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Table 1 Selected characteristics of the study population

From: Predictors of mother and child DNA yields in buccal cell samples collected in pediatric cancer epidemiologic studies: a report from the Children’s Oncology group

Characteristic HB study Infant leukemia study a
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)
  1. 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.