Table 1.
Selected characteristics of the study population
| Characteristic |
HB study |
Infant leukemia studya |
|---|---|---|
| N (%) | N (%) | |
| N children with samples |
412 |
392 |
| Median DNA yield (μg) |
0.37 (0 – 139) |
0.15 (0 – 14) |
| Child’s age at DNA collection |
|
|
| 0 – 2 years |
45 (11) |
75 (19) |
| 2 – 5 years |
151 (37) |
123 (31) |
| > 5 years |
216 (52) |
194 (49) |
| Child’s sex |
|
|
| Male |
241 (58) |
183 (47) |
| Female |
171 (42) |
209 (53) |
| Case control status |
|
|
| Case |
246 (60) |
223 (57) |
| Control |
166 (40) |
169 (43) |
| Storage (Child’s sample) |
|
|
| 0 – 3 days |
108 (29) |
121 (46) |
| 3 – 7 days |
99 (26) |
64 (24) |
| 7 – 14 days |
92 (24) |
54 (21) |
| > 14 days |
79 (21) |
23 (9) |
| Season of DNA collection |
|
|
| Spring |
119 (29) |
117 (30) |
| Summer |
117 (28) |
80 (20) |
| Fall |
90 (22) |
109 (28) |
| Winter |
86 (21) |
86 (22) |
| Sample collection |
|
|
| Cytosoft brush |
175 (42) |
341 (87) |
| Epicentre brush |
202 (49) |
51 (13) |
| Mouthwash |
35 (9) |
|
| N Mothers with samples |
446 |
489 |
| Median DNA yield (μg) |
14 (0.02 – 401) |
14 (0.06 – 1209) |
| Mother’s age at DNA collection |
|
|
| < 30 years |
89 (20) |
104 (21) |
| 30 – 35 years |
117 (26) |
147 (30) |
| 35 – 40 years |
131 (29) |
134 (27) |
| > 40 years |
109 (24) |
104 (21) |
| Storage (Mother’s sample)a |
|
|
| 0 – 3 days |
110 (27) |
121 (38) |
| 3 – 7 days |
126 (31) |
104 (33) |
| 7 – 14 days |
100 (25) |
57 (18) |
| > 14 days |
68 (17) |
35 (11) |
| Maternal education |
|
|
| < High School |
31 (7) |
26 (5) |
| High School |
74 (17) |
104 (21) |
| Some college |
115 (26) |
146 (30) |
| College degree |
158 (35) |
152 (31) |
| Advanced degree |
68 (15) |
61 (13) |
| Maternal race |
|
|
| White |
349 (78) |
411 (84) |
| Black |
18 (4) |
19 (4) |
| Hispanic |
50 (11) |
30 (6) |
| Asian |
18 (4) |
16 (3) |
| Other |
11 (2) |
13 (3) |
| Income |
|
|
| < $20,000 |
65 (15) |
73 (15) |
| $20,000 -- $50,000 |
122 (28) |
183 (38) |
| $50,000 -- $75,000 |
102 (23) |
110 (23) |
| >%75,000 |
153 (35) |
122 (25) |
| Season of DNA collection |
|
|
| Spring |
128 (29) |
138 (28) |
| Summer |
126 (28) |
100 (20) |
| Fall |
98 (22) |
140 (29) |
| Winter | 94 (21) | 111 (23) |
a N’s may not sum to total due to missing data. Storage time missing for 34 children in the HB study, 130 children in infant leukemia study, 42 mothers in HB study, and 172 mothers in the infant leukemia study. Income data were missing for 4 mothers in the HB study and 1 mother in the infant leukemia study.