 (54.8%) | 96 (50.8%) | 120 (58.5%) | |
| Black/African American | 9 (2.3%) | 4 (2.1%) | 5 (2.4%) | |
| Native American | 6 (1.5%) | 4 (2.1%) | 2 (1.0%) | |
| Asian or Pacific Islander | 26 (6.6%) | 11 (5.8%) | 15 (7.3%) | |
| Mixed or others | 135 (34.3%) | 72 (38.1%) | 63 (30.7%) | |
| Ethnicity, n (%) | 0.962 | |||
| Hispanic | 175 (44.4%) | 83 (43.9%) | 92 (44.9%) | |
| Non-Hispanic | 219 (55.6%) | 106 (56.1%) | 113 (55.1%) | |
| Annual income, n (%) | 0.442 | |||
| <$15,000 | 46 (11.7%) | 24 (12.7%) | 22 (10.7%) | |
| $15,000–29,999 | 68 (17.3%) | 39 (20.6%) | 29 (14.1%) | |
| $30,000–44,999 | 45 (11.4%) | 22 (11.6%) | 25 (12.2%) | |
| $45,000–59,999 | 54 (13.7%) | 27 (14.3%) | 27 (13.2%) | |
| $60,000–74,999 | 42 (10.7%) | 18 (9.5%) | 23 (11.2%) | |
| ≥$75,000 | 137 (34.8%) | 58 (30.7%) | 79 (38.5%) | |
| Household education, n (%) | 0.212 | |||
| None or elementary school | 15 (3.8%) | 9 (4.8%) | 6 (2.9%) | |
| High school or similar | 117 (29.7%) | 57 (30.2%) | 60 (29.3%) | |
| Some college or similar | 120 (30.5%) | 49 (25.9%) | 71 (34.6%) | |
| Bachelor's degree or higher | 142 (36.0%) | 74 (39.2%) | 68 (33.2%) | |
| Median (IQR) maternal folate DFEs | ||||
| Total | 530.6 (532.1) | 536.4 (533.9) | 519.8 (516.9) | 0.853 |
| Food | 419.0 (308.3) | 439.6 (316.1) | 410.0 (299.8) | 0.833 |
| Supplemental, n subjects per category | ||||
| 0 DFEs | 280 | 134 | 146 | 0.912 |
| 194 DFEs | 27 | 12 | 15 | |
| 360 DFEs | 14 | 8 | 6 | |
| 540 DFEs | 73 | 35 | 38 |
Characteristics of the n = 394 subjects assessed in this study from the California Childhood Leukemia Study (CCLS) with genome-wide DNA-methylation data available are shown. Characteristics of the n = 189 pediatric acute lymphoblastic leukemia cases and n = 205 matched controls included in this group are presented separately. No notable differences between case and control subjects were identified by sex, birth weight, reported race and ethnicity, annual income, or highest level of household education. Maternal periconceptional folate intake was calculated as DFEs and assessed by total intake, intake from food sources, and intake from supplemental sources. Total and food DFEs were assessed on a continuous scale, whereas supplemental folic acid was assessed categorically. DFE, dietary folate equivalent.
Chi-square test,
Wilcoxon test,
Welch's t-test,
Fisher's exact test.